^^.^ > IMAGE EVALUATION TEST TARGET (MT-S) 1.0 I.I IM 12.: u Ki K ry is, as the mnft important, moft fully entered into; with a particular Account of the Siege and final OeAruftion of Jerulalem. V. Changes through different Ages in the Manners of Mankind. In which the Idolatry of the Ancients, the Teftimonies of the Primitive Chriftians and the Gothic and Feudal Manners, with the gradual Refineiuent of Europe thetefrom, are particularly defcribed. VI. VII. VIII. IX. Defcrlptions of the different Quarters of the World, , Europe, Asia, Africa, and America. Their DiviAons into Countries, Provinces, &c. their Climates, Soils, Animals, Plants, Minerals, Mountains, Rivers, Lakes, Canals, Commerce, Manufa^>itreii, Curiofities, Schools, Learning, Literati, Religious Proteffion, Language, Government, HiAory, Sec. ILLUSTRATED fVITH TEN COPPERPLATES. By J O H N WALKER, Teacher of the Classics and Mathematics, Ufliei's Iflaml, Dublin. BEING PRINCIPALLY THE JOBSTAHCK OF A COURSE OF LECTURES ADDRESSED TO HIS PUPILS* §' .y DUBLIN: ; Printed for the AvTKOR, and fold by ROBBR.T Jackson, Meath-flrect. alio, by Jambs Phillips, George- Yard, LoDibard-ftreei, LiDndon, _ and Joseph Ckvkshank, Philadelphia. ll^DCCtlZXZVIII. w: M [ ^ 1^ .-n^my-: ;/ AOrERTISEMENr. THE autlioiiiits made ufe of in the compi'ation of this work, are \\y.. Amhonj iJenczet, Samuel Boycf, William Chefvldcn, Thomas Clai kfun, David Crantz, Edward Gibbon, William Guthrie, Oliver Goldiinith, liifli Antiquities, Juilin, Ifaac Newton, Tho. Newton, Bp.Bi'noJ, Jofeph Prietllry, W. Robeitlbn, Salmon, FiancisArouet deVoUaire, Voyn(',esofOok and other circumnavigators, ChaiKs Vv(e, William Walker, The Articles of Hirtory, J. Cokely Letfom, Agriculture, &,c. in John Locke, the Encyclopxdia liri- W. F. Martyn, tannica, John Millar, Adam Fergufon, Donald Monro, James F'crgufon, and others, w'aofe names I do not now recollect, or from whom I have de- rived onl) vtry imA\ or trifling anecdotes. Uflidcs all thclc, informatioi; from Uvcral of my acqvi.untances has furniHied fomc materials, and a little iT\y own oblcrvation has I'upplied. Among fuch iiumeious authors, unanimity is not to be foun:! j and it wns hard to deteiniine on the greatell authority. Under hich embarralVmentt it <'ur,ht to be the attempt of the hiiiori m to fix on the moft probable, and in thiscaie lie may often iind a partiality in his own mind, which may be like to influence his compilation i in oppolition to fuch prejudice I have fome- times madt.' relations where I was rather Incicdulous myielf, confidering that the acccMnts of the authors whofe names ate ufed, fhould be rather plainly told than twKted or turne.l to any particular gratification of humour or wifli j foinetinits however, I have ventured to oblul's delcription a little, where accounts were marvellous beyond all probability j at otheis, 1 have given the hyptiboHcal and elegant defcription in the author's own vfords. It necefia- rily falls to the lot cf the writer of getieral geography, however painful it may be to his feelings, to tell ciuil manners ai.J giois fupeiditions ; in fuch dr- fcriptions however, I have I'eklom ^;one tho utmofl len^;th ; even on Indian feverity and on the cruel bufmefs of (lavery, all the inj^pnuity of toituie ex- ercifcd on the j)oor captives is not circumltantially entered intoj this would, if pofTiblc, have rendered the accounts n;oie difmal tlun they are. In de- fcribing of nations or focieti*s of people, vshich fomelimes forms a principal piirt ot the bufinefs of a geographer, I'uch delicacy and candour are neceflary, as indeed to require a wiiter relij^ioufly impartial: in fo important an under- trtkinj^-, however, I wifli eCpecially to be confulered only as a compiler j indeed every defci option in the whole work, except what has been imniedi- attlv dciivcd fiotn ih.c hMr, I liav. ireant as referable to the fix firlt words ci" the liouy of it, ilnr tho uai'tr may know wliat authorities i have made ufe of and judge for himillf. I hr>j.nnve reading, of a recollcwlion of what I had rtad, obferved, or heard remarked or related. When Albinus had written an hiftoiyof the Roman affair": ill '.f ! A D r E R r '■'!. •» . k ;n Grrck. and anologized for , / ^ ^' ^ ^ ^ T. •concurrence of ITZlaZ ""dertaking" j bSan jjlr"''* " becoming^ «"c,,mftances. and Xn I'"'"'''"'"' I found fvfe '""' '*'''»» ^rom 'o the calls of the dav ? w*'"'''" '"""« of fubTeteZi '";""y '"'bairafTcd -in make large ,?;in:?°"^j:i? ""^ ''''^-'•t^^^^ ^''^^"ate find themfelveJin the ve.-„ fet^'" °^ '"""'"^e and JeZ/"'''''" ""^O"*- Projluaions, but the «1 1 ' I g'^afification in the r/ '""J'' "'*'« «hev availing themfelves of rL?"'^ '°''' ^^^Y h ve not t,,?'^ '^"''"'^^ ^"^ .«'he. materials are coljjSed .^ """"'"» «»'«'' rccolleail ^PP°"""'V o^ nftant perhaps thev are «!. I ^i?'' """"rs duly puf i j " " ''''«'y. and farther adinitced%s an I "''' ""angementpli, '*".'' "''■''^overablv that thefe ft &J' **^ '''^ ''^ve flattering 1,°^'''' "|« ^^ ^y own mind the name, of ^l^'S/c^mnr""^''*- " P-' of ' 'hei ^r^r^ °" '''^^' '"^o^'ct «"»y is knoin. ConvL<.,t "P',"'"S them, and forJI° '''■"l? '''=" «ouId of bowine to or fla?. • "•* *» ' a"' in my hea« .ru""" '"''"d the tific »>elieve a happv afr, ""^ " '"'"ow-worm/it is eL? V ' ''J'' ='"'* '"dccencv -ong in t'^J SrrnU' »- -moved KI^ ^^..^y^'J^/o- b.^I and in fpeakine of I " ^y ^^^" t'fJcs rather tiiu'^.'^ '^^ '' ^o^'d be "f^ of thS iideit 'r ;, Z ^'-^rs 'o them?Y Sd ^fl'^T'- "«-« ^ g've ir as a r>J, If ,t " "'^y tend to ufeful LL ■ *''^' only to n,akt complimentary'"; t^.:,nr*r '^ "^ ^"^ «« oHrr'tv?';''- -" '« a"g"age, but^s the f ft ■' ^°l^'' '' ^ould be un 'e ftlnV '' ^''"^ '^^'^A'.' J. had written, " the S.>" J. •' ''^''' »''» ^orS s flV*"' '\'"^ «-" *"^ of the people T). "'e^n'ng «he Sir of tJ.^ ii ''fV '" 'his work 'orinftance in ,h/ '"•^.''''o have agreed tn . f ?'"'^ " ^^ce or the *5ir Hans S]o"n •• «'r^"'>^ '^ere occuVed •' the i" "?.??'" ^V '^at ,i j/ P-effions amTreWs L'lV'J:;"'^" Alexander -fth''' ^'^'"^^'" "!"«; Altering titles ; the e are rh. ^'■' ^"■' ^o-d, 4. ^hjJh "' *'* "'^er ex- accounted genteel »Lr ' "^"'^ of trade, o7ftpt; • PP''"'' 'o »"« aa "-hen embodi d with ttT'*""" ^^'«" ^^e moVwldH '" H*' ^'"^'' are ., Days, Month^'Jj ''„!,^^"^"'<^ to ^void the ment,^"n'^of h?' ^'^ ^PP'^'Jation 'Jolatryj andinVr •.• ' ^'^' ''^ve received «;.. P''°P«- "ame . '^»'"'n,\'hrj„pi; f"t'h;'"L'''^ '■°'ar fyrterj hav.::: "n^'^'v°^'g'"ated .•„ r. • */ I I', €^ i^. Ai'-i i ^ir CONTENTS. ROOK I. PRINCIPLES OF PHILOSOPHY and SKETCHES OF GENERAL HISTORY. PART I. The Figure of the Earth, and the Principles of Mechanics and Aftronomy. \ - ' 1^ • '■.'^^ ., ■ V'^ SECT. I. Figure of the Earth, Antipodes, Altraflion. Sphere. Expe- linient. Antipodes. Univerfal Law. Effefls. Page i, 2, 3. §. II. Diviftons of the Earth, Hijlory of Geography, Scientific. Political. Natural. General. Geographic Information, p. ^ to 5. §. III. Univerfe, Centripetal atiJ Centrifugal Forces. Planetary Revo- lutions. Starry Heavens. Forces combined. Applied to Sun and Earth §. IV. Mechanics. Powers. Law. Inclined Plane Pulley. Lever. Wheel and Axis. Balance. §. V. Day, Night and Seafons. Diurnal Revolution. Changing Day. Sealons. Polar Day ocrew. p. 7. Heat diverfe. Wedge. h Definitions of Circles, ^c. Celeftial and Terrejlrial. Equinodlial. Tropics. Polar Circles. p. 9. Great Zones. § VI and lefs Circles Celeftial Circles. Ecliptic. Zodiac. Meridians. Terreftrial Lat. and Long. Afcenfion and Declination. Points and Colures. Celef- tial Long, and Lat. Finding the Latitude. Finding the Longitude. Maps. Climates. Poles of the Horizon. Horizon. Azimuths, Cardinal Points. Altitude, Almicanter. Pofitioiis of the Sphere. P . ! I . VII. Moon, Tides, ohlate Figure of the Earth. Phafes. Eclipfes. Experiment. Moonfhine. Lunar Day. Telefcopic Obfervations. Tides. Their Caufes. Earth a Spheroid. Other EfFtdls of its diurnal Revolutions. p. 1^. §. VIII. Planetary Laws and the Methods of ini>e 'Kigali ng the Motion, Magnitude and Dijlances of the Planets. Mo.ion of the Sun. Planetary Laws. Deception ot the Senles. Corrtcled by reafoning. Afcertainment of the Diftance and Migniiude of Objefts. p. 2 1 . IX. Solar Syflem. The Sun. The Mercury. TIi^ Venus. Our Earth. The Mars. The Jupiter. The Saiurn. The Georgium Sidus, or Georgian Planet. Number and Order of Comets. Threat- ening Appearance. Ufe of the Comets. p, 24. X Afironomical ConjeQures, Dijiance and Number of the Stars. Conjeftures. Fa^. Dillance of the Stars. Number of the Stars. Starry Heavens. p. 27* _^ . A PART § § % t. *. ! • H ■ ( — ■I i -.* > » * . C O N T E N T S. TheOeconomyofLL'* *^ "■ / <" the fublumry Works nf r • SECT. I ,„,, '"""8 »"'' i-inimate. ^'""'"'' f^-'h none or M° gn,"'""^;^ '^?«""''^ '"d Effflric S ""^ ^""«'on. General Preff„;^- „f ^f^'^'r- Non-CondX," '"f^<- . ^"»''- Sound. Improvement, n'^"?' ^'^^^'^' C cila^l"'''^^^""''^- Barometer Tm? r .^'^"^on of the Arm.r u '°" °^ ^'otes. ^ rh/oJor^nS^r^^^^ v- fe ^^e'^^ ^ Air. Meteors. ^''' °^ *^e Atmofphere AnVf% ^*"^- «-V. HydroPatUks R' ^ ^"a'/fis of the ^ ^omparifon of R,,,,,. • l . ^'"' Nerves, '/les, ublervations. S^r n ^j ^' Defin.nons Oblervation.. P A K iir. J-b„.„c, b„,h Man :'d B^Sr^""^ ""'' ^-""^ "^ tt' 1 ! jECT. 7 n„ /• '^^anfportatonofr'''-y'"^^^"- Longe^^v T ^'"^^^' ^ "• W J?"/^ S°"^'«J' to Botany Bay.^ "^- ^^^^'^ ^'clers '- ^«-^s. P;oduS/rn^, Mount^a/n -^ «^t Ice. m p. 87. Soutlj M -f. > both Ruins. CONTENTS. h. III. AhftraB of CaoKt Voyagt, North Paflage to India. New Holland. New Zealand. Friendly and Society Ifles. Sandwich Iflands. Weftern Shore of America. Vicinity of Afia and America. Owhyhee and Death of James Cook. Kamtfchatka, the Return. Obfervations. p. 99. S. IV. jifia. Tartary. Southern Nations. Arabs. p. io3. \ V. jifrica. Egypt, Barbary. Ethiopia. Negroland and Guinea. Enflavement of the Africans. Slavery in Antiquity. p. no. §. VI. jtmirica. Complexion, Features, &c. Intercourle with Europeans. Pafllon for Liberty. Public Aflemblies. Mode of War, Cruelty. Unreferved Frisndftiip, Funerals, &c. p. 122. S, VII. Lands round the North Pole. Supcrftitions of the Green- landers. Their Strength and Agility. Houfes, Tents, and Fealls. Manners diverfe. Tartars, Laplanders. p. 126. §. VIII. Europe. Arts and Sciences. Manners. Remarks and Re- fledtions. p. 134. §. IX. Different Appearances of the Earth. Polar Regions, Tropical Climates. General Obfervations on the People. P* '37* §. X. Diverfity of Animals. Whale Fifhery. Polar Regions. Mi- grations of Birds. Migrations of Fifties, Tropical Seas. Africa. Europe. Afia, Iflands of the Pacific. America. P* "44' S, XI. Manners of Animals. Care of their Young. Animofities, AlTociations. Influenced by the Human Race. Prowefs of Man. p. 154. PART IV. SttccefTion of Empires. SECT. I. Moft remote Antiquity, Jeivi/h Nation, &fr. Antediluvian World, Flood. Origin of different Nations and Tongues. Remarks. Chinefe, Japanefe. Arabians. Ifraelites. Separation of the Ten Tribes. Captivity of Judah, Return, &c. Coming of our Saviour. Roman War and Siege of Jerufalem. p. 1 64. §. II. Ancient Hi/iory. Scythians, Egyptians. AlTyrians, Babylonians, Medes, Perfians and Macedonians. Romans, Goths, Vandals, &c. Mahomet. Conftaniine, Bifliop of Rome, Charlemagne. Grecians, Carthaginians, Gauls. p. 173. ■5. III. Modern Hiftoiy, Mahometans, Chriftians, Crufades. Tartars, Turks. Modern Europeans. PrefentDivifion of the Earth, p. 176. \ PART V. Changes through different Ages in the Manners of Mankind. SECT. I. Ancient Times. Patriarchal Manners. Origin of Arts and Letters. Aftronomy, Geometry. Idolatry. Perfecution. Primitive Chriftians. Commerce, general Reniaiks. Architcfture, Learning. Germans in their native Wilds. p. 182. *. II. Middle and Modern Time:-. Revolutions, Feudal Syflem. Crufades. Refinement of Manners. Laws. Knight Errantry, Chivalry, Heraldry. Revival of Literature, Difcoverie^, Commerce. Religious Profefiion, Remarks. p. 206. As ,. BOOK i\ CONTENTS. BOOK II. H If DESCRIPTION OF THE EARTH, UNDER ITS POLITICAL DIVISIONS. With ihe Situation and Extent of the feveral Countiies in each Quarter of the World, their Chief Towns, Climates, Produce, Commf.rce, Manufactures, Curiosities, Schools, Governments, and an Epitome ot their Histories. PART VI. Defcription of Europe. KINGDOMS of Europe P. (2 firitiih Ifles - - (3 England and Wales (12 Scotland - - (26 Ireland - - (34 Denmark: and Norway (47 Sweden - - (J4 Mufcovy or Ruflia - (57 Poland - - (60 Pruffia - - (63 ) Germany, Bohemia, I- lungary (65) ) Switzerland - (73) ) Holland - (76) ) Flanders - (78) ) France - (80) ) Spain - (85) ) Portugal - (9') ) Italy - (93) ) Turkey in Europe - (98) F. i V 7\ PART vir. Turkey in Afia - (105) Tartary - - (106) China - - (108) India . - (114) Perfia - - (•'9) Arabia - - (>23) Defcription of Asia. (105) Kurile Iflands, Japan, Formofa, Ladrones, Philippine Iflands, Spice Iflands, Celebes, Sunda Iflcjs, Nicobar Ifles, Ceylon, Maldivia Iflands, South Sea Iflands - (1*5) PART VIII. Egypt Barbary Defcription of Africa. (133) Weftern Parts of Africa (137) Eaftern Parts («39) (142) PART IX. Defcription of America. NorthAmericanlflands(i46)(i47) Portuguefe America (161) Britifli America - ('S^^) French and Dutch America, American States - (1S4} Guiana - (162) Spanifii Territories in North Spanifti South America (163) America j^r - ('54) Amazonia,- Patagonia (i6«;) Indian Nations South America (i 59) Iflands of South America ( i6b) ('59) •m ::^y ■f^,. E R H A T A. ITS (73) (76) (78) (80) (85) (90 (93) (98; Pa|. LIo. 6 10 10 40 4« 44 54 70 84 «S 94 laz 131 >35 '45 '53 160 165 167 176 180 186 187 SIX of the I'.ote, for vary rtad will vary. 1 1 for as the utmoft thicknefs ii to thr length, r. ai the length is to the utmoft thicknefs. 6 of Note, far autumnal, r. vernal, laft a lines, for cone, r. roff .' *" A 3 ' \ work was written rh ^^*^°»^''"'i of thj Afr' n^' ^^on, different quarter rn/^ ^'"'°"^ ^o tLfend *^^ «" abolition antl indeed ftJJI ! ^° '''^ Legiflature on!? ^ '*'^^e pouring i„ wko can wiH./fn/j f ^' 'hfir eaft t„,r]!. r ' '" "'•n of afflu «"<'" P-donEgo^ft, "f- '° ^«« »" own feeE," A""-"'"/ W: nie fome ftriftur^r **'"Ss m a Great klr uV^ The Bri„7I, Parl«,„" „,.'.'■' '^'"'- ''''mrokiUon of »>/wl.icl,fe™,7,;' ='«'"gw;» cCmhy genera /y fbr ?„«• ^"'.oe. when the UrS ^ ^"" ^'^es. and proJonjr rather k , "^^a-'ure which .-m- "°^ '" Agitation •It", and o thi:l^'«'""'"'"^ftrw lri?,^"'^/'">«<'" -he eternal «.or„„,g. / °'^■^■••'=<^=y til >.-, f- ■M f-^y^ ^- If-V tr «alfa vear •'» . u- l • "" 'Pa rks one dav nn^ /i. . ^ "'^" eJeC' r^ difcoSntd hrLf'f" ""'"2 ''" '^0 .le "otr.'' f /"I >>» hand f" fix weeks (?,„ ly/""'' """'hs- After wS*^; '■'" "Pw^ion 'Jot fprinffs in Ir*.i«„ J .i ® ancient wnter R«^^ ^ waters were loft ; however wA'^'^'^'^^^^^^'-ewTrer^^^^^^ ^'^^^^ ^^e ■ kreacer degree of '^rfei'' '".'' '"'>■ >>- dr!Z."7!T "^"P?'^ "■' a coiiip/ete/if vas firft eJec' '^^ next, for and her Jiancj the operation 'ng repeated operations, way by one ch the a/- two bits of ent courfe. Its tiirough A:Ies occa- *^** That mediate// )r the par- 'edtrifying >ofc of no trician to 'an might ?rs were here are *ng fince »^e note, ?ht into \ by its Matlock' iftcJ. Airthei- ^ fybeate them " f >i7 tije 4' 1 in a ,.? [late it ^ 'beate * Dublin 5tret- 'Ucan :for- lifce- )ns. IJa? cian arly ions ^ith Ich \ I » 'II Mfli™ ■.4s.- ir \ ■-< :^-^«iffww ^ tf M>^^ ^^ .».ji**J»vWMHfci /i II ' i y.r SJ- i-: ' -.' •J; 4- •^■m I • k .;'ia ^ Tl '^ -^ T ELEMENTS u O F .-. / GEOGRAPHY', PHTT OSOPHiC AND HISTORIC. "W PARTI. THE FIGURE OF THE EARTH; AND T H X ELEMENTS OF MECHANICS AND ASTRONOMY. FROM the authorities premifei'., it appears— In the remote age* of antiquity, ere man had mad ; any great progrefs in fcience ; in the yet uninformed nations of the world ; among thofe people, in im- proved nations, who think on the nature of things but feldom, and then very fuperficially ; and among the puerile reflexions of the great- eft geniufes ; vague and romantic have been the conjeflures, reipc6l- ing the form, extent, and boundaries of this earth. From our narrow, circumfcribed view of things, we are naturally induced to fuppofe it neceflary for every heavy body to have fome- thing to reft upon, or be fufpended from ; hence, fome have imagin- ed, the ftars to be lamps, let down from heaven by golden chams; the (ky, a vaft arc'i ; the earth, an extended plane, refting on they knew not what, and bounded they knew not how. 7" >y^g,>. ■ ' M SECTION I. •al.lE.-*^-?^;* • '.;' ■ Figure of thtEAKTH f Antijodes, Attractiow; J. Sphere.] It clearly appears, however, from the r^^ptj&^iet men of fcience, that the land and water of our worl^' tote^ery form a large round body, which is balanced in the ether, Twe cbje moon and planets j a globe of fo prodigious a fizC) that its nigheft B mountains. U i \l E L E»M E N T S OF P. 1. ' Jvi^' mountains, are compared to iit'elf, but as a grain of dud on an arti- ficial fphere ; and, to us little mortals who dwell on its furface, its Iplierical figure is hardly dirceriiible; yet we, without failing round the world, as fome have really done, as the navigators Drake, Anfon, Cook, &c. have fuffi:ient room to conclude, wiih but a little obfer- vution, that the earth is a globe, or of foine fiiuilai fliape. 2. Experiment] Flnte I. Let us take a (land on the lea fliore, on a clear day, and view (liips leaving the c oaft, in any direftion whatfoever ; as they recede from us, we may diftindlly obferve thv,* rigging of the velTels, when the hulls are quite out of fi^hr, as if funk in the waters. In like manner, in an evening, from the top of a hill, the obferver may diftindtly fee the fetting fun, when it appears to thofe below, to have funk below the Horizon, Nay, a perfon of fwift foot, wh^n it has fei to him below, may. by running up the hill, regain his view. Thus, when lifing, does he firft tip the tops of the mountains with his rays ; and thus do failois, on their fiift making land, difcover the high parts of the coall, but not the very lliore, till they are pretty clofe in with the land. Now, were t!i<* furface of the fea an extenfive plane of waters, through defedi of fight only, thicknets of atmofphere, or fome fuch like caufes, we would lole fight of the objedls, and then they would dilappear all at once. .oa the Surface of the earth, they w.ll p. 1. S. tl. ASTRONOMY. 5. KffeHi.'] This principle ol attra^ton, feems to be as a chain in \\\ie works of ihecreaiidn, to bind rhe elements Under harmonious or- der, and wholefome lawi ; for owing to this principle it appears, that tlje world remains a folid ball ; the Tea keeps in the deeps of the earth ^ the tiiountaiiis refl firni on their foundations, and things univerfaily hold their refpeflive places *. By the fame principle of attraflion, will the rivulets of water tumble frniji the hills, glide down the vallies, and fettle in the deep. The »ir is fomething, for we cannot live wit'iout breathing it; and when in motion, under the name of winds, it impels fliips through the wa- ter with incredible force. It is found to be an elaflic fluid. It will alfo gravitate towards the earth, becoming heavier the lower it dc- fcends; and, if there be any light things in the way, fuch as fmoke, mill, &c. whether at large, or confined in balloons ; any things lighter than itfelf ; thefe will naturally afcend through the air's fupe- rior gravity, to rCj^jons of equal rarity with theujlelves; as the den^(j water bears up light things from finking, while heavy bodies force their v/ay to the bottom, in fpite of all the redllance the water can niake. liking S E C T I O N lt» Di'ViJtohs of the EaRth, Hijlory of Geographv. 1. Dii'ifont.] The moft obvious divifions that prefent themlelvM, on a view of the furface of our globe, are thofe that arc mkde by the yielding water on the crooked fhore { thefe are outlines in feme mea- fure fixed and permanent. 2. Scientific.] Men of fcience have laid out the earth in degrees of longitude and latitude, and divided it into zones and climates. 3. Political.] Befides thefe, there are other divifions of a more fluc- tuating kind ; thefe are the political boundaiies that feparate kingdoms and empires, which however we njay difregard, as delineated on the geographical chart ; they have generally been marked out by the (word of the conqueror, at the expence of the blood and carnage of his fellows. B z Kingdoms, y A'- Teas. equiponderate; but if one of thefe ropes, inftead of being rolled up in a bundle, bq.^ loofened out, and let to hang at length, down the mouth of a deep coal pit or minjp,;^ the rope, thus extended, lofei fome of its weight, though it hang perfe£tly free as , before, from the end of the balance; and the rope that remains above, preponde* ': rates, through the other's being attra£led by the tides of the coal pit, in direftiont' ' counteraAing its perpendicular defcent. * Plate I. Lei A reprefent the round world ; the particles of matter compofiag it, being brought into order, will naturally, by their mutual attraftion, adhere to . each other, and thus be prevented from falling into confufion. Lee us ima^ute a . heavy body, B. without it, by attraction, they will be drawn towards each ddttr,"^ till they toach. B. may be faid to fall or gravitate its motion alone, being otitlrVi'''' able; the world fcarcely moving, on account of its magnitude; as a large veflet j»<|l. the water fcarcely ftirs, when the light ftllT is drawn to it, or pu/hsd from it, by » pole, though they are both a£led upon with equal force. Indeed the quantity of motion is equarih both, though the fwiftnefs is very different; for quantity of. tmuibft in a moving body, is according to the force applied in moving it ; but fwift^ ^^h .*ccoi ding to the diftance moved in a gi vt n time, /•'^ v:!.>j: K-, '■0^: ■i <■ A t .-v¥^-.. s«(e=;- ELEMENTS OF P.I. Kingdoms, provinces, towns, &c. are divifions of the earth, that change with the atfairs of the nations that have made them j and ac- cordingly, in different ages, thev vary their appearances. 4. Natur/il] The natural divifioRs of lanvl and water are more fixed. PI. I. . Definitions or Land. 1. A continent is the largeft continued traft of land, conipre- hending feveral countries in it- lelf. 2. Capes or head-lands and promontories, fhoot out into the fea. 3. Iflands are entirely fur- rounded by water. 4.. A peninfula, alnioft an ifland, is .furrounded on all fides by the water, except where 5. An ifthtnus, or narrow neck of land, joins it to the main land. Definitions or Water. I . An ocean is the grcatetl ex- tent of water. s. Seas are particular or con- fined parts of it. 3. A lake is a body of water enclofed by the land. 4. A gulph is furrounded by the land on all fides but the en- trance. 5. A ftrait is a narrow pafTage between two feas. 5. General.] Geographers have ufrally divided the world into four quarters; Europe, Afia, Africa, and America, If we take Europe, by much the fmalieft divifion, as a place of departure, America lies to the weft, Afia to the eaft, and Africa, to the fouth. America is call- ed the new world by Europeans, from their having but lately difco- vered it ; the other quarters, they call the old world. America is feparated from the old world, on the weft by the Atlantic Ocean, on the eaft by the Pacific. 6. Geogrophu Information.] Our knowledge of the different parts of the earth, we have derived from the accumulated obfervations and difcoveries of diftant ages and different countries. We may reckon Mofes and Homer, among the geographers of the moft early times; but the places and the people mentioned in their writings, are gene- rally now no more. The conqueror Alexander employed engineers in his fervice, whofe bufinefs coniifted in meafuring and keeping an accurate account of his marches. Thefe were extended into India, the borders of Scythia, through Judea and Egypt. By reducing Tyre and Sidon, the Greeks informed themfelves of the places to which the Phenicians traded by fea. Ptolemy Evergetes led his armies into AbylTmia, and thereby obtained a knowlege of that diftant country. The conquefts of the Romans added both extent and correftnefs to the geography of the ancients. The great roads of their extenfive em- pire, meafured through their whole extent, proved extremely ufeful ; and the Itineraries afforded confidbrible afllfEance. Accordingly, the geographers of thofe times, were enabled to defcribe countries before hardly known, and correft the errors of former writers. Their know- ledge of the earth's furface, however, was but little, if compared with the difcoveries of the later Europeans. In the fifteenth century, the Portuguefc lHB55®rrs:^^'=-"-- s. in. ASTRONOMY. Portu^uefe opened the way to the Pacific by the Cape of Good Hope. The Spaniards afterwards attempted the paiTage to India, on the well, under Chriftopher Coluinkus ; but inflead of India, they difcovered America. It might fecni fuptrfluous here, to enter into a detail of what followed : how the other European powers embatked on fmiilar ^nterpiises; how they ha v« penetrated into every habitable climate on the earth ; and how often they have abufed their fuperiority among artlefs and feeble nations. In fhort, ftom the travels of miinonaries, and adventurers, and from the voyages of navigators, we have now iia acquaintance with every quarter of the globe. SECTION III. Universe, Ctntripetal and Centrifugal ToKCt^, The principle of attra^ion, by which the order of fublunary things is kept up, naturalifts fuppofe, upholds not only the component paita of the earth, but the globe itfelf and the whole univerfe. 1. Planetary Rn/olutiuns.] They tell us that the earth is a pjanet ; that it and (ix other primary ones, move round the fun, in oibits, nearly circular ; that fome of them have fccondary planets, fatellites, or moons, accompanying and moving round Uiem in their orbits, as our earth has one moon ; that the comets alfo move round the fun ; that all thefe together compleat our folar fyftcm. From the motion of the earth on its axis, and from its orbit round the fun, they derive all the changes of night and day, and the vicifll- tudes of the feafons that we experience; and as the other planets are fubje£t to the fame phyiical laws as our earth, they by analogy con<> elude, that they have their feafons, their days, and their nights, as well as ours; as alfo inhabitants fuited to their refpeflive regions 2. Starry Heavens.] 'TIS conjeftured, that the fixed ftars are all of them funs, round which planets may revolve ; though from their im- menfe diftance from us, we cannot difcover them. The focial idea prevails, that tbele may be the manfions of beings fuited to their places ; to whom the Great Patent difpenfes marks of his goodnefs as welt as to us. And indeed, from the immenfe diftance that the fixed ftars are from us and our fyftem, it may not be inconfift ent with the truth to believe, that thofe huge vivid globes, loft to ou view in a point, were created to fupport and cheer other creatures, ra- ther than merely to guide us in our little peregrinations on the globe, or aftlft us in our aftronomical obfervations. 3. Forces combined.] Aftrononvers fuppofe, that a mutual attrafllon exifts between the fun and fixed ftais, or funs, by which they are all poifed in equilibrio. They imagine, that the funs are a fort of centres of gravitation to the planets that furround them; that the attraction or centripetal force, which would alone draw them to the centre, is nicely combined with an impulfe thefe bodies have received, which of itfeif, and unreftrained, would caufe them to flv off in a right line through the immenfity of fpace. This impulfe is called the centrifu- gal force i that by the combination of the centripetal and centrifugal forces, ij.^< ELEMENTS OP r. I. l\ forces, the pinnets are naturally carried in orbitj round the fun j that the primary planets are as ctiitres of gravitation tu their rutellites or moons; and they account tur the revolution of thefc, from the fame phyllcal laws ♦. 4. Jp^/ieJ to Sun and Earth] From the unexpiicable law of gravi- tation or attraction, that univcrfally prevails in the natural world, it inay readily appear, that if the fun and the earth were the only bodies in the univerfc, and they at reft at a didance from each other, by their ntutual attraction they would directly be drawn towards each other. The fun being a million tiiucs bigger than the earth, the latter (as a light flviti'drawn toa large veiTch would move with great velocity, and fall to the fun ; the fun would flowly meet the coming of the earth. As each would thus be influenced by the other, fo the Ci^ntrifugal fjjrce which, combined with attiadion, carries the earth round in its orbit, and pievents it from fulling into the fun : it alfo carries the luminary round in an orbit, and prevents it from falling to the earth ; and the centre of their revolution or their centre of gravity, lies between the two bodies. As the earth is but very fmall, in comparifon vith the Can, it is whirled round in an orbit, proportionably larger than that of the !• ^ It ii abferveJ in the natural world, that matter U of itfelf pailive, indilFerent •I tom'tiofl or reft; that hence, were a body put in motion, it would continue to piove on in a lighr line, without end; or it' it wai at red, it would for ever renuiii (0, unlefi the>e was foaie active caufc to produce a chantse. PI. n.fig. J, Let A be a body uninfluenced by the attraction of any other body; let ut fupp' Tu t^ai It receives an impulfc that would carry it in a certain time to B. if at the |4me time it receives a contrary force of equal ftrengtli, that would alone I.t th« f^me tin>e >arry it to C, the contrary impull'es will neutralize each other, and the body remain at A. bt^t if with the original impulfe that would l.ave carried it from A. (o B. it not interrupted, it receive at the fame time a fotce that would of itfelf rarry it from A. to D. the body wi|l move in or defcribe the diagonal AE. from the combinations of the two forces AB. and AD. and will at the end of the certain time, be exa£tly at the fame diftance, as when it firft fet out trom the places II. and D. where the acting forces refpe^tively tended tu carry it, if the forces are equal ; but if the impulfes AB. and AD. be unequal, fig. z. the body will be found at the fame diilancc from the more remote place of tendency B. as it was from the nearer D. and reciprocally at the faiae dift^nce from the nearer place of tenden> cv D. as it was from the more remote one B. on its fiift fetting out from A. When the forers are equai^ thediagonal AE. or motion produced by the combination ef the two impulfes, according to the directions of the force applied, vary through every decree of fwiftnefs, from abfolue tcR, to the dggregnte of both velocities, add- ed together, or produced in one ri^ht line. When the impulfes are unequal, the fwiftnefs of the body will vary, according to the direction of the forces, (rom the fam of the two velocities added together, to that of the greater, when the lefs is fub- ttaded from it. Fig. 3. From thefe known principles of n^atter put in motion, it is difcovered how and why the planets move in orbits round the fuQ. Let S. reprefent the fun j f.S. the attradtive force v.ijereby the earth is drawn towards the funl £F. the centrifugal impulfe: by the combination of thefe twe forces acting at the fame time upon the earth (or it may as fitly be faid, between the confliA of the two) it would naturally move along the line EE« in the fame time it would have moved along either of the other lines fingly j but, as the centrifugal and attraAive JFarces afl not by fiarts, but uniformly and conftjotly, the earth inftead of being faonci along in right lines, is naturally refolved into a curved one, or or- |>it. EOE. It^may here be remarked, howerer, that the fun is not ftriftly a centre of gravi. ^fion to the planets, nor are the primary planets, that have moons or fatelUtef ac* {:finpaoyiog thenii firiftly centres to the oibi that revolve round them. iSue^ m" S. iV. ASTRONOMY. the luminaiy, and their common centre of gravity lies confequently very near the centre of the fun. The fame laws hold between the fun and other planets* and between the primary planets, and their fa- tellites, or moons. SECTION IV. Mechanics. On thefc principles, which fupport the order of the fphcres, ihe fcicnce nt niechaiiics wholly depends ; and in a very flight view of the mechanical powers, there teems a fatniliar leprefentation of the natu- ral laws ot the univerfe. 1. Puwert.] The mechanical powers have been reckoned fix ; the lever or balance, the wheel and axis, the pulley, the wedge, the fcrew, and the inclined plane : The three latter may be confidered as different modifications ot the principles of the inclined plane ; the three former, the fame of the balance or lever. 2. Laiv] It is a law in mechanics, that whatever be the force of the power applied, it can produce no more than a certain efFcd. This eife^, theiefoie, is only differently modified by all the various contri<> vances of machinery. By fome machines velocity is acquired ; but what is gained in fwiftnefs or time, is \oA in power. By others an in- creafe ot force or ftrength is gained ; but what is acquired in power, is luft in velocity or time. So the eff^ft remains ever only equal to the force applied, whether the weight of a (lieatii of water, as in mills; the expanfion of afteam, as in fire-ongtnes ; whether the llrength of t horle, the force of a man's arm, or any other thing. If therefore we confider two weights, as the contrary forces applied to any of th© mechanical powers or machines, in whatever proportion the g« ?ater exceeds the lels ; if in the fame proportion, the rife or fall of the lefs, exceeds the afccnt or defceni of the greater, when the int^rument is put in motion, the weights, however different their magnitudes may be, will themlelves naturally equiponderate, if the machine be let to reft. Thus in the inftruments or machines Fig. 4, 5, 6, 7, b, &c. vrhen put in motion, if the weight G. be to the weight or power of the hand, applied at (^ as the afcent, def^ent, or motion of C^ is to the rile or fall of G the weight or forces G. and Q^ fhall, if lett to ihem* felves, naturally balance each other. All the mechanick powers are fubjeft in fome meafure or other, to impediments from friction ; but fetting this adde, aad confidering the nature of thefe inftruments only in theory. 3. Inclined Plane. "^ The inclined plane affords a means of railing a weight with lefs force, than what is equal to the weight itfelf. Sup- pofe it was required to raife the globe G. Fig. 16, from the ground H. P. up to the point whofe perpendicular height from the grourid is' H. I. If the globe G. was drawn by a cord parallel to the plane I. P.- .- let the cord be continued on and pafTed over the pulley ; and let the*^ weight Q;_be hung to ir, or a hand may be applied to it. Now if th» weight nr pawtr of thi hand nf (^ bears the fame proportion to the / % ELEMENTS OF P. T, A • - 1 u fl globe Q, as I P bears to I H, i.e. as the fall of Q^bears to the dl- reft afcent of G from the ground, the fmaller weight or force of the hand at Q^will fupporl the globe G. 4. M'^e(/ge.] The wedge may be confiJered as two inclined planes, joined together obliquely, for gaining of power. When a wedge is put under any weight to raife it up Fig. 17. the force with which the wedge will lift the weight, when driven under it by a blow on the end C A B, will bear the fame proportion to the force wherewiih the b'ow would aft upon the weight if dired^Iy applied to it, as the ve- locity which the wedge receives from the blow, bears to the velocity wherewiih the weight is lifted by the wedge ; i i e i fto the utmoft th iek - j Mifj GAD 1^ 16 ItlL Ilh^lIi i ?f fhr wi id g 8 ; and the fame proportion holds in cleaving of timber, or producing any iiniilar efFeft. 5. Screw.] The fcrew may be confidered as an inclined plane, twilled round a 1 oiler j fomeiimes it is double, treble, or fourfold ; or it has two, three, or four threads, or twifted inclined planes. There are two ways of applying this inftrument. Sometimes Fig. 18. it is fcrewed through a hole or box, fitted to the fcrew or pin. Some- times Fig. 19. it is applied to the teeth of a wheel fitted to receive it. In both thefe cafes, if a bar QJ^ be fixed acrofs the fcrew, the fore© wherewiih the end G of the Icrew Fig. 18. prelles, and the force wherewith G the teeth of the wheel Fig. 19. are prefTed, each force bears the fame proportion to the power Q^applied to the end of the har, as the velocity of the end of the fcrew, or of the teeth of the wheel bears to the velocity of the power (^when the fcrews are turned. 6. Pulley.] It is ealy to eftimate the effeft of the pulley, fimple or combined. In Fig. 9, where the weight hangs from one ftring, the power E, fufpends a weight equal to iitelf. In Fig. 10. where the weight hangs from two, the power Q^holds a weight double of itfelf. In Fig. 12. where the weight hangs from fiye, the power Q^ balances five times its own weight. In Fig. n- where fi:^ ftrings fupport the weight, the power Q^fufpends fix times itfelf. There are tv/o other ways of fupporting a weight by pulleys; one of thefe is reprefented in Fig. 13. heie the weight being connefted to the pulley 13, a power equal to half the weight would fupport the pulley C, if applied immediately to it. A power only equal to half of that which fupports C would fupport D, but half of this laft pow- er applied as at Q^ fufpends D, and confequently the weight G ; the power therefore at Opioids eight times itfelf, applied at G. Another way of applying pulleys to a weight, is reprefented in Fig. 14. To explain the effeft of pulleys thus applied, it will be proper joconfider different weights hanging as in Fig. 1 5. Here if the power and weights balance each other, the power Q^is equal to the weight ; B C is equal to both together ; and D is equal to the power Q^ and the other two weights. All the three weights together, then, are equal to feven times the power Q; But if thefe three weights were joined in one, they would produce the cafe of Fig. 14. fo that in that figure the weight G, where there are three pulleys, is feven times the Po\yer Q^ If there had been but two pulleys, it would have beei^ thr^e times ; and if four pulleys, fifteen tiiues the power. 7. Lever 1 ^' a*,- - if'; p. T, S. V. ASTRONOMY. one led to tiie half pow- , the f>"g- iroper lower 7. Lever.] The lever is generally underftood to be a bar made ufc of tor moving great weights, or effedling foiiie great force. Fig. 5, 6. The bar is applied in one part to fome ftrong fupport ; this is called the fulcrum, and is ihe centre of iis motion ; the tariher the power Q^is applied from this centre, the greater mutl: be its mo- tion, but the greater weight will it raife at G ; on the contrary, if we fuppofe G to be the power, and Q^the effeft or the weight to be raifed, the nearer ihe fulcrum the force is applied, the Jefs will be its power, but the greater velocity will it give to Q^ We may condder our own linibs as levers of this latter defcription. a. PI heel and Axis.'] A lever maybe hung upon an axis Fig. 7. and then the two arms of the lever need not be continuous, but fixed to different parts of ^ .e axis, and the axis here muft be confidered as the fulcrum. From this cafe of the lever hung \ipon an axis, it is eafy to make a tranfuion to the wheel and axis. Fig. 8. Here the axes may be con~ fidered as fulcrums, and the wheels and rollers as levers, whole lergrhs are their fcmidiamelers. By different combinations of the wheel and axis, n>any of the moft complicated machines are princi- pally made out ; and the way of .onmiunicating motion from one wheel to another, is by means ot teeth at the extremities of the wheels, or by cords or bands, as in the combinauons of pulleys. Ir has already been remarked, that no combinations of the mecha- nical powers, however nice or complicate, can encreafe the whole ef- feft of the force applied ; the force can only be modified into certain degrees of ftrengtt. or velocity. 9. Balance] While we may read the laws that govern the fpheres, in the properties of any of thele inltruments, whether fimple or com- plicated, they appear the moft obvious in the fimple lever, balance or fletlyard. If the two balls G and Q^were connefted together by an inflexible rod, ftcelyard, or lever, drawn from centre to centre, and the rod was fo divided in C that the pai t C G bears the fame pro- jjoriion to C Q^as the ball Q^bears to the ball G, then the rod being fupported at C, luppofe by a thread, will uphold the ball. Now if the thread be twifted, fo as to nmke the balls turn rcund their common pentre of giavlty C, it is evident, that the fmallei ball will perform a larger circle than the greater; in faft it will wheel round the orbit of the greater. So it is with the eaith revolving rouRd 'he fun; and \o with the moon wheeling round the earth. SECTION V. Day, Night, flW Seasons. ^ I. Diurnal Revolution.] Fig. 20. The earth is alfo obferved to tui^i round on its axis, at the fame time that it moves in its oibit round the fun : this revolution is performed in the fpace of twenty-four hours; as any part of its furface is turning to the fun, to that part the fun feems to rife ; and it is with them morning. Turned oppoHte to the fun, they enjoy noon. Turning from the fun, he feems to fet j and it^ il » * lO ELEMENTS OF P. I. is with them evening : turned from the fun, they are involved in flia- dow, which is night. 2. Heat i/iverj'e.] From the rotundity of the globe, the fun darts his rays diitdt on the heads of fome, while on others he ftioots his beams very obliquely : hence the polar regions ate rendered uninha- bitable through extreme cold, while the nations of tropical countries, or thofe direttly under the fun's lays, arc coloured black through in- tenfc heat. 3. Changing Day.] In the dilFercnt parts of the world, from the equinoctial to the poles, or terminations of the axis of the earth, their days and nights vary in length, from the fame caufe which produces the feafons. 4. Seafons.] Was the earth to move round the fun with its axis perpendicular to its orbit, a regular fucceflion of equal days and nights would uniforn)ly take place in the different parts of the earth; for the fun illumines half of the globe at once. Fig. 20. and every part of its furface would alternately experience a change of twelve hours light and twelve hours darknefs, from pole to pole ; but the earth is found to decline from the plane, E. Q^ Fig. 21, both northward and fouthward, and move in the orbit E. C. or the eclip- tic : hence the earth has day and night impartially and equally diftri- buted all over its furface, only when it is at Sp. or Aut in its orbit, where the equator and ecliptic interfeft each other. In its moving from V.'in. by Sp. to Sum>in its orbit, we, the inhabitants of the nor- thern hemifphere, will have the days increafing in length, and wea- ther growing warm ; while thole of the fouthern hemifphere, will ex- perience exidly the reverfe. In its moving from Sum. by Aut. to Win, ' we have days decreafing, and weather growing cold, while the inha- bitants of the fouthern hemifphere enjoy lengthening days, and in- creafing warmth. 5 Polar Day.] At the poles, day and night alternately fucceed each other, at intervals of fix months ; for all the time between the vernal and autumnal equinoxes, or while the earth is moving from fpiing to autumn, when the fun is no longer viiible at the fourh f ole, it gives continual day to the arftic regions ; and, the remaining part of the year, thofe dreary waftes are involved in ni^rht, while the antaiftic, or foulh pole, is in the glare »f peipctual day *. SECTION * The caufe ofthefe remarkable effe'ls may be earilyfeen in Fig. 11, «, 13. Let S. reprefent the Tun j the four globes, the earth in ditferent mm oi its orbit, leceiv' ing trom its changing pofition, the varying leafons of fpri , I'ummer, autumn, and «itiier, as it would appear to the eye fituatfd, Fig. ii. between the fun ami polar ftar; confequentiy, the pole of the earth towards the eye. Fig. ax. beyond the earth's orbit, at the autumnal equinox. Fig. 13. beyond the earth's orbit at the cftival folfiice, or midfummer. If the black fpot on the globes be fuppofed to re- prefent Ireland, wc'inay eafily fee how equally light and darknefs would be diftri- buted to it at the time of the equinoxes, or in fpring and autumn j howfmalla ftare of funfhine it would be turned inf) in winter; and how (hott a time it would be obfcured in Aade or night in fummer. Thefe things may he all pleafingly ex- hibited beyond all defcription, by an eify experiment. If a couple of hoops be fixed in the direftion of E. (^ and E. C. Fig. z». and a candle placed as at S. we may, by fttfpcnding an artificial ball from a thread, aiSp. from H. and moving it eafily •long the hwf £,C. be agreeably entrained with a p>etty miniature reprcfen< tatioa §. IV, ASTRONOMY. It SECTION VI. Definitions y the rays uf the candle (Iriking on it, as it rifes or falls in the difTeient parts of its crbit or hoop, and as it naturally revolves on its own axis, by its touching the hoop ; or we may make the fame exhibition without ufing the hoopi, by gently twifting the thread, to make out the viciflitudea pf night and day ; takiogcaie to raifeand lower the hand at proper intervals, to make out the changes fti the feafoas, as we carry the ball rouod the candle. * - 12 ELEMENTS OF P. I. 7. Ecliptic.] As our earth in the courfe of a year, moves round its orbit or ecliptic, the plane of which is oblique to that of the equinoc- tial, the fun in that lime feems to us to move in a contrary diredlion, in an orbit or ecliptic round the heavens, of the fame obliquity from tropic to tropic, interfering the equinoftial in two oppofiie points, and forming an angle with it equal to twenty-three degrees twenty- eight minutes, the fun's greatelt declination. 8. Zodiac ] All the planets move nearly in thedireflion of the eclip- tic ; and that fpace on each fide of it, which bounds their utmoft devia- tions, is called the zodiac. The Zodiac is a broad circle or belt, in the ilarry heavens; it is about fixteen degrees in breath. The ecl'ptic is a line which equally divides it in two all round. The zodiac is divided into twelve equal parts, called figns or con- ilellalions ; each fign contains thirty degrees ; and thefe (igns are named and noted in the following manner : Aries. Taurus. (jemini, » u Cancer. Leo. Virgo. Libra. Scorpio. Sagittaritis. Capricornus. Aquarius. Pifces. The former fix are called northern, and the l^tt«r fouthern, figns j be- caufe the former poflefs that half of the ecliptic, which lies to the northward of the equinotlial ; and the latter that which lies to the fouthward. The northern are our funmier figns ; the fouthern are our winter ones. 9. Meridians'] If we fuppofe a line extended from pole to pole, on our earth, cutting the equator at right angles, this would be a meri- dian ; for all the people who live on this line, would have noon or any other part of the day, at one and the fame lime. In the heavens alfo meridians cut the equinoftial at right angles, and terminate in points oppofite to the poles of the world. 10. Terrejhial Lat. l^ Lon^.] The latitude of a place on our earth, is its diftance north or fouth from the equinoftial line. The longitude its diftance eafl: or well from a meridian. Circles are divided, whe- ther great or fniall, into three hundred and fixty parts, called degrees; the greateft longitude cf a place, therefore, can only be one hundred and eighiy, the utmoft latitude ninety, degrees. The meridian for meafuring longitude from, on our earth, is not determinate or eftablidied ; and geographers generally fix upon that one, on which the metropolis of their own nation ftands. 1 1. Ajcenfton and Decimation] The right afcenfion of any heavenly obje6l, is its diftance from that meridian which paflts through the firft point of Aries; the declination is its diftance from the equi- nodial. 1 2. Points and Colures.] The cardinal points of the ecliptic, are the four firft points of the figns, Aries, Cancer, Libra, and Capricornus. Thofc of Aries and Libra, are called equinodlial points ; and thofe of Cancer and Capricornus, folftitial points. The meridians that pals through thefe four points, meeting at the poles, form two large cir- cle. * there, interfering each other at right angles ; tjiefe are called t.he equinoctial and lolditial colures. 13 Celejin/ AAT p. I. oves round its ^ the equinoc- rary direftion, 'bliquity from • 'pofite points, rees twenfy- of the eclip- itaioftdevia- r belt, in the he ecliptic is >gns or con- s are named Viigo. 'K us. Pifces. H figns ; be- Hes to the lies to the -rn are our o pole, on e a mcri- 2 noon or 'gles, and ur earth, ongitude 'd, whe- degrees ; hundred is not on that eavenly the filft • equi- are the corn us. lofe of It pals je cir- called s. vr. ASTRONOMY. 13 i 1 I / Celeft'tal Long. £s* Lat.'\ If great circles be imagined to cut the ecliptic at right angles, thefe will interfedl each other in two oppofite points of the heavens. Thefe points are the poles of the ecliptic, at nearly twenty-three degrees and a half from the poles of the world ; and the circles are called circles of longitude in the heavens. The latitude of any heavenly objefl, is its diftance north or foutii from the ecliptic. The longitude its diitance from that circle of longitude, which paffes through the lirll point of Aries *. 13. Finding the Latitiulc'] The latitude of a place on the earth is more ealily found than the longitude. It may be performed by the help of a quadrant and addition and fubtradion only, if we have a meridian line, or other certain means to know when it is twelve o'clock by the fun. By the quadrant (Fig. 24. PI. II.) we can find the height or altitude of any heavenly body above the horizon ; if it be the fun we hold the quadrant fo that his lays fliall pafs through two holes or fights fixed on D. S. ; but if any other objcft, we look at it through tiie fights along D. S. ; the plummet aad thread hang- ing from the angle S, mark its altitude on the arch C. D. The me- ridian altitude of any object is its greafelt altitude for that day, and when the fun is on the meridian, it is twelve o'clock bt the dial. The fun's meridian altitude is his noon day altitude, and ih all places north of the torrid zone, the fun is exadly fouth at noon, by which we may gain an idea of the other points of the compafs, for if we turn our faces to the fun at noon, the north point will be exadly behind us, the weft on our right hand, the eaft on pur left. If we take the altitude of the fun or a ftar on the meridian, and the fun or ftar be in the equinov5lial, that altitude fubtra<5led from ninety deg. leaves the latitude of the place, but if the fun be not on the equinotSial, fubtraft his declination if north, or add if it be fouth from or to the degrees of altitude, and the remainder or fum fub- traded from ninety dcg. tells the latitude. Thofe who have but very little acquaintance with the heavenly bodies may, by juft look- ing about them, form fome idea of the latitude of the place they may be in all over the world. If the fun be over their hekds at noon n they mufl be within the tropics ; on the contrary, if he either keeps Xlk l^' up or never rifes during that fpace, they are within the polar cir- cles ; even the temperature of the place alone might give them fome ,.- idea of their latitude. The north or fouth pole is eafilv pointed out in the heavens, they are thofe points which appear as centres of re'- volution to the ftars in their apparent diurnal irotions. If our fitii'- ation be on the equator, both thefe points or poles fiiall be in our horizon, if we recede from the line, one of thele poles ihall fink - from * The latitudes of the fixed ftars remain invariahly the fair e, but their longi- .' '; tudc encreafts at the ilow rate of one licgree in fcventy-onc yeais and a hall; this \'^ is not a motioa of the fixed ftars, butoi the ciiiiinoiiial points (fr )m whi'Ji we reckon the ftar's longitude) and which move bacuward at hat rate; this is called the precelfion of the equinoxes, which requires uboiit 25,740 years for :, one revolution through the twelve figus, in which tirre the pole of the car'h in ^;;^ pointing to the heavens will defcribe one circuit round the pole of the ecliptic. .;. ' - *B7 ^ --:'.'\ ^■j& >4 ELEMENTS OF P.I. H ; I from our view, the other (hall coniequently rife above the horizon, juft fo many, degrees as we are didant from the equator ; to afcer- tain the altitude of the pole is the fame as to determine our latitude. When we turn our backs to the pole and look towards the equator ; if the heavenly bodies feem to rife on our left hand and fet on the right, we are in a northern latitude or on the northern hemifphcre ; but if they rife on the right and fet on the left, we are in the fouthern. There are no liich fimple and eafy methods of judging of our longi- tude, whether it be eaft or weft, from any given meridian, the ap- pearances of the heavenly bodies (hall generally be the fame in any longitude, while we keep in one parallel of latitude. 14. F'tndng the Longitude."} All places that lie under one meri- dian have the fame longitude, and experience at qnce the fame hour of the day ; and as the difference of time between any two places is according to the diftance of their meridians from e^ch other, fo if we knew the difference of the hour in thefe two places at one in- ftant of time, it would only be another name for difference of longi- tude ; for if their difference of time be one-half, one-third, one- fourth, or any other part of twenty-four hours, i. e. of the time of one diurnal revolution, their difference of longitude, or the diftance of their meridians from each other, will be one-half, one-third, one- fourth, or a fimilar part of three hundred and fixty degrees, i. e. of a parallel of latitude, or a circle on the earth, in a diredion eaft and weft. To find our longitude ; befides finding the hour in the place where we arc, we muft know what hoar it is at fome diftant place, the latter we muft either have by fome exaft * timekeeper, fet to the time • Furniflied with a true going watch and a quadrant, if we fet out with the Greenland-men, Aippofe from London, and proceed towards the north ; the farther we advance in the voyage the more the pole will feem to rife in the heavens or iky, and hence we may know how far we have got to the north : if we find that noon is longer in coming on than we might expeft it, from the watch as rej^lified for the meridian of I^ndon ; or in other words, that tlie watch is too faft for the place we are in, this at once informs us that we have got to the weftward, or towards the American coaft ; on the other hand, if we have noon hefore it is iz by the watch, that is before it is noon in London, we may be fure we have got to the eaftward : If the difference between the watch and the time of the place we are ip be one hour, we have got fil.een degrees eaftward or weftward of the meridian of London, if two hours we have got thirty, and fo on in proportion We may leave the whak-fiihers, and effeft in imagination the vainly attempted paffage to the Pacific on the north, if we go right over the pole when we arrive at that point, the quadrant may as before inform us of our fituation ; the quadrant however will here be fuperfluous, as at one view we fliall fee we are in latitude 90°. the heavenly bodies, whether fun, moon or ftars, all feeming towhirl round ■us in circles parallel to the horizon ; here the mariRcr's compafs can no longer p prove » moft faithful guide; by it we can ice when it is at London, morning, nuon, evening or midnight. If when we know that it is 6 in the morning at London, we take our depar- ture from the pole, having the fun on our right hand ; if we keep fo travelling forward that the luminary Ihall by degrees take us in the rear, and againft twelve o'clock, or the noon of London, bedire«31y behind us; if we ftill continue tra- velling forward in the fame dire<5tion, the fun by degrees takes us on the left, till at fix, or the evening of London, we have it dircdtly on our left hand; if flill travelling forward, v*lien it is night in England we keep the fun before us, fir ft towards our left hand, at twelve direAly before us, and afterwards toward* our right hand :— or, if we be fuppofed travelling by fea, we may exprefs it in other words, if we keep the fun on our flarbeard bow when it is 3 of the morning by the watch, that is, in !,ondon; on our (larboard beumsat6, on our (larboard quarter at 9, right aftern at 12, or when it is noon at London; on our larboard quarter at 3, on our larboard beams at 6, on our larboard bow at 9, and right a head at 12, or when it is midnight at London : — this will be di- rc«Sly leaving the pole and proceeding towards the Pacific : this courfe will bring us up with the rcmotell ttrritories of the Ruflians in Siberia near the arc- tic circle, where we find Afia and America within a few leagues of each other j paflTing thefe ftralts and entering the Pacific ocean, we find when it is noon in London, or by our reckoning on the watch, that midnight darkncfs envelopes fhis oppofite part of the world, by this wc know we are in 180" longitude both eaft and weft from London, and by our quadrant we learn our diftance from the equator. As we proceed towards the (buth, the ftars of the northern hemifphere feem to dip below the horizon, and thofe of the fouthem appear to rife in the heavens. When we crofs the equator, the ardic pole feems to fink from our view, and the arnardlic pole feems to emerge from the deep. We have the moft fouthcrn rapes li Africa or America to double before wc can retwm home. If we ftccr caft f vr raerica, the day will feem to come or quicker and quicker , if weft for Africa flower and (lower, till having palled one of thtfe capes and got into the Atlantic, the day and our watch pcrfedlly agree. When this is the cafe, we know we are once niore on the meridian of London : We have by the afilftance of the quadrant to gain the lame latitude, and at the fame time by help of our watch, to keep on the fame meridian we fet out from, and this brings us back, after our ideal and moft folitary voyage, to perhaps the moft bufy and buiUing fpot in all the world. Thus, by a true going time-keeper the difficulty of finding the longitude would be removed. All works of art how- ever are liable to imperfedion from their ftrudlure, and befides thefe, the changes of heat and cold, with the different degrees of gravity in the different parts of the earth, and the motion of travelling, all thele militate againft the regularity of a time-keeper, watch or clock. One artift however, J. Harrifiin, has fo far fucceeded in an attempt after a machine that Ihould furmount thefe obfta- cles, and going regularly on, tell in every part of the world the time of the day in London, that it has been ufed with (atisfadion iu every longitude, and in perhaps every habitable latitude upon earth, by the late adventurers for dif- coveries ; and government has beftowed upon the maker of the inftrument the fum of 20,oool. as a reward for his labours and invention. i B 8 i6 ELEMENTS O F inffaritofabfo/utctimefroiTirf,. - ^' ^' n >!>=. calculation , b„, „,., ^'T ''^ '" »Pi'cara„ce diftr from ,"1 5!«^« '». .s „:,s already ^m^k'^"" ,"' """^ ''"wcen any ^ ' ^'- °"'y anutlKr „a,„. f./ .i™" ct il'rF-"'''-" »' ''™J^^ .0 .e of ,„„,. Ij 7'?^"'7 "'=y 'T-^ylk " ""-■'■ i-''-^ '■'=»a. and whici, the tTventy-fourtJi climate. ^•f Within s. vr. ASTRONOMY. >7 Within the polar circles, the longeft day encreafes not by half hours, but by days and months. Befides the circles alieady mentioned, which are in fome nieafure fixed and detciniinatc J there are others that vary according to the place of the oblerver. 1 6. Poles of the H^^ri, «.] The zenith is that point in the heavens dire6lly over liead. Th« nadir is that po-nt dirc6"tly oppofue the zc- '/ith ; tl^e zenith and nadir are the two poles of the iiori/on. 17. Hori)con.] Thf feiifible horixon is that apparent clicle in the heavens on a le\el with the eye, which limits or boii.Hls the view of the iptdator on the lea, or on an extended plane. The eye of the Ipettator is the center of his hoiizon. The matheniiticd horizon may be CQnfidcred as coincitling with the renl'ibk', ih< ] f' \\ Moon, Tides, Oblate Figure of t!;e Earth. As ihe moon accompanies the earth tIirouj;h its annual courfe, at the fame time alio moving round it in an oj bit, as the earth moves round the fun, this produces thule various phalcs ur appearances ob- fervable in the moon. 1. Phafes,] It is full moon, when the earth being between the fun and the moon, we fee alt the enlightened part of the luoon.^iiange^ When the moon being between us and the lun, its enli£,htened part is turned from us ; and half-moon, when the moon being in the quadra- ■ lures, as the aftronomers call it ; or half-way between the two other poiltions, we fee but half the enlightened pait. 2. Ecli/>/'es.] The eclipfes of the fun and moon, are produced in a fimilar way ; an eclipfe of the i toon, is when the earth, being in u direct line between the fun and moon, P'ig. 30. hinders the light of the fun from falling upon, and being refledled by the moon. If the light of the fun is kept off from the whole body of the moon, it is a toial eclipfe ; if from a part only it is a partial one. An eclipfe of the furt, is when the moou being in a right line be- tween the fun and the eaith, hindeis the light of the fun from coming to us. If the moon hides from us the whole body of the fun, it is a total eclipfe j if not it is a partial one. In Fig. 31. let S reprefenl the fun ; E the earth; and M the moon in the different parts of iis orbit. Here the balls P H in the outer circle, reprefent the different phafes, or appearances of ihe moon, in the different parts of its oibit, to the inhabitants of the earth. 3. Experiment.] All thefe phenomena iiuiy be prettily exhibited in an eafy experiment, with a candle and ball Tig. 32. Let S be a candle, reprefenting the fun; B. a ball, reprefentiug the moon : let the head of the obfcrver be confidered as the fnuation of the earth. If the ob- ferver carry M. round his head in an orbit, and keeping his eye on it, mark out the different phafes in the different parts of its orbit, at C it will appear a crefcent ; at F full iMoon ; at H half moon ; and at D dark moon or change. If his eye, the ball and candle, be all on a level, when M is at D, S will be eclipitd by it from his view : and when M is at F, M will be eclipled in the iliadow of his head. Hence we may fee, that lunar eclipfes can only happen at the time of full ; and folar ones, only at the change. If the moon moved in the fame plane or level with the earth, fhe fliould have an eclipfe every full and change ; but the plane of its orbit is oblique to that of the earth j and crolfes it an angle of five degrees and one-third. The points of their intcrfe^ion are called the nodes of the moon's orbit. 7'he nodes change their place every lunation ; they move nineteen degrees and one-third towards the wed every year, and therefore pafs round the heavens in eighteen years and two hundred and twenty-five days ; mimmx'mm.sr.ii'.. s. vir. ASTRONOMY. >9 ihe golden number of our Kalendars. And it is only when the nodes happen to be in a light hne with the fun and the eaj^th, that the Iblar iand lunar ccliplos take place; as the orbit of C i moon is not very many decrees oblique to that of the ecliptic, flie generally fliineJ without letting every fccond fortnight, on the arftic or antarftic parts I of our globe during their winter, and thusdiveififies the gloom of their y fix months night. / 4. Moon-Jbine .] As the moon reflets the light of the fun to the r earth, fo if the moon have its inhabitants, our earth, in like manner, 3 a^ts as a moon to them. And fo great a moon-lhinedocs it throw on the Sattelite, that it may be feen from the earth with the naked e^e. There are few but who have obfcrved of the moon, a while betore and after the change, when we can fee it only a little while in the morning or evening, we may then fee its whole body diftindly : One fide of it appears as a bright (lender crefcent ; but the principal part of it fcems of a dark or dull, and fcarcely diftinft hue. The bright part ot it is as the day-light of the moon ; the dark part as the moon- ihine reflected from the earth. We are told, that in Italy and other parts, wliere the air is clear, that the dark moon may be feen, or the moon at the change, when it rifesor fets with the fun. If this be the cafe, it muft be fro-.n the moon-fiiine or the light of the fun reflected on it from the earth. 5. Lunar Day,] If the ihoon be peopled, the lot of Its inhabitants appears in fume refpe^s ditferent from ours. The moon turns only once round on her axis, while ihe performs her orbit round the earth i one fide of it is confequently always turned towards our earth, and receives fuccefTively two weeks of moonihine from our earth, and two weeks ot fun. The other fide, it feems, muft be two weeks in conti- nual darknefs, and two weeks in conftant day. Their day and night tlien is a month in length j and they experience no diverfity of feafons as we do. 6. Ttlefcopk Ol'fer'Vathns.] The ttioon is fufficiently near us, to give us an opportunity of obferving with the naked eye, inequalities of its furface. By help of the telefcope, they have been diftinftly af- certained, and confidered as mountains and cavities, as land and wa- ter ; they have eveo got geographical names, after the iflands, coun- tries, and feas on our earth, though without regard to fituation or fi- gure, from the fliadows ptojedted on the furface of the moon, froni lis eminences or uiountains, aftronomers alfo calculated their heights; -j they werp conc^uded to be about nine miles high. From the clear ,j|l appearance of the moon, it was imagined there were neither clouds "nor vapours about it, from whence raio might proceed; that there was confequently a feries of fine feiene weather there. It was even thought probable, that the moon had not even an atmofphere, be- caufe the planets and ftars which were feen near it, had not their light refracted, as it is in palfiBg through our atmofphere. Later obferva- tions however appear to have been more accurate. The aftrono- mer Herfchell, whofe telefcope magnifies fix thoufand five hundred imes, has reduced her higheft mountains, by his calculations, to about two miles. It feems he has lately difcovered alfo three volcanos in the moon : the principal one at the time of obfervation, was in a part of her diik, not then illuminated ; be eftitnated its diameter at about ^' '■' ^ * -^1^ ■■ S% '■■■ •' ^^^^ 'J ! ia ElLEMENTSOP P. f, three miles. It »je£lcd great quantities ot* finoke and lava ; and its light was to corfiderable, as to illiimioatc ilie lulls in its vicinity. The next luiiiition, he repeated hrs oblcrvations with the greateft attenti- on, but law nothing ot'it. The other two fccincd eitlier to have been lately extiiiguiihed, or to threaten an tniinediate eruption. 7. 'Tides. I While it is by attiaition that the caith reninins a fuIiU ball, when otheiwife its paits would be thrown off fioiii its center by the rotatory motion which it has on its axis; »nd while it it kept in it!* orl)it by the centripetal force, when otherwife the centrifugal would thiow it off in a right line through the imnicnfity ol Ipace. The wa- ter in its vallies, or the lea, and the aimofphere that Turrounds it, be- ing fluids, they receive from thefe two forces particular impreinons, t»l which the firmer parts of it are not fufceptible. Of thefe the moft feiuarkable are the tides, which, while they are produced in the ai- mofphere as well as in the water, they appear to us the more diiliil£t in the latter. 8. ThfirCauff] If we fix a firing to the fide of a flexible circula? r-oop, and thereby fwing it round in a circle, PI. Il.Fig.j2. we readily conceive liow the pan next the hand would draw out or Iwell by the drawing of the llring; how tiie oppofite part would fly off or fweli, by the centrifu- gal forte, it being leaf! drawn in ; how the intervening parts of the hoop would hereby be deprefll'd or flattened. So it is with the ocean j that part of it which is immediately under the futi, israifjd by its attrac- tion up into a fwell ; that part of it which lies on the oppofite fide of the earth, being leafl: aitrafted, is thrown up into a fimilar fwell, by the mo- tion of tiie earth in its orbit, or by the centrifugal force : the moon is fo near the earth (two hundred and forty thonland luilesat a medium) in comparifon of the fun (near one hundred millions of miles) that the moon's atiiartion, and the accompanying centrifugal force, are to thofe of the fun as ten is to three. If we confider then the lunar tides as the principal ones, we lliall find them influenced by the folar tides, as fol- lows: at the full and change, the lunar tides ten, fliall be encreafed three, by the conjundtion of the lolarones; and a power of thirteen /hall influence the fea, and produce fpring tides; but at the quarters of the moon, or at the time of half-moon, the two luminaries coun- teradting each other's inJluence on the waters, the fun's power of three, fliall be taken from the rioon'sof ten, and leave only feveti operating upon the fea ; and hence neap tides (hall confequently take place. 9. Eurt/j J If inftead of fwinging the flexible hoop round in a circle, as m the former experiment, we fuppofe it whirled round witii velocity on one of its fides, as a centre, as in PI. 11. Fig .33. we may eafily con- ceive how this fide, and the fide directly oppofite, would become fiat ©r deprelTed, by the intervening parts of the hoop fwelling out from the center, as it is whirled round. So is it with the fea ; by the cea- irifugal force from the turning round of the earth on its axis, t"lie wa- ters of the ocean are thrown up many miles higher at the equator, than they are at the poles. We might hence be apprehenfive, that the countries within the tropics would be deluged with water ; but the faft is, the folid part of the earth itfelf has a correfponding fliape, Lcing rather flat at th% poles, and highefl: at the equator. The land ftnd water then of our globe is not an exaft fphere, but an oblate jpherhuid. A prolate fpherhoid is highefl: at the poks ; a lemon may • I ■4»»»WKW!W» iri--! s. vnf. ASTRONOMY. ft be confidered m a figure of this defcription ; an orange a£ a fpheroid ot the oblate kind. It is the tendency of gravitation or attraftion, to draw the waters down to the poles, and to lay even thofe countries that we live in, fome miles under water ; but this influence is nicely countel-afled by the centrifugal force, which perpetually keeps it heaved up to the equator. 10. Other tffeGt of its Diurnni Revolution ] Thefe forces aft in like manner upon other bodies, as well as on water; hence the fame bodies are of lefs weight at the equator than at the poles. Thefe effe^s are mod di(lin6lly obfervable in the motion of pendulums; pendulums of the fame length move flower on the equatorial parts of the earth (where they have in their defcent to combat with the greated motion or centrifugal force, from the daily rotation of the earth on its axis) than they do at the poles (where their gravitation is not counterafted by the daily rotation of the earth, and where, being nearer to its center, they are alfo more ftrongly at- tradled. A difcovery of this difference in the motion of pendulums^ or in the time of clocks in the different parts of the earth, appears to have firft given the hint, that the earth was not an exaft or perfeft fphere. Two companies of mathematicians were difpatched from France, one to meaiure the length of a degree on the meridian in Lapland, the other at the equator; and a degree of latitude was found fomething fKortcr at the equator, than it proved to be on the flatter parts of the earth near the pole; our globe was found to be an oblate fpberoid, and very nearly of the fame proportion as the ingenious Niewton had computed it to be, from his knowledge of the laws of the creation : the figure of our earth, however, differs fo little from that of a fphere, that It i ,ay be confidered as fuch in th*? common geographical computations, without any fenfible error. SECTION VIII. Planetary Laws, tiriii the Methods of imjejligating the Motion, Magnitude, aW Distances oj the Planets. 1, Motion of the Sun.] Hitherto we have con^dered the fun and the earth as regularly moving in circles round one common center of gravity ; however, as there are a number of planets in our fyftem, revolving continually, like our earth, round the luminary at different diftances from him, and in different periods of time; the fun may be more fitly confidered as agitated round their feveral centers-, accord- ingly as he is attracted by them in their different diredlions ; nor are their orbits round the fun perfecliy circular, but elliptical, the planets I'ometimes receding from, and fometimes approaching nearer to the fun. 2. Paths of the Planets ar.d Covins.] If a thread be tied loofely round two pms ftuck in a table, and moderately ftretched by a black- lead pencil, carried round in an upright pofition, aa oval or ellipiis [Infet] C 3 ^ will \t !:> ;i' . '■( %t E L E M E N T S O F P. I. will be defcribed by the point of the pencil ; the two points where the pins are fixed are called the focufes or foci : The orbits of all the planets are ellipfes, but to trace out their rercmblance the pins muft be put very near together, and the nearer the pins aie, the more will the figure refemble a circle. But in repr«fen .ing the path of a comet the pins muft be far afunder, and then the figure defcribed will be very long and narrow. The fun is fituatcd nearly in one focus of the orbit of every planet and comet. That place in any orbit which is r.eareft to the lun is called the perihelion, and the moft diftani part the aphelion. rianetary Lanvs.)^ There are two principal laws obferved in the folar fyftein, which regulate the motions of all the planets. Firft. The planets move through the arches of equal areas, (that is of equal portions of the planes of their orbits) in equal times ; when a planet in its orbit is receding from the fun, the attraction of the luminary more diredtly rounterafts its centrifugal force, and retards its velocity ; at length, the attraction prevails, and the planet begins to approach nearer to the fun : in this approach the attraction en- creafes, as before it counteracted the motion of the planet j the velo- city however' which it- acquires in its approach to the fun, is the very f"»rce which again makes it recede from the luminary. Thus it is kept, as it were, fwlnging to and from the fun— as it recedes, it is retarded by attraction, and kept from flying oif through the immenfity offpace; as it approaches its velocity is encreafed, and this velocity again throws it oif, and thus prevents it from falling into the fun. Second. The fquaresofthe periodical times of the planets, are as the cubes of their mean diftances from the fun ; hence the propor- tion of their diftances are ealily afcertalned, by comparing the times of performing their orbits : was the real dlftance therefore of any of them determined, the diftances of all the others might be thus ob- tained. By obfervations of the tranfits of the planet Venus over the fun in 1761, and 1769, we now know the real diftances of the planets from the fun much better than before, and when the dlftance of an object is known, there are cafy geometrical rules for deducing its real bulk, from its apparent fize. 3. Deception of the Sen/es] When nftronomlcal doCtrines are Hrft advanced to us, we liften with furprile, and naturally doiibt ; we afk, How can aftronomers mealiare the ftars. and tell their dilVAnccs, for they are quite above us and out of our reach ; and how can they tell that the earth turns round ? if we may btlieve our own fenfes, the earth ftands ftill, and the fun, moon and ftars daily rife and fet, to lerve us for the purpofes of light or of heat. Thofe who have failed in fliips or in boats, may well remember, when once they had got accuftomed to the motion of ths veffel, fo far from their L-ing ferMole of its progreflion, the objeCts that relatively were ftanding ftill, as the houfes, the trees, and the iliore, appeared to be in motion, while they themreh'es, and their veflel, fcenied to be quite at reft j the teftimony of our fenfes then alone is invalid and futile in philofophical enquiries, and muft be corrected by reafoning on the na- ture of things. 4. Cwreded by Rea/otiing.] If the moft prodigious weight and complication of artiBciai machinery that the powers of man could ^-^ . ^ invent ■,sf^ ■"?^. aBW^Jtnpc^ S. VIII. ASTRONOMY. «? >,•",*?■ invent and execute, were erefted before us ; if, among all the variety of motions that could be contrived in it, one fmall wheel, index, pointer br hand, fo minute as to reiiuire a luicrofcope to dilccver it, turned round on its center, in a fecond of time, while the larger wheels were days, months, or years, in turning on their refpedtive axes : it would certainly be moll prepofterous and unnatural to expeft, that the little microfcopic wheel lliould fuftain the whole, that it alone rtiould be fixed and fini), and that the prodigious weigiit and com- plication of ivachiaery, lliould be whijled round it every fecord. Thus unnatural, and lti!l irore inconfiftent with the laws of the crea- tion, appear thcfe theories in the eye of modern philofophy, which fuppofe that the earth ftands ftill, and that the myriads of globes aie perpetually v/hiiled round it every 24 hours; for a'.honomers find by obfervatiun, that our earth is in fizw* but as a fmall or dimenfionlefs point, if compared with the diftance of the fixed ftars ; and that everj our whole folaifylUni, is but as a minute fpot, in what is nightly feen of the creation. 5. Afcertainment of the Dljlances and Mngnitude of Obje^s.] To conceive how they alcertain the diliance and magnitude of the planets, will be difficult for thofe who are unacquainted with the fcience of geometry : perhaps, however, an idea of the principles on which their cal- culations are founded, may be gathered f'lom what is obfervable on ea. .h i and firfl, if walking along a ftraight road, we pafs my objetl on the right or left, as a tree or a tower ; if the objeft lies clofe to the road, a very liiile diftance will make a confiderable difference in its bearing from us ; at a very ihort diliance before we come up to it, it fball appetir almoll diredly before us, foon we flialt be abreaft of it, r.nd as fbon we A S T R O N O M Y. ^5 fun it about two thirds of our year ; its day is about as long as twenty- four cf ours, its feafons more diverfe than ours on earth, and it has been calculated to have mountains higher than thofe of the moon : when it is to the weft of the fun it is a morning-ftar, when to the eaft of him an evening-ftar. 4. Our Earth is the third planet in the order of the fjdem. It moves round the fun in 365 days ard nearly 6 hours, which is the origin of our civil year, and it turns round on its axis in the fpace of a day and night. The earth is attended by the moon, which moves round it in twenty-Cen days and eight hours, but from one new moon to the next twenty-nine days and an half. The moon's phafes are explained in page 1 8. 5. The Mars is the fourth planet from the fun, it is about one fifth as large as the earth, its day is nearly as long as ours is, it goes round the fun in fomething lefs than two of our years, and has no variety of feafons : when we pafs near it, it has a fiery appearance, and is often miftaken for a comet ; but when we are on the opf ofite fide of our or- bit, it appears fmall, and fcarcely to be diftinguiftieJ from a fixed ftar. 6. The Jupiter is the fifth planet in the order of our fyftem, and the largeft that has yet been difcovered, being near a-thoufand times as large as our earth, and five times the diftance from the fun that we are j fo enjoys but a twenty- fifth part of the light, heat and at- traction of the luminary »hat we do ; for the proportions of ihefc are inverfely as the fquares of the diftances ; four moons however fceni to cheer the inhabitants, if fuch there are, -^f this diftant planet ; it has no variety of feafons ; its year is equal to about twelve of ours, and yet our day is more than twice as long as its ; turning fo fwift on its axis, its figure becomes more oblate than that of the cajth, being more than fix thoufand miles longer in diameter from one fide of its equator to the other, than from pole to pole : *'-'is fwiftnefs of its diurnal motion, alfo draws its clouds and vapours into l^rcalts or lines over its equatorial parts, forming what is called Jupiter's beMf. 7. The Saturn is the fixth planet from the fun, and is near thirty years in going round him ; the length of its day is not yet afcertamed ; it has five moons or fatellites, continually revolving round it, befide* a broad thin ring, fet edgeways round it, but detached a confiderable way from it, which alfo reflefls light upon it : by thefe reflexions, and the direft light from the fun, it receives more light than two fuch full moons as ours would afFovd ; fo it feems likely it nmy have itihabitants adapted to the gloom, and coldnefs of its fituation. Among the various conjec- tures that have been made refpedling the very fingiilar appesvrance of the ring that accompanies this planet, fome have luppofed it to be the fragments, or ruins of its exterior original fViell, the reft of which has fallen down and formed the prefent orb ; if the ring itfelf be inhabited^ they mud have a day and night equal to near thirty of our years, as the fun fhines for almoft fifteen of our years on the northern fide of it, then goes ofF, and {hines as long on the fouthein fide Neither the Jupiter's, the Saturn's Moons, nor the ring can be feen without a telefcope. 8. The feventh planet in the order of our fyftem, was but lately difcovered by Herfchell, and called by him the Georgium fidus, or peorgian planet; it Is neatly twice as far diftant as the Saturn from , :' • the fe. E !• E M E N T S OP the nror ^ " ^"^ '"OOR be abfenr U.Hr " evening v fible to bits, by the conK "";^ ^"'^ ''ke them carried .' ^- '"'"S only in their Derfolf * '^^ *'""'^''' ^'o«Jd preferv^ ^^^r °''"'' '^ » while the l ^ ° prevent difturbances in lu r . the comet's orbi; "h' ^''^^^"o^e. they are flwavs /H?""," '^^"^ ''. UfiofthrcT't'"''''^^'^^ ^"^^ ^^"'"g into ^^'^''^'°"« Ji feems to have ,. ' " * ^' ,- - '■«_.•■-.* been S. X. ASTRONOMY. tf been his opinion, that as the comets are framed of a texture which difpofes them to fume and difcharge vapours in an aftonifhingly pro- fule or copious manner even at confiderable diftan-:es from the fun j for fome of them, when neareft to the fun in iheir orbits, have been yet farther diftant than feveral of the planets ; that the tails which they emit are g»^adually difperfed and fcattered through the planetary regions, and that the planets, as they roll along in their orbits, attraS this vapour to themfelves, which entering their atmofpheres, contri- butes to the renovation of the face of things, fupplying moifture to the globe, and renewing the viviiying quality of the air, whofe moft aftive arxi fubiile parts they chiefly fupply ; that the decreafe which the fun itfclf may fufFer, by fo long an eniiflion of light, muft be fup- plied by the cometi. The tremendous one of 1680, came fo near to I he fun, that it muft have been retarded by its atmofphere, if there be one round the luminary ; and will confequenily, approach nearer in its next defcent, meet with greater refiftance, and be again more retarded, till it will at length iuipinge on its furface, and ferve as fuel to that prodigious globe of fire. SECTION X. Conjectures of AsTRONOME RS. the Stars. Dijlance and Number of We may conclude this defcription of the folar fyftem, with juft mentioning fome refledions that have been made on it by aftronomers. I. CofijeSures.] The ledlurer, William Wjilker, has afTerted, that fo peifeft are the laws by which this wonderful fyftem is regulated, and fo cfFedlual that felf-phyfick which the Almighty has inftituted through all his works, that if any difturbance happens in the fyftem, there requires no immediate interpofition to prevent or cure the nv'*- chief J each body carrying within itfelf the principles of prefervat.on and cure. Enough has been faid on the eftabliflied laws of the fpheres, to fliow what he means ; he exemplifies it in the Jupiter ftill perfevering in an orbit, when drawn out of its former track by the comet of 1680. On the other hand, Newton obfervlng fome fmall inequalities In the inolion of the planets, thought that thefe muft increafe by flow de- grees, 'till they render at length the prefent frame of nature unfit for the purpofes it now ferves. This thought has been reprefented as impious ; and as no lefs than cafting a refleftion upon the wifdom of the Creator, for framing a perifliable work. In anfwer to this it has been replied, that the body of every animal fhews the unlimited wif- dom of its author no lefs ; nay, in many relpedls more than the larger frame of nature ; and yet we fee they are all defigned to laft but a fmall fpace of time; and that it is fufficient if it endure the time in- tended by its author. r*;^!' .' ^ .'Ia Whatever *"/ «» ■ •;*■: 'I »•**• ::n^' h' ''H ' 1!^ 43 ELEMENTSOF P.I. Whatever truth there may be, in the fpeculations of philofophers, with regard to the changes that niay happen in the bodies that He without our earth, we read in the icriptures of the end of the world, and of the end of time ; and however we regard it, we may continu- ally lee, that the world and time keep pafllng away on the children of men ; and that death foon clofes the tranfitory fcene of this life. Such is the lot of the inhabitants of our earth : But what is th« Con* dition of the worlds that furround us is unrevealed to us. 2. Dijiance.] The moon is dillant from the earth 240,000 miles, and by the lateft obfervations the fun's diftance is ninety*five millions of miles ; the planet Saturn is above nine times farther from the fun, and the comets in moving from their perihelion, go fo far beyond the mod diftant planet of our fyftem, that we quite lofe fight of them till they rejturn nearer the fun. But much farther than their greateft ex- curilon, as calculated by Aft^onomers (and the Periods of fome of them have been told) is the almoft unmeafurable diftance of the fixed ftars^ Far beyond the utmoft verge of our magnificent fyftem, and where our moon and planets would be invifible and our fun feem but a bright point,' ihine the innumerable multitudes of ftars ; thefe are called fixed, becaufe they wander not like the planets. Whoever fuppofes the fixed ftars placed in a concave fphere, as they appear to us, muft have a narrow and contracted idea of the works of creation, and the extent of the ftarry heavens ; for one ftar appears large, and another fmall ; becaule one is immenfely diftant in comp^irilon of another. The earth moves in an orbit of more than two hundred millions of miles in circumference ; yet there appears no fenfible difference be- tween its neareft and farthefc diftance from thefe remote bodies; ftill they appear to be in the fame (ituation, or at the fame diftance from lis ; ftill they appear to be of the fame magnitude, and to twinkle with the fame degree of brilliancy ; and the utmoft ftretch of the human imagination feems incapable of conceiving the imntenfity that lies between. J. Number.l Befides the ftars which are vifible to the naked eye, which aftronomers have divided into fix or feven claifes, accord- ing to their different apparent magnitudes, there are others which are called telefcopic ftars, from their being only difcoverable by means of the telefcope; an innumerable multitude of this kind of ftars, makes that brightnels in the heavens, which is called the galaxy, or milky way. By the laft improvements in the telefcope, 30,000 (thirty thou- fand) fixed ftars are difcovered. Many of them appear double; but they are only ftars at different dlftances from us, appearing nearly in the fame line. Some appear like a topaz ; others azure ; others red ; all are round, and many as pcrfeClly defined, as a (hilling on black cloth. 4. Starry Heavens] As the ftars, contrary to the moon and planets, fhine like our fun, by their own native light ; aftronomers imagine, that each of them is a fun, with its fyftem of inhabited worlds revolv- ing round it, though invifible to us from their immenfe diftance from us. Some of thofe called fixed ftars, have a progreffive n;iotion : fome of them appear to change their magnitudes : new ones feem to rife into view, increafe in magnitude, and then diminifh, and vaniih out 1* S. X. ASTRONOMY. 29 out of fight. From ihefe appearances in the ftariy heavens, it has been thought probable, that lyllenis may revolve round fyfteins : that our fun hiuifelf is in motion, ami carries his fyftem of worlds along with him : that funs and fyftems are created remote from us, endure for a time, and then are diffoived : that fome of the Oars may be fo remote from ours, that their light may not have reached our eaith ever fince the creation : that could we launch out into fpace, and fly to the mort ditlant liar we can now fee, even there we Ihould find our- felves on the confines of creation, and fee as many ftars before us as we left behind : that fpace is infinite, without top or bottom. Well in- deed may it be faid, that the human underilanding is bewildered in the contemplation of the wonders of the firmament ; that the giddy fancy turns round, and is entirely lofl and funk in the abyfs of creation. f P AR T^ ;^- ^ 1,' . < '■' i: "■■^ -■ ^J'l'ft! t 30 J Ik" A !• A R T 1/. THE V O N o M Y o r THE Yj^yj ^ '^^"^^ INANIMATE. H platlS^S.;^!! "■'"'"^''- '^.^"^e of the earth and conr {"^'H. and ihe coS b oV d,. r ''^/'■STS '^^ vicilfitudes ofdav ""l 0.^. . i...enced t^^ ^ ^^ tj!;;:^; -'f<^-' t's — u, aa awfui ..d i.,,,,,,, t^f J,^^^;;;;^;;;^ u.ud thac ca^ SEC T f o NT I. Sublunary Thi^cs, P„,,„., prehenfion. ^ J , plains or ,awif ""i ""' '*)' '™U'.t".s ^u, „ ,"" "."S'">' """d the ■Jflp««nM*^^^^*>^ -r-^ 'Vm-« #? s I. SUBLUNARY CREATION. 3« ihe earth ; of countries laid under the rolling waves of the ocean ; and of lands riling from the uiidlt of the waters, and becoming the habitations of beufts and of nicn : lb tranficni and uncwiain are all earthly things. %. 'Their otifjn.] There was a time when man lived in paradife, un- niolelbd by the outrages of the natuml woild, and undifturbed by ihe rtill more dreadful tumults of a difordered nnnd. When he had givcQ hiui tor meat every herb bearing feed, which was upon the face of all the earth ; and every tree in tlic which was the fruit of a tree yield- ing feed ; when to every beaft of the earth, and to every towl of i:he air, and to every thing that crept on the earth, wherein there was life, were given eveiy green heib for meat ; and it was lb ; and every thing that was made behold it was very good. But Adam de- parted from the commands of his Creator, and the ground was curfed for his fake { thorns alfo and thiftles it brought forth ; in forrow he was condemned to eat of it all the days of his life ; and in the fweat of his face to cit bread, till he returned to the ground from whence he was takirn. Yet however the earth may have been defolated by this dreadful revolution, whatever difurders may have been iniro-