THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 OF CALIFORNIA 
 
 LOS ANGELES
 
 
 /Mi
 

 
 A N 
 
 ESTIMATE 
 
 OF THE 
 
 TEMPERATURE 
 
 O F 
 
 DIFFERENT LATITUDES, 
 
 By RICHARD KIRWAN, Efq. F. R. S. 
 
 AND MEMBER OF THE ACADEMIES OF STOCKHOLM, UPSAI-, 
 DIJON, DUBLIN, FH 1 L AD E L PH 1 A, &C. 
 
 LONDON: 
 
 PRINTED BY J. DAVIS, 
 
 FOR P. ELMSLY, IN THE STRAND. 
 
 M.DCC.tXXXVU.
 
 R E F A C E. 
 
 METEOROLOGY, like every other 
 branch of true philofophy, dates its 
 origin from the beginning of the laft century. 
 However defirous the ancients might have 
 been of cultivating this fcience ; the want of 
 inftruments neceflarily denied them all accefs 
 to it. Drebbel, by the invention of the ther- 
 mometer, and Torricelli, by that of the baro- 
 meter, undoubtedly, gave birth to it. From 
 the very origin of the different literary fo- 
 cieties of Europe, feveral of their moft dif- 
 tinguifhed members applied themfelves to its 
 improvement : but from the difcordant mul- 
 tiplicity, as well as imperfection of the inftru- 
 ments then in ufe, the narrow limits to which 
 individual obfervations were confined, whofe 
 importance depends on a knowledge of their 
 extent, the interruption, either by death, 
 ficknefs, or the common cares of life, of a 
 feries, whofe perplexed concatenation can never 
 be traced, but by an uninterrupted view of 
 its fucceffion, fuch difcouraging impediments 
 arofe, as put a period to all theoretic inquiries 
 for many years. There is no fcience in the 
 a whole
 
 IV PREFACE. 
 
 whole circle of thofe attainable by man, which 
 requires fuch a confpiracy^ if I may fo call it, 
 of all nations, to bring it to perfection as Me- 
 teorology ; nor is there any, perhaps, more 
 conducive to his fecurity and comfort. It is 
 not fufficient that obfervations fhould be made 
 in one city, in one kingdom, or even in 
 one hemifphere ; but fimultaneous obferva- 
 tions muft, if poflible, be procured in all 
 degrees of latitude, and longitude, in each 
 hemifphere, in order that the correfpondence, 
 and connection of the phenomena may be 
 perceived. But in the prefent ftate of things, 
 to expect all nations to be fo fenfible, and at- 
 tentive to their true happinefs, would indeed 
 be extravagant ; fome ages of civilization muft 
 firft elapfe. The only fovereign who hath 
 hitherto diftinguifhed himfelf by his attach- 
 ment to this fcience, and thereby infured to 
 his name the refpect, admiration, and gratitude 
 of the lateft pofterity, is that truly wife, and 
 excellent prince, CHARLES THEODORE, 
 Elector Palatine of the Rhine ; who not only 
 erected an academy in his own principality, 
 folely dedicated to meteorological inquiries, 
 but has alfo fent the beft inftruments fubfer- 
 vient thereto, fabricated at his own expence, 
 to all the academies and univerfities of Europe, 
 willing and able to undertake the tafk of em- 
 ploying them. 
 
 From the diffufion of that enlightened wif- 
 
 dom, which already dawns upon almoft every 
 
 i European
 
 PREFACE. V 
 
 European nation, and the cleferved contempt 
 into which the favage military prejudices of our 
 anceftors, the refult of pride, ignorance, cruelty, 
 and injuftice,are daily finking, it is to be hoped, 
 that other fovereigns will not be long inatten- 
 tive to this object, fo palpably connected with 
 the interests of commerce and agriculture, the 
 great fources of the wealth and happinefs of 
 their refpective nations. This fcience differs 
 indeed from other branches of natural know- 
 ledge in this ; that it does not enable us to 
 alter the fpontaneous courfe of nature, except 
 in a very few cafes *; but, being brought to 
 perfection, it would, like aftronomy, enable 
 us at leaft to forefee thofe changes we could not 
 prevent. If from the prefent ftate of the at- 
 mofphere, the tiller of the foil, or of the main, 
 could forefee, or have a table- prefented to him 
 of the changes it would undergo for fix, or 
 even three months, with what confidence and 
 fecurity would not each of them be enabled to 
 direct, and purfue their refpective operations ? 
 Great as is the diftance between fuch know- 
 ledge, and our own 'prefent attainments, we 
 have no reafon to think it above the level of 
 the powers of the human mind. The motions of 
 the planets inuft have appeared as perplexed 
 and intricate to thofe who firft contemplated 
 them ; yet by perfevering induftry, they are 
 now known to the utmoft precifion. The 
 
 * Such as the alteration of temperature, by promoting or 
 checking vegetation, draining morafles, &c. 
 
 prefent
 
 VI PREFACE. 
 
 prefent is (as the great Leibnitz exprefles it) 
 in every cafe pregnant with the future, and the 
 connection muft be found by long and atten- 
 tive obfervation. 
 
 The firft ftep in this comprehenfive inquiry, 
 feems to me to be the knowledge of the tem- 
 perature of the globe, in every latitude. It is 
 the change of temperature that chiefly occa- 
 fions the viciffitudes of winds ; thefe in their 
 turns, influence the temperature, and both to- 
 gether form the ftate of the atmofphere. Elec- 
 trical agency, undoubtedly, interferes; but 
 ftill the temperature affects this alfo, as it 
 does, the rife, fall, and quantity of vapours, 
 and every other aerial meteor. 
 
 The fads contained in the following Eflay, 
 were collected from the memoirs of the dif- 
 ferent academies of Europe, and particularly 
 thofe of the Academy of Medicine, lately eredt- 
 ed at Paris, in which the meteorological part 
 is ably conducted, by the celebrated Abbe de 
 la Cotte. The differtations of that moft in- 
 genious philofopher, Mr. Du Carla, fome of 
 Mr.Wargentin's, and the excellent Treatife on 
 Thermometers, by Mr. Van Swinden, were 
 particularly ufeful to me. I had frequent rea- 
 fon to lament the difficulties uncautioufly fu- 
 peradded to this intricate fubjecl:. It is a mat- 
 ter of furprife, that philofophers have not as 
 yet agreed on one fort of graduation for their 
 thermometers: befides that of Fahrenheit, there 
 are now three in ufe on the Continent, that of 
 
 Reaumur,
 
 PREFACE. Vll 
 
 Reaumur, the Swedifh, and that of Delifle. 
 The time requifite to reduce all thefe to one 
 ftandard, where the obfervations are numer- 
 ous, is immenfe ; and the three laft are much 
 more inconvenient for calculation than that of 
 Fahrenheit, as, from the narrownefs of their 
 fcales, they prefent more fractions, and ex- 
 prefs degrees under congelation, by the nega- 
 tive fign ; to this laft inconvenience, indeed, 
 that of Delifle is not fubjecl: ; but then its courfe 
 is retrograde to that of all the others: the 
 commencement of its fcale is variable, and 
 neceflarily leads to miftakes.* The divifion 
 of degrees into lines, and the fub-divilion of 
 thefe into twelfths, inftead of the decimal di- 
 vifions, is another inconvenience in barometri- 
 cal obfervations, which might eafily be avoided. 
 It were alfo to be wiihed, that the fituation of 
 places, their latitude and longitude, the pofi- 
 tion and diftance of the neareft feas, lakes, 
 forefts, mountains, &c. were accurately noted, 
 and their uiual names given inftead of Latin 
 names, which are not to be found in maps, and 
 difficultly known to foreigners. The general 
 defignations of hot, cold^ wet, dry, &c. are- 
 vague, and prefent no fort of idea, when no 
 ftandard is given, to which thefe appellations 
 
 * Would it not be proper to conftrucl a thermometer, 
 beginning at the congelation of mercury, and terminating 
 at the ebullition of water, which might then contain 250 
 degrees ? This I fubmit to the confideration of the illuf- 
 trious Meteorological Academy, of Manheim. 
 
 may
 
 Vlll PREFACE* 
 
 may be referred. This ftandard can be no 
 other, than either the mean of the ufual 
 quantities in every country, or that which 
 by experience is found to be moft neceflary for 
 its cultivation and fubfiftence. Nocturnal ob- 
 fervations feem to have been intirely neglected; 
 yet furely they are as neceffary as the diurnal : 
 this mews the neceffity of fome public eftab- 
 lifhment for meteorological inquiries. Bal- 
 loons of a fmall fize might be advantageoufly 
 ufed, to dif cover the currents that obtain in the 
 upper regions of the atmofphere ; and if thefe 
 were attended to, particularly about the time 
 of the ^Equinoxes and Solilices, pretty fure 
 prefages of the enfuing feafons might be had. 
 
 The mafs of obiervations already mentioned, 
 I have endeavoured to turn to fome ufe, in 
 order to pave the way for a theory of winds : 
 the obfervations, in many places, were indeed 
 too few, and the topography of feveral others 
 too little known to me; however, I flatter 
 myfelf I have traced a plan, according to 
 which a more perfect ftructure may hereafter 
 be reared. 
 
 CHAP.
 
 CHAP. 
 
 OF THE 
 
 S O U R C 
 
 HEAT AND COLD. 
 
 THAT the prefence of the fun is the prin- 
 cipal fource of heat as well as of light, 
 and its abfence of cold, is too obvious to have 
 been ever doubted; neither have mankind been 
 long ignorant of the effect of the greater or 
 lefler obliquity of its rays. TJie flighteft at- 
 tention to their fenfations during the fhort 
 period of 24 hours was fufficient to inftrudt 
 them fo far ; but the immediate and moil 
 plaufible inference from this fimple obferva- 
 tion, though aflented to for a feries of ages, 
 was fully refuted by fubfequent difcoveries. 
 The philofophers of Greece and Italy (the only 
 whole writings have been tranfmitted to us) 
 B obfcrving
 
 2 Of tie Sources of Heat and Cold. 
 
 obferving that in the Summer months, during 
 which in their latitudes the fun at mid-day is 
 often nearly vertical, the heat was very in- 
 tenfe, and that in Winter, when its meridian 
 altitude was leaft, the refulting cold was equally 
 confiderable, haftily concluded th^t, between 
 the tropics, where its altitude moft part of the 
 year is nearly vertical, its heat muft be in- 
 tolerable, and, for oppofite reafons, they judged 
 the countries within the polar circles uninha- 
 bitable*. Time among other errors has re- 
 moved this ; but, as ufually happens, it has 
 brought forward other phenomena equally 
 difficult to explain. The hotteft days are 
 frequently felt in the coldeft climates, and 
 reciprocally the coldeft weather, and even per- 
 petual fnow, are found in countries bordering 
 on, or even immediately under the equator. 
 In the fame latitudes very different tempe- 
 ratures have been obferved, not only in dif- 
 ferent, but even in the fame hemifphere. The 
 temperature of the eaftern coaft of North 
 America differs widely from that of the weft- 
 ern oppofite coaft of Europe, but agrees nearly 
 with that of the eaftern coaft of Afia lying be- 
 tween the fame parallels j* ; thefe, and feveral 
 other phenomena of the fame nature, lefs 
 remote from us, clearly mew we muft recur 
 to fome other caufes befides the immediate 
 agency or abfence of the folar rays. 
 
 * Plin. Lib. II. cap. 68. f Vol. I. Mem. Philadelph. 
 
 The
 
 Of ihe Sources of Heat and Cold. $ 
 
 The celebrated Halley has indeed proved 
 that, abftracting from the intervention of fogs, 
 mifts, and mountains of ice, the hotteft wea- 
 ther might in Summer time take place even 
 under the poles, the duration of the Sun's light 
 more than compenfating for the obliquity of 
 its direction ; for it is evident that a weak 
 force acting for a long time, may produce as 
 great or a greater effecT: than a ftronger force 
 acting for a fhorter time : but as thefe abftrac- 
 tions are never realized, and many phyfical 
 caufes conftantly obftruct the activity of the 
 folar rays in thefe and other regions, the ne- 
 ceffity of recurring to fome other caufe ftill 
 remained, until Mr. De Mairan removed the 
 veil * ; to him we owe the difcovery, that the 
 rigour of the Winter's cold is tempered by the 
 heat imparted to the atmofphere by the earth 
 itfelf : this heat, he ftyles, in common with 
 fome celebrated philosophers of this day, a 
 central emanation, thinking it proceeds from 
 fome mighty mafs of fire or he,at in the center 
 of the earth ; a fuppofition that appears to me 
 both groundlefs and needlefs. The earth and 
 water were created together, and water, even 
 before the formation of the fun, was in a 
 liquid ftate, and confequently muft have pof- 
 fefled at leaft 32 of our thermometrical de- 
 grees ; nor could the earth be devoid of heat, 
 otherwife the water would have been fpeedily 
 
 * Merrt. Par. 1719 and 1767, 
 
 B a con-
 
 4 Of the Sources of Heat and Cold. 
 
 congealed. It appears then, that the globe 
 from its very origin pofleffed the heat necef- 
 fary for the purpofes it was intended to ferve : 
 this heat indeed would have been long loft, had 
 it not been preferved and renewed by the in- 
 ceffant influence of the Sun, to which one 
 half of its furface is conftantly expofed. But 
 $s no authentic obfervation informs us that 
 this heat increafes in proportion as we pene- 
 trate below the furface of the earth, but on 
 the contrary, many {hew it to decreafe (though 
 never to lefs than 36), and that its variation 
 at the fame diftance below the furface, con- 
 Jiantly keeps pace with the variation of the 
 iohir heat on the furface, it feems evident 
 that it is to this planet alone, it owes its con- 
 tinuation. 
 
 r The difcovery of Mr. De Mairan in great 
 meafure removed the difficulty of explaining 
 by what means the Winter's cold is ib far 
 tempered, as to render the colder climates in- 
 habitable ; but it went no further ; we were 
 ftill at a lofs to know the mean annual, or 
 monthly temperature of thefe latitudes. I 
 fay the mean or average temperature, for no 
 other is an object of icience, as no two fuc- 
 ceeding years exactly agree in temperature. 
 He has, indeed, with great fagacity, calculated 
 the maximum and minimum of heat in every 
 latitude, for the Summer and .Winter folftices; 
 but fo many phyiical caufes intervene, that the 
 events feldom or ever coincide with his cal- 
 culations, as he himielf candidly owns. 
 
 The
 
 Of the Sources of Heat and Cold. 5 
 
 The famed aftronomer Tobias Mayer, of 
 Gottingen, in a few pages did more for re- 
 folving all the difficulties that occurred on 
 this fubject, than any of his predeceflbrs *. 
 He iirft pointed out to meteorologifb, the ne- 
 ceffity of following the method long ufed by 
 aftronomers, namely, of firft rinding the mean 
 of certain large periods, as years and months, 
 gradually correcting the errors that may be 
 difcovered, and afterwards rinding an equation 
 whereby to correct aberrations arifmg from 
 height and fituation. He even proceeded fo 
 far as to give an equation to correct the effects 
 of height, which in many cafes approximates 
 very nearly ; but his moft important difcovery 
 feems to me to have been the equation,,by which 
 knowing the mean annual temperature of two 
 latitudes, the mean annual temperature of every 
 other latitude, and even of the pole itfelf, may 
 be found: this equation, which he has ob- 
 fcurely and fummarily delivered, I mail give 
 more at large in the following pages. 
 
 The defects of Mr. Mayer's method are, 
 i. That he does not point out the particu- 
 lar fpace his determinations refpect, and it is 
 evident they do not indifcriminately take place 
 every where, for inftance, in no part of Ame- 
 rica. 2dly. That he has given no equation to 
 correct the calculation of the temperature of 
 places diftant from the lea, nor is his equation 
 
 * Oper. Ined. Vol. I. 
 
 B 3 for
 
 6 Of the Sources of Heat and Cold. 
 
 for height fufficiently exact. 3dly. That he 
 gives no account of the monthly temperature. 
 4thly. That he is totally filent with regard to 
 the eaftern coafts of Afia, America, and the 
 fouthern hemiiphere : thefe, and fome other, 
 I mall endeavour to fupply. 
 
 The next fource of heat is the condenfatioa 
 of vapour. It is well known that vapour con- 
 tains a quantity of the matter of heat, which 
 produces no other effect but that of making it 
 affume an aerial, expanded ftate, until the vapour 
 is condenfed into a liquid; but during this con- 
 denfation a quantity of fenfible heat is fet 
 loofe, which warms the furrounding atmo- 
 fphere. This condenfation is frequently caufed 
 by the attraction of an electrical cloud, and 
 hence the fultrinefs we frequently experience 
 before rain. 
 
 As the earth is the chief fource of heat 
 in the atmofphere that furrounds it, diftance 
 from the earth is a fource of cold ; or, in other 
 words, the greateft cold muft prevail in the 
 higheft regions of the atmofphere, and fo 
 much the greater, as clear, unclouded air, feems 
 to receive no heat whatsoever from the rays 
 of the Sun, whether direct or reflected. Thus 
 if the focus of the moft powerful burning 
 glafs be directed on mere air, it does not 
 produce the fmalleft degree of heat ; and the 
 reafon is, becaufe the air being tranfparent, 
 affords a free paflage to the rays of light, 
 which act as fire only when confined within 
 
 the
 
 Of the Sources of Heat and Cold. j 
 
 the minuteft interfaces of bodies ; as it is then, 
 and then only, that they counteract the at- 
 tractive power of the particles of matter; in 
 which action and re-ation heat confifts. 
 
 Hence the higheft mountains, even under 
 the equator, are during the whole year covered 
 with mow, Mr. Bouguer found the cold of 
 Pinchinca, one of the Cordelieres, immediately 
 under the line, to extend from 7 to 9 degrees 
 under the freezing point every morning before 
 funrife ; and hence at a certain height, which 
 varies in almoft every latitude, it conftantly 
 freezes at night in every feafon, though in the 
 warm climates it thaws to fome degree the 
 next day : this height he calls the lower term 
 of congelation: between the tropics he places 
 it at the height of 15577 ^ eet ' 
 
 But in lat. s8 he thinks it mould com- 
 mence, in Summer time, at the height of 13440 
 feet from the level of the fea. Suppofmg that 
 to be the height of the Pic of Teneriffe, and 
 that this mountain was covered with fnow in 
 Summer, both which luppofitions the chevalier 
 La Borde has fhewn to be erroneous, the 
 determination of the height of the lower term 
 of congelation I take to be of great confe^- 
 quence in meteorology, and therefore mall 
 give a table of it for every 5 9 of latitude. 
 
 At ftill greater heights it never freezes, 
 
 not becaufe the cold decreafes, but becaufe 
 
 vapours do not afcend fo high ; this height 
 
 Mr. Bouguer calls the upper term of congelation, 
 
 B 4 an4
 
 8 Of the Sources of .Heat and Cold. 
 
 and under the equator he fixes it at the height 
 of 28000 feet at moft*. 
 
 Under the equator, there being very little 
 variety in the weather, the height of both 
 terms is nearly conftant ; under other latitudes, 
 this height is variable, both in Summer and 
 Winter, according to the degree of heat which 
 prevails on the furface of the earth. But as 
 there is a mean annual temperature peculiar to 
 each latitude, fo there is a mean height for 
 each of thefe terms peculiar to each latitude. 
 And if we take the differences between the 
 mean temperatures of every latitude, and the 
 point of congelation, it is evident, that what- 
 ever proportion the difference under the equa- 
 tor bears to the height of either of the above 
 terms, the fame proportion will the difference 
 peculiar to every other latitude bear to the 
 height of thofe terms : for a moderate heat 
 diffuies itfelf in the fame manner as a great 
 heat, and the diflance to which their activity 
 extends, will be proportioned to the intenfity 
 of each. Thus the mean heat of the equator 
 being 84, the difference of this and 32, is 52. 
 And the mean heat of lat. 28 being 72,3, the 
 difference between this and 32, is 40,3. Then 
 as 52 . 15577 : : 4>3 J 2072. In this man- 
 ner, I have calculated the following Tables, 
 which I have inferted here, as the propereft 
 
 * The meafures of every kind mentioned in this Effav, 
 are reduced to thofe in ufe in England. 
 
 place,
 
 Of the Sources of Heat and Cold. 9 
 
 place, though fome of the principles on which 
 the calculation is founded, have not yet been 
 given, but may be feen, page 1 7. 
 
 
 Mean height 
 
 Mean height 
 
 
 Mean height 
 
 Mean height 
 
 
 of the 
 
 of the 
 
 
 of the 
 
 of the 
 
 
 Lower Term 
 
 Upper Term 
 
 
 Lower Term 
 
 Upper Term 
 
 
 of 
 
 of 
 
 
 of 
 
 of 
 
 
 Coli gelation. 
 
 Congelation. 
 
 
 Congelation. 
 
 Congelation. 
 
 V c r -r 
 
 
 
 J 5577 
 
 2800O. 
 
 45 
 
 7658 
 
 r * T. 
 13730 
 
 5 
 
 *5457 
 
 27784 
 
 5 
 
 6260 
 
 II 2 53 
 
 10 
 
 15067 
 
 27084 
 
 55 
 
 49 I2 
 
 8830 
 
 15 
 
 14498 
 
 26o6l 
 
 60 
 
 3 68 4 
 
 6546 
 
 20 
 
 *37f 
 
 24661 
 
 65 
 
 2516 
 
 4676 
 
 2 5 
 
 13030 
 
 23423 
 
 ?o 
 
 1557 
 
 2809 
 
 30 
 
 11592 
 
 20838 
 
 o 
 
 75 
 
 74 8 
 
 1346 
 
 35 
 
 10664 
 
 19169 
 
 80 
 
 120 
 
 207 
 
 40 
 
 9016 
 
 l62O7 
 
 
 
 
 In this manner, the height of both terms of 
 congelation may be calculated in every latitude, 
 for every degree of heat obferved at the fur- 
 face of the earth, on which it evidently de- 
 pends ; for when that is at 32, it is evident 
 the lower line of congelation is alfo on the 
 furface. 
 
 Hence knowing the height of the lower 
 term of congelation in any latitude, and alfo 
 the general temperature at the furface of the 
 earth *, the decrement of heat at any lower 
 
 * This is not eafily known, for it is the mean refult 
 of a number of obfervations made over a large extent, and 
 of confiderable duration. 
 
 height
 
 io Of tie Sources of Heat and Cold, 
 
 height may be known. For heat is obferved 
 to diminifn in afcending into the atmofphere, 
 nearly in an arithmetical progreffion ; and in 
 this cafe, we have the firft and laft terms ; and 
 if we make fo many terms in the progreffion, 
 as there are hundreds of feet in the diftance of 
 the line of congelation, we have all that is 
 requifite to find the decrement at each term. 
 
 Then let L = the intire decrement, or dif- 
 ference between the heat 
 at the furface and 32. 
 D := the diftance of the lower line 
 of congelation, in feet. 
 
 n = the number of terms = 
 
 d the firfl decrement 
 
 Jl = the rank of any given term $ 
 whofe decrement is re- 
 quired, 
 
 Then the decrement at any given term 
 ~ R d\ and by fubtra&ing this from the 
 heat at the furface, we have the heat at that 
 given height. The temperature at the up- 
 per term of congelation, may be inveftigated in 
 the fame manner, or that of any other height 
 in the atmofphere, except over mountains ; for 
 the air over mountains is generally wanner 
 than air of the fame height over the fea, or 
 over plains. 
 
 2 In
 
 Of the Sources of Heat and Cold. i \ 
 
 In the neighbourhood of Paris, lat. 48 ? 5o, 
 the temperature of the atmofphere near the 
 earth being 47, that, at the eftimated height 
 of 11084 feet was found by the intrepid 
 Charles, 21, or 11 below congelation. 
 
 Near Dijon, lat 47, on the 25th of April, 
 the temperature near the earth being 56, Mr. 
 Morveau found it, at the height of 10631 
 feet, to be only 26. It is true, that on the 
 1 2th of June, he found his thermometer heat- 
 ed to 70, at the height of 5280 feet ; but his 
 balloon was exceedingly heated by the direct 
 rays of the fun. 
 
 Lord Mulgrave, at the foot of Hackluyt hill, 
 lat. 80, found the temperature of the lower 
 air to be 50, that, on the fuminit of the hill 
 being 42 : its height was 1503 feet. 
 
 Sometimes the temperature of the upper 
 air is higher than that of the lower, particularly 
 when a large mafs of vapour is condenfed by 
 electrical agency ; for no part of the heat given 
 out by that caufe being loft by communication 
 with air much colder, that which furrounds the 
 vapours fo condenfed, muft be heated to a 
 confiderable degree. Air rendered opake by 
 clouds, tranfmits lefs, and confequently ab- 
 forbs more light, and is therefore more heated 
 than clear air. Sometimes winds, in oppofite 
 directions and different temperatures, flow at 
 different heights, the uppermoft being often 
 the warmeft ; all which circumftances, parti- 
 cularly in cloudy weather, render all calcula- 
 tions
 
 1 2 Of the Sources of Heat and Cold. 
 
 tions of the height of the terms of congelation, 
 on any particular day, precarious, though 
 when they regard a particular month or feafon, 
 they may be fufficiently exact. 
 
 The next general fource of cold is evapora- 
 tion ; for the attraction of the particles of 
 liquids decreafes as their points of contact 
 diminifh, and thereby their capacity for re- 
 ceiving the matter of heat, (which is the fame 
 as that of light) increafes ; by this increafed 
 capacity, the matter of heat or fire contained 
 in the neighbouring bodies,which, like all other 
 fluids, flows where it finds leafh refiftance, is 
 determined to flow towards the vapour ; and 
 confequently thofe bodies are cooled, though 
 the vapour is not heated ; becaufe the re-action 
 of its particles is barely equal to that which 
 it had before its capacity was increafed. 
 
 With refpect to evaporation, we may re- 
 mark #, i. That in our climates, it is about 
 four times as great from the vernal to the au- 
 tumnal equinox, as from the autumnal to the 
 vernal. 
 
 2dly. That other circumftances being equal, 
 it is fo much the greater, as the difference be- 
 tween the temperature of the air, and that of 
 the evaporating furface is greater ; and fo 
 much the fmaller, as this difference is fmaller, 
 and therefore fmalleit, when the air and the 
 evaporating liquid are both at the fame tempe- 
 
 * See 2 N. Com. Petrop. p. 55. 
 
 rature.
 
 Of the Sources of Heat and Cold. 1 3 
 
 rature. The former part of this proportion, 
 however, requires fome restriction ; for if air 
 be more than 1 5 degrees colder than the eva- 
 porating furface, there is fcarce any evapora- 
 tion at all ; "but, on the contrary, it depofits 
 rnoifture on the furface of the liquid. 
 
 3dly. The degree of cold produced by eva- 
 poration, is much greater when the air is 
 warmer than the evaporating furface, than 
 that which is produced when the evaporating 
 furface is the warmer of the two. For, in 
 the firft cafe, the dilatation of the vapour is 
 conftantly increafed ; and, in the fecond, it is 
 checked. Now the more vapour is dilated, the 
 more fire it abforbs ; and hence it is coldefl 
 in an exhaufted receiver where it dilates moft. 
 Hence warm winds, as the Sirocco, Harina- 
 tan, &c. are more deficcative than cold winds; 
 
 4thly. Evaporation is fo much the lefs ob- 
 ftructed by air, as the air is already lefs loaded 
 with vapour. And hence cold winds flowing 
 into warmer countries, powerfully promote it. 
 
 5thly. That it is greatly increafed by a 
 current of air or wind flowing over the eva- 
 porating furface, not only becaufe the evapora- 
 ting furface is thereby increafed ; but alfo be- 
 caufe unfaturated air is conftantly brought into 
 contact with it. Hence it has been remarked, 
 that calm days are the hotteft *. 
 
 6thly. That tracts of land covered with 
 
 * Mem. Par. 1751, p. 681, I2tno. edit. 
 
 trees
 
 14 Of the Sources of Heat and Cold. 
 
 trees or vegetables, emit more vapour than the 
 fame fpace covered with water, as Dr Hales 
 has obferved. Mr. Williams found this 
 quantity to amount to i more *. 
 
 Laftly, We may obferve, that the heat and 
 cold of different countries are tranfmitted from 
 one to the other by the medium of winds. 
 How the air of a cold country is determined 
 to flow towards a warmer, is eafily underftood ; 
 but by what means warm air is determined 
 to flow towards cold countries, is fomewhat 
 difficult to explain. I mall here mention three 
 caufes that occur to me, wiming for a fuller 
 explanation from others. 
 
 Firfl, If a ftrong northerly wind prevails 
 in the direction of the meridian oppofite to 
 London, as in the country of the Tfchutfchi^ 
 in the eaftern extremity of Afia, this current 
 muft be fupplied by air from the north pole ; 
 and this in its turn by air fouth of the pole in 
 the direction of the meridian of London. 
 
 2dly. If from any tract in the upper regions 
 cf the atmofphere, two currents of air flow in 
 oppofite directions, as fometimes happens, the 
 inferior air being lefs comprefled, will become 
 fpecifically lighter ; and currents of air in op- 
 pofite directions to the upper currents, will 
 take place. 
 
 3dly. I conceive that when eafterly and 
 wefterly winds meet with unequal force, one 
 of them may be reflected northwards. 
 
 * Second vol. Philadelph, TranfafttoHs, p. 150. 
 
 CHAP.
 
 Of a Standard Situation, 
 
 CHAP. II. 
 
 Of a Standard Situation, with whofe Tempe- 
 rature that of every other may be compared. 
 
 ROM what has been already faid, it 
 follows, that fome fituations are better" 
 fitted to receive or communicate heat than 
 other fituations ; thus high and mountainous 
 fituations being nearer to the fource of cold, 
 muft be colder than lower fituations ; and 
 countries covered with woods, as they prevent 
 the accefs of the Sun's rays to the earth, or to 
 the heaps of fnow which they may conceal > 
 and preient more numerous evaporating fur- 
 faces, muft be colder than open countries, 
 though fituated in the fame latitude; and fince 
 all tracts of land prefent infinite varieties of 
 fituation, uniform refults cannot here be ex- 
 pected. It remains then, that we feek for 
 a ftandard fituation, with whofe tempera- 
 ture in every latitude 'we may compare and 
 appreciate the temperature of all other fituations 
 in the fame latitudes, on water only. Now the 
 globe contains, properly fpeaking, but two 
 great tracts of water, or oceans; one, the At- 
 lantic feparating Europe and the weftern fide 
 of the old continent from America ; and the 
 other, the Pacific, dividing Afi a from America ; 
 both of which I divide into north and fouth, 
 
 as
 
 1 6 Of a Standard Situation. 
 
 as they* lie on the northern or fouthern fide of 
 the equator. 
 
 In this immenfe trad: of water I chofe that 
 fituation for a ftandard, which recommends 
 itfelf moft by its fimplicity and freedom from 
 any but the moft permanent caufes of altera- 
 tion, viz. that part of the Atlantic that lies 
 between the Both degree of northern and the 
 45th of fouthern latitude, and extending weft- 
 wards as far as the gulf ftream *, and to within 
 a few leagues of the coaft of America ; and all 
 that part of the Paciiic Ocean, reaching from, 
 lat. 45 N. to lat. 40 S. from the 2oth to 
 the 275th degree of longitude, eaft of London, 
 which is by far the greater part of the furface 
 of the whole globe. Within this fpace it will 
 be found that the mean annual temperature is 
 as exprefled in the following table. I have 
 added the temperature of latitudes beyond 80 
 in the northern hemifphere, though not ftrictly 
 within the ftandard. 
 
 * Dr. Blagden, in an ingenious paper in the Philofoph. 
 Tranf. for 1781, has {hewn that the temperature of this 
 ftream is confiderably greater than that of the adjacent 
 part of the Atlantic. 
 
 TABLE
 
 ( '7 ) 
 
 of the Mean Annual Temperature of 
 the Standard Situation, in every Latitude. 
 
 Lat. Temper. Lat. Temper. Lat. Temper 
 
 9 3 1 
 
 6 1 43*5 
 
 32 69,1 
 
 89 31,04 
 
 60 44,3 
 
 3i 69,9 
 
 88 31,10 
 
 59 45,09 
 
 30 70,7 
 
 8 7 31,14 
 
 58 45,8 
 
 29 71,5 
 
 86 31,2 
 
 57 46,7 
 
 28 72,3 
 
 8 5 3*>4 
 
 5 6 47,5 
 
 27 72,8 
 
 84 3i,5 
 
 55 48,4 
 
 26 73,8 
 
 83 3i,7 
 
 54 49,2 
 
 25 74,5 
 
 82 32, 
 
 53 5 ' 2 
 
 24 75>4 
 
 8l 32j2 
 
 52 51,1 
 
 23 75>9 
 
 80 32,6 
 
 5 1 5 2 >4 
 
 22 76,5 
 
 79 32,9 
 
 50 52,9 
 
 21 77,2 
 
 78 33,2 
 
 49 53,8 
 
 20 77,8 
 
 77 33,7 
 
 48 54,7 
 
 19 78,3 
 
 76 34,1 
 
 47 55,6 
 
 18 78,9 
 
 75 34,5 
 
 46 56,4 
 
 17 79>4 
 
 74 35, 
 
 45 57,5 
 
 16 79,9 
 
 73 355 
 
 44 58,4 
 
 15 80,4 
 
 72 36, 
 
 43 59>4 
 
 14 8o,S 
 
 71 36,6 
 
 42 60,3 
 
 13 -8i,3 
 
 70 37^2 
 
 41 6i,i 
 
 12 81,7 
 
 69 37,8 
 
 40 .62, 
 
 ii 82, 
 
 68 38,4 
 
 39 6 3> 
 
 10 82,3 
 
 67 39,1 
 
 38 63,9 
 
 9 82,7 
 
 66 39,7 
 
 37 6 4 ,8 
 
 8 82,9 
 
 65 40,4 
 
 36 65,7 
 
 7 83,2 
 
 64 41,2 
 
 35 66 > 6 
 
 6 83,4 
 
 63 4i,9 
 
 34 67,4 
 
 5 83,6 
 
 62 42,7 
 
 33 68,3 
 
 o 84, 
 
 This
 
 . This table is conftruded on the following 
 principles, which are neajly the fame as thofe 
 of Mayer. 
 
 Suppofmg the mean annual heat to be 
 greateft under the equator, and leaft under 
 the poles, then if the temperature of the 
 equator be m, the temperature of the north 
 pole will be m #, and putting <I> for any 
 other latitude, the temperature of that latitude 
 will be m n fin 4> a . 
 
 Now the mean annual temperature of lat. 
 40, is found by the beft obfervations, to be 
 6 2, i, and the temperature of lat. 50, is found 
 to be 52,9, and this being allowed m and 
 n, confequently the mean annual tempera- 
 tures of the equator and of the poles may 
 be determined ; for, the fquare of the fine of 
 40, is 0,41, and the fquare of the fine of 50, 
 is 0,58, both fufficiently near for the prefent 
 purpofe. 
 
 Then m 0,41 n 62,1 
 And m 0,58 n 52,9 
 Therefore 62, i -f 0,41 n = 52,9-!- 0,58 . 
 
 Whence the vSlue of n is eafily determined 
 and found to be 53 nearly, and m in the firffc 
 equation is 84 ; hence the mean temperature 
 of the equator is 84, and that of the pole 
 31, in number, 
 
 l With
 
 ( '9 ) 
 
 With refpect to the annual temperature, we 
 may remark : ift. That within 10 degrees of 
 the poles the temperatures differ very little ; 
 neither do they differ much within 10 degrees 
 of the equator. 
 
 2dly. The temperature of different years 
 differ very little near the equator, but they 
 differ more and more, as the latitudes approach 
 the poles. 
 
 3dly. It fcarce ever freezes in latitudes 
 under 35, uhlefs in very elevated fituations* 
 and it fcarce ever hails in latitudes higher 
 than 6o b *. 
 
 4thly. Between latitudes 35 and 60, in 
 places adjacent to the fea, it generally thaws 
 when the fun's altitude is 40, and feldoni 
 begins to freeze, until the fun's meridian alti- 
 tude is below 40. 
 , 
 
 * 9 Vet. Com. Ptrob. 
 
 C 2 CHAP.
 
 CHAP. III. 
 
 Of the Mean Monthly temperature of the 
 Standard. 
 
 IN every latitude, the mean temperature of 
 the month of April, feems to approach very 
 nearly, to the mean annual heat of that lati- 
 tude ; and, as far as heat depends on the action 
 of the folar rays, the mean heat of every 
 month, is as the mean altitude of the fun, or 
 rather, as the fine of the fun's altitude during 
 that month. 
 
 Hence the mean heat of April, and the 
 fines of the fun's altitude being given, I find 
 the mean heat of May, by this analogy. As 
 the fine of the fun's mean altitude in April, 
 is to the mean heat of April, fo is the fine of 
 the fun's mean altitude in May, to the mean 
 heat of May. In this manner, I find the 
 temperatures of June, July, and Auguft: but 
 this rule would give the temperatures of the 
 fucceeding months much too low ; becaufe, 
 it does not comprehend the quantity of heat 
 accruing to the atmofphere by communication 
 of the internal heat of the globe, which in 
 every latitude is nearly the fame, as the mean 
 annual heat of that latitude. Hence, the 
 real temperature of thefe months, muft be 
 
 looked
 
 looked upon as an arithmetical mean, between 
 the agronomical, and terreftrial heats. Thus, 
 in lat. 5 1 , the agronomical heat of the month 
 of September, is 44,66, and the mean annual 
 heat is52,4; therefore, the real mean heat 
 of this month, mould be 44 AIM. - ^^ 
 
 which is more conformable to obfervation. 
 
 It may indeed be faid, that not only the 
 fun's altitude in every month, but alfo the 
 duration of its light over the horizon, mould 
 be taken into confideration. And, without 
 doubt, this, and fome other circumftances taken 
 into account by Mr. De Mairan, mould not 
 have been omitted by me, if all the circum- 
 ftances productive of cold, could alfo be fub- 
 jected to calculation ; but fome of thefe can 
 no way be eftimated ; for inftance, the cold 
 produced by evaporation : therefore, by way 
 of compensation, fome of thofe productive of 
 heat, mould alfo be omitted ; and in effect, the 
 approximation of the calculated, to the real 
 heat, is much greater when this element is left 
 out. Thus the temperature of June in lat. 
 51, including this circumftance, is 70; 
 whereas, in fad:, the mean heat of June, in 
 London, is only 63, nor does it exceed 66, 
 even at Paris, lat. 48 50'. However, after 
 going through a tedious calculation, I ftill 
 found the refults to agree but ill with ob- 
 fervationj and therefore the enfuing table, is 
 C 3 not
 
 not to be looked upon as deduced from fixed 
 principles, but ratber partly from principles, 
 and partly from wbat appeared to me, after 
 iludying a variety of fea journals, moft con- 
 formable to obfervation. And, as a table of 
 the mean monthly temperatures of different 
 latitudes at fea, can never be had by obferva- 
 tion, I flatter myfelf that fuch a table as this, 
 made as correct as the nature of things will 
 allow, may in fome meafure fupply its place, 
 
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 Though the fun is one month abfent in 
 lat. 67, and two months in lat. 70, &c. yet 
 I have ventured to let the mean heat of Ja- 
 nuary, in lat. 70, no lower than 27, becaufe 
 at Wadfo, lat. 70 5' , the fea is never obferved 
 to freeze, and its temperature is generally 
 about ChriftmavS, at 32, fometimes above and 
 fometimes below it: Mem. Stock. 1753. 
 Froft, fcarce ever lies on the Orkneys, lat. 
 59 ; and that excellent meteorologift, Mr. 
 Reyer, relates, that at Archangel^ lat. 64, in 
 October, a foutherly wind is much colder 
 than a northerly. He alfo obferved, that in 
 Dantzick^ lat. 54, even in the month of Ja- 
 nuary, a north wind brings on a thaw, or at 
 leaft moderates the froft, whereas a fouthedyr 
 wind is intenfely cold* : which fhews, that 
 the north Atlantic is notfo cold as is generally 
 imagined; for the Baltic is certainly colder in 
 Winter, than the Atlantic in the fame latitude. 
 From this table we may learn, 
 
 i ft. To find the mean heat of the iirft, and 
 laft half of any month. 
 
 Find the mean betwixt the ftandard heat of 
 any month, and the ftandard' heat of the luc- 
 ceeding; this will be the mean of the laft 15 
 days of the preceding, and the firft 14 or 15 
 days of the fucceeding month. 
 
 2dly. To find the ufual extremes whether of 
 heat, or- of cold, that take place in any month. 
 
 * 2 Abhaudlung. in Dantzic, p. 143; 
 
 Find
 
 Find the difference of the monthly and 
 annual temperatures ; this difference added to 
 the monthly temperature, gives the temperature 
 of the hotteft day, that is ufually found in any 
 month ; or being fubtrafted gives the coldeft 
 day, ufually obferved within the month : by 
 day, I mean the fpace of 24 hours. Thus in 
 London, the annual temperature being 52, 
 and the temperature of Jan. 36, the difference 
 is 1 6, confequently the warmeft day in Ja- 
 nuary is 52, and the coldeft 20. 
 
 The greateft cold within the 24 hours, ge- 
 nerally happens \ an hour before funrife, in 
 all latitudes. The greateft heat in all latitudes 
 between 60 and 45, is found about f paft 
 2 o'clock in the afternoon ; between lat. 45 
 and 35, at 2 o'clock; between- lat. 35 and 
 25, at | paft ; one and between lat. 25, and 
 the equator, at I o'clock. 
 
 On fea, the difference between the heat of 
 day and night, is not fo great as on land, par- 
 ticularly in low latitudes. 
 
 The coldeft weather in all climates, generally 
 prevails about the middle of January, and the 
 warmeft in July, though, aftronomically fpeak- 
 ing, the greateft cold mould be felt at the 
 latter end of December, and the greateft heat 
 in the latter end of June ; but the earth requires 
 fome time to take, or to lofe the influence 
 of the fun, in the fame manner as the fea 
 with refpeci to tides, does that of the moon. 
 
 CHAP, 
 

 
 Of the Difference of Temperature, &c. 29 
 
 CHAP. IV. 
 
 Of the Difference of ^Temperature of 'Air , Land, 
 and Water ; and of their Capacities of receiv^ 
 ing, and tranfmitting Heat. 
 
 A I R, when perfectly clear and tranfpa- 
 rent, receives very little heat from light, 
 as has been already faid ; but, if cloudy, it 
 is capable of receiving much more, and hence 
 cloudy air is often warmer than the earth 
 over which it is incumbent. Air, is alfo often 
 warmed, by the condenfation of the vapours 
 interfperfed through it, particularly when this 
 condenfation arifes from electrical agency, and 
 by thefe means the upper ftrata of the at- 
 mofphere, are often warmer than' thofe which 
 are fomewhat lower ; and hence, the origin 
 of hail, which is rain condenfed by paffing 
 through air colder than that in which it was 
 produced; but the greater part of the heat of 
 the atmofphere, is certainly derived from its 
 communication with the land, or water, over 
 which it (lands, and in this way it receives, 
 either heat, or cold, more readily than any other 
 body of the fame bulk, particularly if it be 
 confined, as in vallies ; but it conduces thefe 
 qualities to or from other bodies, very llowly, 
 as the points of mutual corftact, a/e inconfider- 
 
 able.
 
 30 Of the Difference of Temperature^ &c. 
 
 able. Snow, falling from the higher regions 
 of the atmofphere, is generally colder than the 
 lower air; which, therefore, after a fall of 
 fnow, is often colder, than air 30 or 40 feet 
 above the furface, as appears from the expe- 
 riments related by Mr. Wilibn in the Philofo- 
 phical Tranfa&ions of the year 1780. 
 
 Air, incumbent on feas, or on large traces of 
 water, is generally many degrees warmer in 
 Winter, and cooler in Summer, than air in- 
 cumbent on land, becaufe land is more fufcep- 
 tible of both heat and cold, than water; and, in 
 general, air participates of the temperature of 
 the fubitances with which it is in contact. 
 
 The capacities of land and water for re- 
 ceiving heat, or cold, are very different* 
 Land^ or earth, particularly if dry, receives heat 
 from light very readily, but transmits, or con- 
 ducts it through its own fubftance, to great 
 depths, very flowlyj whereas water, by reafon 
 of its traniparency, receives heat from light 
 very ilowly, but what it receives, is diffufed 
 through it much more readily. Dr. Hales 
 found that in the month of Auguft, 1724, 
 when the air and the furface of the earth were 
 both at 88, a thermometer placed only 2 
 inches under the furface, ftood at 85 ; and 
 another 1 6 inches under the furface, indicated 
 70 ; and another 24 inches deep, 68. Thefe 
 two laft mentioned thermometers, preferved 
 the fame temperature both day, and night, 
 until tjie end of the month, and then fell only 
 
 to
 
 Of the Difference of temperature^ &c. 31 
 
 to 63 or 61; fo obftinately did the earth, at 
 that depth, retain its heat, though the tempera- 
 ture of the air frequently varied*. 
 
 On the 26th of O&ober, a thermometer ex- 
 pofed to the air, flood at 35,5 ; but one funk 2 
 inchesin the earth,was heated to 43, 85; another 
 funk 1 6 inches, mewed 48, 8; and one at the 
 depth of 24 inches, 50; he even found, that 
 between the ift and I2th of November, when 
 the external air was cooled fo low as 27, an- 
 other thermometer placed at the depth of 24 
 inches, flood at 43, 8; but from the month 
 of March, to that of September, of the 
 following year, the external air was con- 
 flantly warmer, than the earth at the depth of 
 1 6 inches, or 2 feet; but the feafon was very 
 rainy, and the evaporation occafioned thereby, 
 prevented the earth from being warmed, fo 
 much as it otherwife would have been. How- 
 ever, thefe experiments clearly prove, ift. 
 That the furface of the earth is much heated 
 during the Summer, but that this heat defcends 
 very flowly, a great part of it being commu- 
 nicated to the air. 2dly* That during the 
 Winter, the earth gives out to the air, the heat 
 it had received during the Summer. 3dly. 
 That wet Summers, muft be fucceeded by cold 
 Winters. 
 
 Thefe experiments agree very well with 
 thpfe of Mariotte, who found, that the earth 
 
 t 
 
 * i $ales Veg. Stat. p< 61, 
 
 is
 
 32 Of the Difference of Temperature, &c. 
 
 is gradually heated during the Summer, and 
 as gradually cooled during the Winter months, 
 and that, at the diftance of a few feet under the; 
 furface, it is conftantly wanner than the ex- 
 ternal air ; this excefs he found to remain 
 until April, when the furface is again heated 
 by the fun's rays, and ilowly tranfmits its 
 heat downwards. In all this, we fee nothing 
 like the operation of a central heat. * 
 
 Hence at a certain diftance from the furface, 
 namely, about 80 or 90 feet, (if this depth has 
 any communication with the open air, and 
 perhaps, at a much lefs depth, if there be no' 
 fuch communication) the temperature of the 
 earth varies very little, and generally ap- 
 proaches to the mean annual heat. Thus the 
 temperature of fprings, is nearly the fame as 
 the annual temperature, and varies very little 
 in the different periods of the year, as Mr. 
 Hellant has firft obferved. Thus alfo the 
 temperature of the cave of the obfervatory at 
 Paris, about 90 feet below the pavement, is 
 about 53,5 degrees, and varies about I a de- 
 gree in very cold years. Its temperature is 
 fomewhat above the mean temperature of 
 Paris, on account of its communication with 
 the external air. Mr. Van Swinden has ob- 
 ferved that the greateft cold, even that which 
 exceeds o of Fahrenheit, if it lafts only a few 
 days, penetrates no deeper than 20 inches^ 
 
 * Mariotte fur le Froid & le Chaud, p. 189. 
 
 even
 
 Of the Difference of temperature, &?. 33 
 
 even, when the earth is not covered with mow, 
 and not above I o inches where fnow lies on 
 the furface; by which we learn the important 
 purpofes this covering anfwers in high northern 
 latitudes. In Siberia, where the cold is known to 
 be fo intenfe, immediately after the melting of 
 the fnow, the earth is found unfrozen, not only 
 at its furface, but even to the depth of 16 
 feet, which mews that ice never penetrates 
 into it, except in a very few places. By an 
 obfervation made at the bottom of a mine 
 lying between Calais and Boulogne, 476 feet 
 beneath the furface, the temperature was 54 ** 
 The temperature of the fait mines at Wic- 
 liczka, in Poland, is 52 at the depth of 320 
 feet; and from thence to the depth of 716 
 feet, it does not vary f , though the tempe- 
 rature of mines is fubjecl: to changes from 
 caufes that are peculiar to them : thus Mr. De 
 Luc, at the depth of 801 feet in the mine of 
 St. John in the Hartz, experienced a heat of 
 70 ; but at the depth of 1359 feet, he found 
 it no greater than 50 J. Kraft obferved the 
 temperature of a cavern near Reutling, in Sua-^ 
 bia, to be 48, but water in the fame cavern, 
 was heated only to 42, the external air at that 
 time being at 66 || . The mine of Joachimftahd 
 inBohemia, is reputed one of the deepeft exifting ; 
 
 * 3 Aft. Helvet. p. 27. f Guettard Mem. Par. 1762, 
 p. 1087 and 1089, 8vo. Edit, % Phil. Tranf, 1779, P- 5 02 - 
 )| Mem. Petrob. 144. 
 
 D in
 
 34 Of the Difference of Temperature, &c. 
 
 in this, Mr* Monnet found the temperature, at 
 the depth of 1700 feet, to be 50*. 
 
 All thefe fads, tend to prove that the heat 
 of the earth does not increafe as we defcend 
 into it, hut at the greateft depths, is nearly the 
 fame, as the mean annual temperature of the 
 latitude. When the furface of the earth is 
 cooled rapidly, the interior parts are cooled 
 proportionably, to a certain depth, until the 
 cold of the furface arrives at its maximum, and 
 becomes conftant ; then the internal heat gra- 
 dually gains upon it, with a force proportioned 
 to their difference of temperature; and as in 
 our climates, the internal heat is always above 
 40, it is always fufficient to melt the fnow 
 that lies long on the furface. Hence in SwifTer- 
 land, and many other countries, fnow is ob- 
 ferved to melt nrft at the bottom. 
 
 Land, is capable of receiving much more 
 either heat, or cold, than water. In the neigh- 
 bourhood of Marfeilles, Dr. Raymond found 
 land often heated to 160; but he never found, 
 the fea hotter than 77, and even this heat it 
 receives chiefly by communication with land; 
 for, on the igth of July 1765, he found that 
 part of the bay next the land heated to 74, 
 the middle of the bay being at 72, and the 
 entrance of the bay 70. In Winter he fre- 
 quently bbferved, the earth cooled down to 
 14 or 15, but the fea never lower than 44, 
 
 * 10, Roz. 234. 
 
 or
 
 Of the Difference of Temperature, &ct 3 ^ 
 
 or 45; * and the reafon is, not only, becaufe 
 water is incapable of receiving much heat from 
 light, as already faid, but becaufe it is con- 
 ilantly cooled by evaporation. In Winter, 
 when the furface is much cooled by contact 
 with colder air, the deeper and warmer water 
 of the bottom, being fpecilically lighter, riles 
 and tempers it ; and as the colder water con- 
 ftantly defcends during the Winter, hence it is, 
 that in the fucceeding Summer, the furface is 
 generally warmer than at greater depths, 
 whereas in Winter, it is colder ; hence alfo it 
 has been remarked, that after a ftorm, the 
 fea is always warmer in Winter, and colder in 
 Summer, the water of great depths being then 
 mixed and incorporated with that of the 
 furface f . 
 
 Heat at the Depth. 
 N. Lat. Surface. Feet. Heat. 
 
 68 
 65 
 
 53 
 
 * Mem. tie la Societe deMed. de Paris, An. 1778, p. 70. 
 t Suenflc. Handling. 1753. Phil. Tr. 1770. p. 39. 
 2 Bergm. Erde Kugel, p. 119. || Phil. Tr. 1752. 
 P. 213. 
 
 D 2 But 
 
 May 
 
 12 
 
 3 6 : 
 
 502 
 
 39 
 
 
 J 7 
 
 37 
 
 54 
 
 39 
 
 June 
 
 9 
 
 44 
 
 553 
 
 40 
 
 Jiy 
 
 7 
 
 46 
 
 420 
 
 44 
 
 
 8 
 
 47 
 
 1560 
 
 5 2 
 
 
 9 
 
 4* 
 
 1280 
 
 48 
 
 
 10 
 
 52 
 
 846 
 
 45 t 
 
 Jan. 
 
 3 
 
 64 
 
 54 
 
 58
 
 36 Of the Difference of temperature^ &c. 
 
 But Lord Mulgrave found the temperature 
 of the fea, at great depths, in high latitudes, 
 much colder ; he does not indeed mention, the 
 temperature of the furface, but it is prefumed, 
 it did not differ much from that of the air ; 
 perhaps the reafon was, that the newly melted 
 ice, had then deicended, though the firft expe- 
 riment cannot be explained, even on that 
 hypothefis. 
 
 Lat. N. Heat of Air. Depth. Hoat of the Sea. 
 
 67 June 20 48^5 4680 26 
 78 30 4o,5 708 31 
 
 69 Aug. 31 59,5 4038 32 
 
 Obfervations of Meflrs. Wales and Bayley. 
 
 Depth. Heat of the 
 
 Lat. 
 
 Air. 
 
 Surface. 
 
 Feet. 
 
 Sea. 
 
 o Sept. 5 
 
 75,5 
 
 74 
 
 5 10 
 
 66 
 
 24 S. 26 
 
 7^5 
 
 7 
 
 480 
 
 7 
 
 3444'0a. ii 
 
 6o', 5 
 
 59 
 
 600 
 
 57 
 
 Obfervations of Mr. Bladh . * 
 
 57 N. 
 
 Jan. 8 
 
 46 
 
 37 
 
 6 
 
 40* 
 
 
 10 
 
 
 
 50 
 
 43 6 
 
 55-40 
 
 20 
 
 47 
 
 40 
 
 no 
 
 51,5 
 
 39.30 
 
 28 
 
 53 
 
 59 
 
 no 
 
 59 
 
 2-55 
 
 Feb. 25 
 
 81 
 
 81 
 
 58 
 
 81 
 
 2.50 
 
 26 
 
 83 
 
 84,5 
 
 IIO 
 
 81 
 
 * Suenlk. Handling. 1781. 
 
 Mr.
 
 Of the Difference of ^Temperature, tSc. 37 
 
 Mr. De Sauffure, in the month of Auguft, 
 found the temperature of the lake of Geneva, 
 at the depth of 87 feet, to be about 55 of 
 Fahr. while at the furface it was 62, the heat 
 of the air being 8 1. In Winter, the tempera- 
 tures of the furface and bottom, are nearer to 
 an equality ; thus in the month of February, 
 after a froft that had lafted a month, the air 
 being at 38, the furface of the lake was at 
 41, and at the depth of looofeet, the tem- 
 perature was 40, probably from a mixture of 
 fnow water. 
 
 As the water in the high northern and fouth- 
 ern latitudes, is, by cold, rendered fpecifically 
 heavier than that in the lower warm latitudes, 
 hence there arifes a perpetual current from the 
 poles to the equator, which fometimes carry 
 down large mafles of ice, which cool the air, 
 to a great extent. It is certain that inland 
 feas, of great extent, have been frozen in very 
 levere Winters ; thus the Baltic was fo firmly 
 frozen in 1668, that Charles the Xlth of 
 Sweden and his whole army pafled over it *, 
 and the Adriatic was frozen in 1709 f. 
 Hence, there is great reafon to think, that 
 within lat. 80. N. and in much lower lati- 
 tudes in the S. hemifphere, the fea is al- 
 ways frozen in winter. Upon the whole, the 
 temperatures of land and water, in Winter, di- 
 
 * Pnffend. Hift. Europe. Mod. Un. Hift. in 8vo. Vol. 30, 
 p. j 80. f Mem Par. 1749. 
 
 D 3 fer
 
 38 Of the Difference of Temperature, &c. 
 
 fer much more than in Summer, for in Winter, 
 inland countries, from lat. 49 to 70 degrees, 
 are frequently cooled down to 40, 50, and 
 fome to upwards of 70 below the freezing 
 point ; whereas the fea below lat. 76 feems no 
 where cooled below 4 under that point in our 
 northern hemifphere, except fome narrow feas 
 and fome parts of the north Pacific Ocean ; but 
 in Summer no confiderable extent of land is 
 heated to more than 15 or 20 degrees above 
 the temperature of the fea, ftony and fandy 
 defarts excepted. All bodies require a certain 
 quantity of elementary fire or light to heat 
 them to a certain degree, but the quantity re- 
 quifite to produce this degree varies, according 
 to the nature and fpecies of thefe bodies, and 
 hence the proportion fuited to each, is called 
 their fpectfic fire ; the more of this any fpecies 
 of bodies requires, the greater time it will 
 require, in the fame circumftances, either to 
 acquire or to lofe it, that is, either to heat or 
 to cool. Now water requires much more of 
 it than earth, and therefore is longer either in 
 heating or cooling ; and therefore if the times 
 of expofure to the caufes either of heat or of 
 cold be the fame, land will take more and 
 water lefs of either of them ; hence ice is firft 
 formed near the banks of rivers, or on the 
 coafts of the fea, where the fea is frozen. 
 
 Stones or fand contain lefs fpecific fire than 
 earth, this being always moifter, hence they 
 heat and cool more readily, and to a greater 
 
 degree,
 
 Of 'the Difference of ' Temperature, &c. 39 
 
 degree, which accounts for the violent heats 
 of the defarts of Arabia and Africa, and the no 
 lefs intenfe cold of Terra del Fuego, and other 
 ilony countries in cold latitudes. It is faid 
 that caverns in gypfeous mountains are colder 
 than thole in calcareous mountains *. Towns 
 being formed of flone, or brick, are warmer in 
 Summer than the open country, unlefs the 
 ftreets be fo cloie as to intercept the free action 
 of the fun's rays. 
 
 Living Vegetables alter their temperature very 
 flowly and difficultly, but the evaporation from 
 their numerous furfaces, is much greater, than 
 from the fame fpace of land uncovered with 
 vegetables ; if they are tall, and clofe as forefts, 
 they prevent the fun's rays from reaching to, 
 and wanning the earth, befides protecting the 
 Winter's fnow for feveral months. Hence 
 wooded countries are much colder than thofe 
 that are open and cultivated ; the difference is 
 no where fo ftrongly marked as in Guyana ; 
 part of this country has been cleared from 
 wood, only fince the beginning of this century, 
 and the heat in that part is already exceffive ; 
 whereas in the wooded parts, the inhabitants 
 are obliged to light a fire every night f , which 
 mews that the earth retains very little heat. 
 When dry, cold winds, fuch as thofe that blow 
 over mountains, or dry, barren lands, pafs over 
 
 * 4 Decouvertes Ruffes, p. 34. t 9 Buffon. Suppl. in 
 8vo. p. 346. 
 
 D 4 forefts,
 
 40 Of the Modifications of tie 
 
 forefts, by exciting a more copious evapora-i 
 tion, they cool them, and are themfelves cooled 
 by them, to a far greater degree than where 
 that circumftance does not occur, and hence 
 the fouthern countries of Europe are far 
 warmer now, than they were 1 700 years ago ; 
 for though Italy, for inftance, might have been 
 as well cultivated then as at prefent, yet, as Dr. 
 Williamfon well remarked, Germany was 
 covered with woods, and confequently the 
 winds that patted from it to Italy were far 
 colder *. Abftracling from the circumftances 
 to be mentioned in the next chapter, land 
 takes 8 or 10 degrees more heat than the fea 
 in Summer, and is 8 or 10 degrees colder in 
 Winter, in the fame latitude. 
 
 CHAP. V. 
 
 Of the Modifications of the Standard 'Temper a-* 
 ture y on Land, arlfmgfrom Situation. 
 
 VT /E have already feen that the higher re- 
 gions of the atmofphere are the coldeft ; 
 that land is colder in Winter, and warmer in 
 Summer than water ; and that with refpecl: to 
 temperature, the covering of the furface of 
 land, whether with vegetables, or with ftone 
 pr fand, is not indifferent ; from whence it 
 
 * Mem. Philad, 
 
 naturally
 
 Standard 'Temperature, fcfr. 41 
 
 naturally follows, that the circumftances that 
 govern the temperature of land are, I ft. Eleva- 
 tion. 2dly. Vicinity to, or diftance from, large 
 tracts of water, particularly from the ftandard 
 ocean, as its influence is moft extenfive, and 
 as it is to its temperature that the temperature 
 of all countries is to be referred, in moft cafes. 
 3dly. The vicinity, or diftance of other tracts 
 of land, which by their elevation or the cir- 
 cumftances of their furface, have a tempera- 
 ture peculiar to them, as ftony, fandy, and 
 wooded countries. 4thly. The bearing of 
 neighbouring feas, mountains, forefts, de- 
 farts, &c. 5thly. A more or lefs perfect 
 communication with the ftandard ocean, feas, 
 &c. 
 
 Of Elevation. 
 
 A S heat is propagated through the atmo- 
 fphere, chiefly by contact and communication 
 with the earth, it is evident that lofty moun- 
 tains, particularly if their horizontal furface 
 be not very extenfive, cannot warm it to any 
 considerable degree, as they themfelves re- 
 ceiving the fun's meridian rays more obliquely, 
 and communicating lefs with the common 
 mafs of the earth, are lefs heated than plains, 
 hence the fteepeft mountains are always the 
 Cpldeft; but elevated countries of large ex-
 
 42 Of the Modifications of the 
 
 tent, fuch as the interior parts of continents, 
 and iflands whofe declivity is infenfible, parti- 
 cipate much lefs of this diminution of tempe- 
 rature ; yet that part of the atmofphere which 
 is in contact even with the loftieft mountains, 
 is wanner, at leaft in Winter, than air of the 
 fame height over plains, becaufe fuch im- 
 menfe maffes of earth, and ftone, generally 
 contain more heat than mere air, and the air 
 in contact with them, being on that account 
 fpeciiically lighter than the more diftant air, 
 this of courfe moves towards the mountains, 
 or the general current of the atmofphere flows 
 towards them with greater velocity, and hence 
 clouds feem to be attracted by them, and 
 winds are generally more violent on high 
 mountains than on plains *. The air thus ac- 
 cumulated on their fides, is at length forced 
 over their fummits, but in afcending to a 
 greater height than that, at which it was im- 
 pregnated with vapour, it is cooled and confe- 
 cjuently depofits this vapour, which thus forms 
 mifts on the fides of the mountain, and when 
 the quantity of vapour thus condenfed is confi- 
 derable, it warms the air to a confiderable de- 
 gree t. On the other hand, the air forced over 
 the mountain, being deprived of its vapour, and 
 falling on the neighbouring plains, greedily 
 abforbs the moifture it had loft, and thus pro- 
 
 * De Luc. f See a full and excellent account of thefe 
 phenomena, by Mr. Du Carla, 21 Roz. and the fuc- 
 ceeding volumes. 
 
 duces
 
 Standard temperature^ &c. 43 
 
 duces a confiderable degree of cold. Thus a 
 N. \V. wind blowing on the mountains of 
 Norway occafions a thaw, but when it has 
 panned thefe mountains and entered Sweden, 
 it produces the moil intenfe cold *; and for 
 the fame reafon, this wind is obferved to be 
 the drieil and coldeft on the eaftern coaft of 
 Scotland, and the heavieil rains come from 
 theEaft andS.E.f. 
 
 With refpect to the precife effect of eleva- 
 tion, I find it to be very nearly as follows. 
 
 i ft. When the elevation is moderate and 
 gradual, fuch as that of the interior parts of 
 moil countries very diftant from the fea, its ef- 
 feds are fo blended with thofe of diilance ff orn 
 the ilandard ocean, to be mentioned in the 
 next feclion, that the fame allowance in the 
 diminution of temperature, is to be made for 
 both. By a gradual elevation, I mean any 
 that rifes at a lefs rate than fix feet per mile, 
 counting from the nearefl confiderable fea. 
 
 2dly. If the elevation proceeds at a greater 
 rate, then for every 200 feet of elevation, we 
 muft diminifh the annual temperature of the 
 ilandard in that latitude, as follows. 
 
 If the elevation be at the rate of 
 
 6 feet per mile i of a degree. 
 
 7 feet - - f 
 
 4 
 
 I 3 feet 
 
 15 or upwards - i: 
 
 * Mem. Stock. 1757. t 3 Ed. Eilliys, p. 12. 
 
 To
 
 44 Of the Modifications of the 
 
 To find the height of any place, I com- 
 pare the mean annual height of the barometer 
 at that place, at its mean annual temperature, 
 with its mean height at the level of the neareft 
 fea at the mean annual temperature of that 
 fea, which height I fuppofe to be 30 inches. 
 Sir George Schuckburgh found it fo in the 
 Mediterranean and channel, in the tempera- 
 ture of 55 and 60. Mr. Bouguer found it 
 fo on the coaft of Peru, in the temperature of 
 84; and Lord Mulgrave obferved it at the 
 fame height in lat. 80 : and though fome feas 
 are faid to be higher than others, yet this ine- 
 quality is never fo great as to occafion any 
 important difference in the height of the baro- 
 meter. 
 
 2. 
 
 Diftance from the Standard Ocean. 
 
 FROM the frequentlhtercourfe of land and 
 fea winds, the annual temperature of countries 
 bordering on the ocean, differs very little from 
 that of the ftandard in the fame latitude, un- 
 lefs their elevation, or fome of the circum- 
 flances already mentioned occafion a differ- 
 ence ; for though they are fomewhat warmer 
 in Summer and colder in Winter, yet upon 
 the whole within the year, thefe differences 
 nearly balance each other in the temperate lati- 
 tudes ; but at the diftance of 50 miles from 
 
 the
 
 Standard Temperature, cj?c. 45 
 
 the fea, and ftill more at greater diftances, the 
 differences arifing from the unequal capacities 
 of land and water are fenfibly perceived, the 
 mean annual temperature in different latitudes 
 being depreffed or raifed in every 50 miles dif- 
 tance, nearly at the following rate : 
 
 From lat. 70 to lat. 35 cooled f of a degree. 
 
 35 * 
 
 30 - - 
 
 25 warmed 
 
 20 i 
 
 10 
 
 o 
 
 I 
 
 It appears then, that from lat. 70 to lat. 
 30, elevation, and diftance, confpire in pro- 
 ducing the fame effect, that is, in lowering the 
 annual temperature ; hence one would fup- 
 pofe, that their joint effect mould be the pro- 
 duct of both powers; but as the effect of eleva- 
 tion is in fome meafure complicated with that 
 diftance, namely, when the elevation is lefs 
 than 6 feet per mile, I find it more agreeable 
 to obfervation, to add the effects of diftance 
 and elevation to each other. In latitudes be- 
 low 30*, elevation and diftance from the 
 ilandard ocean, in general counteract each 
 other, and therefore the effect of one, is to 
 be fubtrafted from that of the other. 
 
 3- Of
 
 46 Of the Modifications, &c. 
 
 '> 
 
 Of the Modifications produced by the Vicinity and 
 Bearings of Mountains, Seas, tsc. 
 
 ALL countrieslyingto the windward of high 
 mountains, or extenfive forefts, are warmer than 
 thofe lying to the leeward, in the fame latitude. 
 
 Countries that lie fouthward of any fea, are 
 wanner than thofe that have that fea to the 
 fouth of thero, at leaft in our hemifphere, be- 
 caufe the winds thatfnould cool them in Winter 
 are tempered by paffing to them from that fea ; 
 whereas thofe that are northward of the fea 
 are cooled in Summer by the breezes that ifllie 
 from it ; but a northern or fouthern bearing 
 of the fea, renders a country warmer, than if 
 it lay either to the eaft, or to the weft. 
 
 Ijlands being furrdunde'd by the fea, parti- 
 cipate more of its temperature, and are there- 
 fore warmer than continents ; moll great 
 iflands have, (which is very remarkable) their 
 greateft extent, from north to fouth, as Great 
 Britain, Ireland, Madagafcar, Ceylan, For- 
 mofa, Sumatra, &c. yet in our hemifphere, 
 the fouthern parts, are proportionably colder 
 than the northern, became the northerly 
 winds in Winter are cooled, by blowing over 
 a large extent of land *. A ridge of moun- 
 tains generally traverfes them in the direction 
 of their length. 
 
 * Hence Pallas was much miftaken in imagining, that 
 England would be much colder, if it were not flickered 
 from the northerly winds, by the mountains of Scotland. 
 
 4 CHAP.
 
 Of the temperature^ &c. 47 
 
 CHAP. VL 
 
 Of the temperature of the North Pacific 
 from Lat. 66 to 52*. 
 
 THIS part of the Pacific Ocean, is con- 
 tra&ed in lat. 66 to the narrow fpace 
 of 40 miles, and in lat. 52 it occupies the 
 fpace of only 30 in breadth, from, eaftj'to 
 weft, that is about 1300 miles*; whereas the 
 Atlantic in lat. 52 is about 1700 miles in 
 breadth, and is no where contracted to a lefs 
 fpace than 700 miles. Add to this, that the 
 coaft of Alia on the one fide, and thofe of 
 America on the other, are bordered with high 
 mountains covered with fnow for a great part 
 of the year ; and numerous high illands lie 
 fcattered between both- continents. From thefe 
 circumftances we have fufficient reafon to con- 
 clude a priori^ that this fea mould be much 
 colder than that portion of the Atlantic, con- 
 tained between the fame parallels; for, during 
 the Winter, the mountains that line the coafts, 
 are cooled to a much greater degree, than the 
 flat coafts of the Atlantic; and the fea, where 
 
 * The degrees of longitude are computed from a table 
 in Mr. De La Lande's Aftronomy. Toifes divided by 825, 
 give Engjifh miles, very nearly. 
 
 narrow,
 
 48 Of the Temperature ', &c. 
 
 narrow, is intirely frozen ; in Summer, heaps 
 of ice being long flickered from the fun by 
 the illands, are carried down into lower lati- 
 tudes, and the fnow remains long unmelted 
 on the mountains ; fo that I am inclined to 
 think, that the annual temperature of it, is at 
 leaft, 4 degrees below that of the ftandard in 
 each corresponding latitude. But the obfer- 
 vations eitheron thefe feas, or the neighbouring 
 coafts, are not as yet fufficiently numerous, to 
 determine with any precifion, the mean 
 annual temperature of thefe parts. The 
 few particulars here mentioned, are chiefly 
 collected from the account of Captain Cook's 
 laft Voyage ; but the zeal of that beft and 
 greateft of Sovereigns, the prefent Emprefs of 
 Ruffia, whofe love of fcience, and of every 
 improvement that can contribute to the hap- 
 pinefs of mankind, can only be compared with 
 the extent of her empire, will not, it is to be 
 expected, long fuffer the meteorological hiftory 
 of fo confiderable a part of the globe to remain 
 unknown. 
 
 CHAP.
 
 Of the Temperature, &c. 49 
 
 CHAP. VII. 
 
 Of the Temperature of the Ea/lern Part of North 
 America. 
 
 t A HERE are many cifcumflances that 
 A contribute to render thefe parts colder 
 than the oppofite parts of the old continent. 
 Firft, The higheft lands in North Ame- 
 rica are contained between the 4Oth and jfoth 
 degrees of latitude, extending from north to 
 fouth between the tooth and noth degrees 
 of longitude weft of London ; here the great- 
 eft rivers have their fource. To the eaft of 
 thefe lie the Lakes Superior, Michegan, Huron, 
 Ofwego, &c. and the intermediate country is 
 covered with impenetrable forefts; hence, this 
 vaft fpace is incapable of receiving much heat 
 in Summer, and confequently one great fource 
 of that warmth, by which the Winters in the old 
 continent are moderated, is here confiderably 
 diminifhed ; add to this, the fwamps and mo- 
 rafles, which are equally incapable of receiving 
 any confiderable heat ; hence, the wefterly 
 winds, at leaft fuch of them as originate be- 
 hind thefe high lands, having depofited their 
 vapours in pafling over them, re-abforb them 
 from thefe immenfe forefts and numerous 
 E lakes,
 
 50 Of the Temperature^ &, 
 
 lakes, and thereby are cooled ftill more. Farther 
 north, namely, between lat. 52* and 63, lie 
 Hudfon's Bay and Streights ; about 50 miles 
 on the fouth of this Bay, from lat. 50* to 58, 
 there runs a ridge of mountains, which pre- 
 vents its receiving any heat from that quarter, 
 and hence the intermediate country is fo cold 
 th.at fcarce any animal can live in it * . To the 
 eaft, this bay is bounded by the barren, moun- 
 tainous country of Labrador, and a number 
 of iflands that lie at its entrance. The portion 
 of the Atlantic oppofite to the entrance of the 
 Streights, is furrounded, partly by the continent 
 of America, and partly by Greenland, as far 
 down as lat. 59 ; both are mountainous and 
 interfected by a multitude of creeks and inlets, 
 which are frozen over in Winter, and in the 
 enfuing Summer the floating ice is protected 
 by numerous high iflands, and partly carried 
 down the eaftern coaft of America, fometimes 
 as far as latitude 42 f, cooling the atmo- 
 fphere far below the ftandard. 
 
 Hence, the N. W. winds are the coldeft in 
 all thefe parts of America, and by the meteo- 
 rological journals that have been publiihed, 
 the annual temperature feems to be about 10 
 or 1 2 degrees lower than the ftandard. 
 
 But, as the cultivated parts of America are 
 at prefent much more temperate than they 
 were a century ago; it may be prefumed, that 
 
 * Carver's Travels, p. jo8. t Hift. Accad. Par. 1725. 
 
 wheu
 
 Of the 'Temperature , &c. 5 1 
 
 when the country is ftill further cleared of 
 woods, the climate will be ftill further im- 
 proved, though, from the fituation of the 
 high lands, I believe it will never be fo mo- 
 derate as that of Europe. 
 
 CHAP. VIII. 
 
 Of the 'Temperature of the Southern Hemifphere* 
 
 FROM the equator to latitude 40% the 
 temperature of this hemifphere feems to 
 be exactly the fame as that of the correfpond- 
 ing parallels on the northern fide* : but it 
 is the general opinion, that the more fouth-* 
 6rn latitudes are much colder than the north- 
 ern, equally diftant from the equator. If this 
 opinion refpected only the Summer feafon, or 
 latitudes higher than 6o d , there is good reafon 
 to think it well founded ; for, in this hemi- 
 fphere fo low as lat. 68, the fea has been found, 
 by that incomparable navigator Captain Cook, 
 every where frozen; and large mafles of ice 
 are in Summer detached and carried down as 
 low as lat. 50, or even 46, and there, melting, 
 diffufe cold to a far greater extent : but on the 
 
 * i Gentil. Voy. p. 73, 
 
 E 2 other
 
 52 Of the Temperature of the Lejjer Seas. 
 
 other hand, the abfence of land, which it 
 known to receive a far greater degree of cold 
 than water, makes it highly probable, that 
 the antarctic Winters are much milder than the 
 arctic, at leaft on land. 
 
 It is worthy of obfervation, that Dr. Halley 
 and Mr. Wales have fometimes found the 
 northern wind colder than the fouthern, in 
 this hemifphere*. 
 
 CHAR IX. 
 
 Of the Temperature of the Lejjer Seas. 
 
 TN general thefe feas, if not furrounded by 
 * high mountains, are a few degrees warmer 
 in Summer, though colder in Winter, than the 
 ftandard ocean ; in high latitudes they are 
 frequently frozen. 
 
 White Sea. 
 This fea is frozen in Winter f 
 
 Gulph of Bothnia. 
 
 It is in great meafure frozen in Winter J, 
 but in Summer it is fometimes heated to 70% 
 
 * Dalrymple's Voy. p. 37, and Wales's Obfervation* 
 en his Voyage. \ 2 Dantzic Abhandl. p. 143. 
 
 J Mem. Stock, 1757. 
 
 ade-
 
 ^ Of the 'Temperature of the Lefler Seas. 53 
 
 & degree of heat never to be found in the 
 oppofite part of the Atlantic * ; its general 
 temperature in July is from 48 to 56. 
 
 German Sea. 
 
 This fea feems to be about 3 degrees colder 
 in Winter, and 5 degrees warmer in Summer, 
 than the Atlantic; hence, though colder in 
 Winter, yet it is as warm in Summer at 
 Southwic, lat. 52 3i'||, as at Briftol, lat. 51* 
 33' : the annual temperature is even lower 
 at Briftol than at London ; thus in 1 778, the 
 temperature of London was 53,1, but that of 
 Briftol was only 52. 
 
 ,Mediterranean. 
 
 This fea is for the greater part of its extent, 
 warmer, both Summer and Winter, than the 
 Atlantic, which for that reafon flows into it ; 
 but the Adriatic, though warmer in Summer, 
 is fo cold in Winter, as to have been frequently 
 frozen over in the neighbourhood of Venice. 
 
 Black Sea, 
 
 Is colder than the Mediterranean, and 
 flows into it, 
 
 Cafpian. 
 This fea is fituated in the neighbourhood 
 
 * Mem. Stock. 1776. || 8 Phil. Tranf. Abr. p. 610. 
 J; Mem. Par. 1749. 
 
 E 3 f
 
 54 Of the temperature of Places ^ 
 
 of high mountains, and is in great meafurc 
 frozen in Winter ; its level is faid by Pallat 
 to be lower than that of the ocean*. 
 
 CHAP. X. 
 
 Of the Temperature of Places lying between tht 
 8 i/? and $$th Degrees of Northern Latitude. 
 
 Lat. 80. ' 
 
 the 28th of June, O. S. An. 1758, at 
 Sea, Mr. Rowlandfon Martin' found the 
 temperature of the air, during the whole 24 
 hours, betwixt 46 and 47 degrees ; the pre- 
 ceding and fucceeding days were much colder, 
 but he was informed that the Summers were 
 often warmer if. In lat. 795o', Lord Mul- 
 grave obferved the greateft heat for two- days 
 to be 58 and the leaft 46*. Thefe obferva- 
 tions agree well with my table. Mr. Martin 
 obferves, that the weather in the polar re- 
 gions is very unfteady ; one hour it blows a 
 violent ftorm, and in the next, there is a dead 
 calm ; neither does it blow long in any one point, 
 but fometimes frorn every point, within the 
 period of 24 hours. After a calm, the north 
 wind fprings up firft ; the fky is feldom per- 
 
 * 3Decouvertes Ruffes, p. 90. J Mem. Stock. 1758. 
 f Mem. Par. 1774. 
 
 fedly
 
 Between Lat. 8 1 . and 55. 55 
 
 fectly clear, and ftorms are much more fre- 
 quent than in lower latitudes. 
 
 On the 1 6th of May, lat. 78 30', the tem- 
 perature of the air being 16, the fea was 
 frozen, but fea-water in hogfheads was frozen 
 in the temperature of 2 8, which agrees with 
 Mr. Nairne's experiments. It is remarkable, 
 that in lat. 80, long, o, Lord Mulgrave found 
 the temperature of the air 44, wind E. N. E. 
 and Mr. Duhamel, the fame day, in Gatinois, 
 lat. 48, long. i, found the wind alfo N. E. 
 and its temperature 71. 
 
 Spitfbergen confifts of a clufter of moun- 
 tains, formed of a fort of flate: Lord Mul- 
 grave meafured one of them, and found it 
 1503 feet high ; the fnow which almoft al- 
 ways covers thefe mountains, renders the 
 neighbourhood of Spitfbergen colder than the 
 open fea. He met with ice for the firft time, 
 July the 4th, in lat. 79 3 1 ', but he fays it is 
 generally firf^ found in lat. 73 or 74. 
 
 Wadfo, in Lapland, lat. 70 5'. 
 
 According to Mr. Hellant, the temperature 
 of fprings, and cotifequently the annual tem- 
 perature is 36; by my table 37,2. The 
 difference arifes from its height over the level 
 of the fea, which is probably confiderable, as 
 the mean height of the barometer for the fix 
 Summer months was about 29,2. 
 
 It has been remarked, that the north fide 
 4 of
 
 56- Of the Temperature of Places, 
 
 of the ridge of mountains, that extend be- 
 twixt Tornea and the North Sea, is not fo 
 cold as the fouthern fide of thofe moun^ 
 tains, for the reafon given p. 42, *. 
 
 Utfjoki, lat. 69 5 2'. 
 
 An. 1758, on the nth of April, it was 
 flill Winter, the temperature in day-time being 
 from 19 to 14 ; from that to the end of the 
 month it varied, being fome days at 41*, and 
 fome at 50, with a S. wind f. 
 
 On the fecond of May, the thermometer 
 was at 1 8 at 12 o'clock, but from the 5th to 
 the 2 1 ft, it was generally at 38 or 40 ; the 
 ten laft days were again cold. 
 
 In June it froze the three firft nights, but 
 from that time till the end of Auguft, there 
 was no more froft ; the warmeft day in June 
 was 61; the nights were generally at 42. 
 
 In July the heat once rofe to 77, yet the 
 Summer was reckoned unufually cold ; the 
 wind was moftly at north. 
 
 j From the I ft to the 1 6th of Auguft, the 
 thermometer was by day from 46 to 61, and 
 at night from 37 to 45 ; from that to the 
 1 9th, it was by day, from 64 to 66; on the 
 27th, it froze at night. 
 
 During the twelve firft days of September, 
 the wind being conftantly at fouth, the wea- 
 
 * ji Collea. Acad. p. 211. f Mem. Stoek. 1759. 
 2 the,r
 
 Between Lat. 81 and 55. 57 
 
 ther was warm, being moftly at 50* ; then the 
 wind turned to N. and the weather was 
 colder, being at night 36, and by day 46 j 
 after the 2 1 ft, it froze every night, and in 
 day-time was at 34. 
 
 The twelve firft days of October were 
 moftly at 32*; after which, the weather be- 
 came much colder, though it thawed fome 
 days ; on the 26th, the cold was below o. 
 
 In November it thawed one day, but the 
 mean temperature of the month was 15. 
 From the 23d, the fun no longer appeared 
 above the horizon, and yet on the 3Oth, the 
 cold did not exceed 23. 
 
 The firft twenty days of December were 
 exceeding cold, though a S. wind moftly 
 reigned, the cold being from 4 to 15 under o ; 
 but what is very furprifmg, from the 22d 
 to the end of the month, the weather was 
 very mild *. 
 
 I have been thus prolix in relating the 
 temperature of this country, as it is from 
 hence that our ftrong northerly winds blow ; 
 and we learn from it feveral curious particu- 
 lars, i ft. We fee that during the entire ab- 
 fence of the fun, the cold is not fo great as 
 might be expected ; and thefe, I believe, are 
 the only obfervations ever made in that inte- 
 refting circumftance. 2dly. That when the 
 countries fouth of Lapland are frozen, the 
 
 * Schwed. Abhand. 1759, p. 228. 
 
 fouth
 
 5# . Of the temperature of Places , 
 
 fouth winds are the coldeft ; for, during the 
 laft and warmeft part of December, the wind 
 was not fouth, but moft probably north ; and 
 then the cold was but a few degrees below 
 congelation. 3dly. We fee that in this high- 
 eft of all inhabited latitudes, the cold is not 
 near fo great even when greateft, as we fhall 
 foon fee it to be in fome countries, lying fo 
 low as lat. 52; and hence we have great rea- 
 fon to think, that the cold of the pole is not 
 fo intenfe as is commonly imagined. 
 
 The barometer varied here from 27,8 to 
 30,4 inches. 
 
 Kola, lat. 6852', long. 30 E. 
 
 In the year 1769, the mean temperature 
 during the following months, was 
 
 March - - 27" 
 April - - 35 
 
 Ma 7 ....- - 54.5 
 June - - 44 
 
 July - - 56 
 
 According to Mayer, it is 420 feet above 
 the level of the fea ; the thermometer was 
 once in May at 73 *. Lapland being moun- 
 tainous, its temperature muft differ much 
 from that of the fea ; the temperature of June 
 was evidently irregular. 
 
 * 2 Bergm. Erde Klot. 14 N. Aft. Petrop. 
 
 Ponoi,
 
 Between Lat. 81. and$$*. 59 
 
 Ponoi, lat. 67, long. 47. 
 
 In the year 1 769, the mean temperature of 
 the following months, was * 
 
 Greateft Cold. Lead. 
 
 March 14 20 - 286 
 
 April 23,8 13,44 24,12 
 
 May 29 9,5 46 
 
 June 38 28 74 
 
 This town lies on a river of the fame 
 name, near the White Sea ; this fea is gene- 
 rally frozen in Winter ; and hence, and from 
 the vicinity of the oppofite land of Siberia, 
 the eaftern coaft of Lapland is much colder 
 than the weftern, or even the northern. 
 
 One day in June, the thermometer flood 
 at 74*; the N. W. wind, paffing over the 
 mountains, is the coldeft, the S. W. the 
 warmeft. 
 
 Umba, lat. 66 39'. 
 
 The fame year, its temperature in the fol- 
 lowing months was j* 
 
 Greateft Cold. Leaft. 
 
 O Q^ T^ 
 
 March 21^,87 - IO 5 75 - 43 
 April 31 ii - 4.6,5 
 
 Ma 7 37>7 - l8 >5 
 
 Umba is alfo fituated near the White Sea t 
 thefe obfervations were made 247 feet above 
 * 14 N. Aft. Petrop. f Ibid. 
 
 t!
 
 6o Of the temperature of Places, 
 
 its level. The interior parts of Lapland being 
 very mountainous, are exceflive cold. 
 
 Abo, lat. 60 27', long. 22 18' E. 
 
 The refult of twelve years obfervations, 
 from 1 750 to 1761, both included, gives the 
 mean annual temperature 39>55r or rather 
 
 " 
 
 Jan. 1 9*58 
 Feb. 21,38 
 March 27,32 
 April 39 
 May 49,46 
 June 60,26 
 July 65,48 
 Auguft6o,26 
 Sept. 50,72 
 Oft. 39,2 
 Nov. 21,29 
 Dec. 20,66 
 
 The greateft cold in that pe- 
 riod happened in Jan. 1760, 
 the thermometer then being at 
 32, but the greateft cold ufu- 
 ally obferved is 7; the ther- 
 mometer is generally 85 days 
 below 32. 
 
 The greateft heat within that 
 period took place in July, 1 757 ; 
 the thermometer {landing at 95, 
 but the greateft ufual heat is 
 
 The ftandard heat of this latitude, is 44*, 
 fo that the difference between the temperature 
 of Abo and the ftandard temperature, is 4 
 degrees ; but its diftance from the Atlantic is 
 540 miles ; and fmce, as above feen, a dif- 
 
 * In reducing foreign thermometers to that of Fahr. 
 as fome fractions are neglected, there is always a differ- 
 ence of about 4 a degree, loft in the totality. 
 
 t Schwed. Abhand. 1763. 
 
 tanot
 
 Between Lat. 8 1 and 55 . 6 1 
 
 tance of 50 miles from the ftandard, lowers the 
 annual temperature 4. of a degree, the dif- 
 tance of 540 miles mould lower it 3,6 degrees. 
 
 Peterfburgh, lat. 59 56', long. 30 24' E. 
 
 The mean annual temperature of Peterf- 
 burgh, during 6 years, from 1762 to 1777, 
 was 38,8. 
 
 i o 
 
 1 6,46 
 
 23 
 
 34,5 
 
 50,2 
 
 59>3 
 
 66,8 
 
 The greatefl cold obferved in 
 Peteriburgh was that at which 
 mercury freezes, viz. 39; 
 but the greateft on a mean of 
 feveral years is 25 ; the 
 froft generally begins in Oc~to- 
 ber, and lafts with little inter- 
 ruption until April. The ther- 
 mometer is generally 145 days 
 below 32. 70 below 19. 30 
 below 8,io below 4, and I 
 at 25. The Winter of 1777 
 was the mildeft long known; yet the thermo- 
 meter flood 69 days'below 32. 26 below 19% 
 7 below 4, and I at 10 
 
 Jan. 
 
 Feb. 
 
 March 
 
 April 
 
 May 
 
 June 
 
 July 
 
 Auguft 61,7 
 
 Sept. 52,8 
 
 O&ob. 40,5 
 
 Nov. 26,8 
 
 Decem.23,4 
 
 , all at noon. 
 
 The greateft Summer heat, on a mean, is 
 79, yet once it amounted to 94. 
 
 The ftandard temperature of the lat. of Pe- 
 terfburgh is 44 P ,3, the difference then is-5,5, 
 which is chiefly owing to its diftance from the 
 
 ftandard
 
 62 Of the temperature of Places^ 
 
 ftandard ; this diftance amounts to 45 degrees 
 of longitude, which in this latitude make 870 
 miles, and, at the rate already mentioned, 
 fhould lower the temperature 5,8 degrees; the 
 neighbourhood of the fea moderates it fome- 
 what. 
 
 It fcarce ever hails at Peterfburgh *. 
 
 Upfal, lat. 59 51', long. 17 47' E. 
 
 From the year 1739 to 1757, the meari 
 yearly temperature was 41,88 j~ 
 
 Jan. 
 
 Feb. 
 
 March 29,12 
 
 April 
 
 May 
 
 June 
 
 25,16 
 
 47> 8 4 
 
 The greateft cold during 
 that period feldom exceeded 
 and only once reached 
 
 5, 
 
 The heat of Summer fre- 
 59,54 quently reaches 80. During 
 62 the Summer of the year I747> 
 Auguft 59,72 which was uncommonly w r arm, 
 Sept. 52,16 there were 61 days above 68, 
 Oclob. 42,36 13 above 77, and 4 between 
 Nov. 33,62 82 and 86. 
 Decem. 27,32 It has been obferved, that 
 the fame fpecies of vegetables bud 31 days 
 iboner at Montpelier, and 28 days fooner in 
 London than in Upfal J . 
 
 * Q Vet. Com, Petrop. 
 2 Bergm. Erde Klot. 
 
 f Schwed. Abhand. 1753. 
 The
 
 Between Lat. 81. ^55. 63 
 
 The ftandard temperature of the lat. of 
 Upfal is 44, 3, the difference then is 2, 42 ; 
 but Upfal is 360 miles from the Atlantic, there- 
 fore its annual mean fhould be 2,4 lower. 
 
 Stockholm, lat. 59 20'. Long. 18, E. 
 
 The mean of 20 years obftrvations, made 
 at Stockholm, gives its annual temperature 
 
 42,39*- 
 
 Jan. 22 9 68 
 Feb. 25,3 
 March 27,9 
 April 
 May 
 June 
 July 
 
 Auguft 6 1, 8 
 Sept. 53,2 
 Odob. 42,9 
 Nov. 34,5 
 Decem. 27,8 
 
 38,7 
 
 49 
 
 61 
 
 6 3>9 
 
 The greateft cold is generally 
 -2*, fcarce ever 5; how- 
 ever, it was once, namely in 
 Jan. 1760, 20. The cold 
 fets in about the month of No- 
 vember, and lafts until the end 
 of March. 
 
 The Summer heat reaches 
 75, and not unfrequently 84. 
 
 The difference of tempera- 
 ture of one year from another 
 amounts to about 5 degrees; 
 
 that is, I above, and 4,5 below the mean 
 above given. 
 
 Mr. Wargentin, in examining aferies of 39 
 years, could not find that any one year re- 
 fembled another ; but he found that the Win*-* 
 ters were formerly more fevere than of late. 
 
 * Mem. Stock. 1778. 
 
 The
 
 64 Of the Temperature of Places > 
 
 The ftandard temperature of the latitude of 
 Stockholm is 44,7i, the difference then is 
 2 0,32 ; its diftance from the ftandard is 43-2 
 miles, therefore it fhould be 2,8 colder. 
 
 Solyfkamfki, lat. 59, long. 54, E. 
 
 The mean temperature of the year 
 as far as I can collect from an imperfect ac- 
 count of it in the Philofophical Tranfactions 
 of the year 1753, was 320,5. 
 
 Solyfkamfki is fituated on 
 the borders of Siberia, weft 
 of the Ourals ; as we have its 
 temperature only for one year, 
 w r e cannot expect it to agree 
 with the rules laid down on 
 this fubject. However, we 
 may remark, that as its diftance 
 from the ftandard is 1 332 miles, 
 it mould be 8*,8 degrees cold- 
 er, and therefore its tempera- 
 ture mould be 36,2, which 
 
 Jan. 
 feb. 8,6 
 March 42,8 
 April 42,8 
 May 49,4 
 June 62 
 July 58 
 Auguft 50,8 
 Sept. 45 
 Odob. 27 
 Nov. 3,4 
 Decem. 10,1 
 
 probably is nearly the truth. 
 
 Of
 
 Between Lat. 81 and 55. 65 
 
 Of the Temperature of Siberia and Karn- 
 fchatika. 
 
 As the temperature of Siberia has fome in- 
 fluence on that of lower latitudes, it will be 
 proper to mention here fome circumftances 
 that are peculiar to it. 
 
 Siberia is not only one of the moft diftant 
 traces of the old continent from the ftandard 
 ocean, but it is attended with another circum- 
 flance, mofl unfavourable to its temperature; 
 for it contains the moft confiderable elevation, 
 not having the appearance of a mountain in 
 the old continent. This elevation even pafles 
 the bounds of Siberia, for it extends from lat, 
 54 to 47, and from long. 55 to 130, eaft 
 of London ; that is, 500 miles from north tjo 
 fouth, and 3315 from eaft to weft. It even- 
 runs ftill further weft, but with diminimed 
 height. This height, as far as I can colled: from 
 various accounts, an.d barometrical obferva- 
 tions, amounts to from 2500 to 3000 feet. 
 Hence the N. E. winds proceeding from this 
 country to Ruffia, Poland, Germany, England, 
 and France, muft be much colder, in propor- 
 tion to the latitude, than thofe that blow oa 
 Sweden, or Scotland, and colder than the mere 
 northerly winds, that come to us over a large 
 tracT: of lea. 
 
 F I have
 
 66 Of the temperature of Places, 
 
 I liave no where met with a feries of ob- 
 fervations taken in Siberia even for one year ; 
 but, it is certain, that not only in Yakutfk, 
 lat. 62, long. 130, E. and Yeniferfk, lat. 58 
 30', long. 92, E. Mercury has often been 
 frozen by the natural cold, which confequently 
 reached, or exceeded 39*; but that the 
 cold is nearly as great at Selengenki and Irkutz, 
 lat. 52 15', long. 105, E. The mean tem- 
 perature of this laft-mentioned place, from 
 O&ober 1780 to April 1781, both included, 
 was 6,8 ; a degree of cold fo great and 
 durable, as I believe has no where clfe been 
 obferved in fo low a latitude f . 
 
 Kamfchatfka is fo diftant from the Atlantic, 
 that its temperature is no way influenced by 
 it, but rather by that of the North Pacific to 
 which it adjoins, and of which we have al- 
 ready treated. On the eaftern coaft, lat. 55, 
 Captain Cook found mow 6 or 8 feet deep 
 in May, and it continued till June; in May 
 the thermometer was moftly at 32, and on 
 the 1 5th of June not higher than 58; in Au- 
 guft its greateft height was 65, and its loweft 
 40 ; in October the hills began to be covered 
 with fnow f ; in November, December, and 
 January, there are violent ftorms accompanied 
 with fnow, the wind at E. and S. E. ; in Ja~ 
 
 * 
 
 * See Dr. Blagden's accurate Hiftory of the Congela- 
 tion of Mercury, Phil. Tranf. 1783. f Mem. Peterfb. 
 1782. t 3 Cooke's Voy. p, 328. 
 
 nuarv
 
 Between Lat. 8 1 and 55. 67 
 
 nuary the cold is fometimes 28, but ge- 
 nerally 8*. 
 
 The northern parts of this peninfula enjoy 
 the moft moderate weather, being chiefly in- 
 fluenced by the north fea, whofe temperature, 
 I believe even in Winter, is milder than that of 
 the fea below the ftreights, that feparate Afia 
 from America. 
 
 Churchill, or Prince of Wales' s Fort, lat. 59, 
 long. 92, W. 
 
 The temperature of 1 2 months, from Sep- 
 tember 1768, to the end of Auguft 1769, was 
 24,7; the mean of each being as followsf : 
 
 1769 January 28 
 
 February 20 
 
 March 1 2 
 April 
 
 May 
 June 
 
 Here the temperature 
 is 20 degrees below the 
 ftandard, but the Winter 
 of 1769, was rather fe- 
 vere, even in Europe. 
 However, from the dif- 
 ferent temperature even 
 of Summer, we may con- 
 clude that the weather is 
 colder here than at Soly- 
 fkamfki. 
 
 20 
 38 
 ^o 
 
 58 
 
 Auguft 50 
 1768 September 42 
 Odober 28 
 November 5 
 December 18 
 
 In July the thermometer was one day at; 
 
 85- 
 
 * Steller. f Phil. Tranf. 1770, p, 148, &c. 
 
 F 2 Nain
 
 68 Of the Temperature of Places* 
 
 Naiii in Labrador, lat. 57. 
 
 From obfervations made here during the 
 latter part of the year 1778, fome part of the 
 year 1780, and the whole of the year 1779, 
 the mean feems to have been 30^54, that of 
 each month being 
 
 Jan. 
 Feb, 
 March 
 April 
 
 May 
 June 
 
 3>5 
 
 7.5 
 2 79 
 
 4 2 ' 6 
 
 5>2 
 
 45 
 
 The temperature of theftand- 
 ard is 46,7, the difference then 
 is 1 6,1 6; but it muft be con- 
 fidered that the year 1779, was 
 remarkably cold even in Eu- 
 rope. 
 
 The greateft heat obferved 
 in the year 1780, was 84 de- 
 grees, and this was in July ; 
 the greateft cold in 1 779, was 
 36*. 
 
 The country of Labrador is 
 exceeding barren, interfered 
 with chains of lakes, deep bays, high craggy 
 mountains, and unfruitful vallies: there is no 
 appearance of Summer before July, though the 
 Winters are faid to be lefs fevere than for- 
 merly. 
 
 The fea is covered with large bodies of ice- 
 that let in from the north, in Spring and 
 Summer * . 
 
 Auguft 
 Sept. 
 
 October 34 
 Novem. 26,5 
 Decem. 6,5 
 
 * Phil. Tranf. 1781. 
 
 f Phil. Tranf. 1774. 
 
 Edinburgh,
 
 Between Lai. 81 and 55. 
 
 Edinburgh, lat. 55 57, long. 3 W. 
 
 Thefe obfervations were made at Hawkhill, 
 about i mile from Edinburgh, and 103 feet 
 over the level of the fea. They comprehend a 
 mean of 3 years, from 1772 to 1774; this 
 mean appears to be 47^,7 * . 
 
 J an - 345 
 
 Feb. . 36,6 
 
 March 41,7 
 
 April 46, ^ 
 
 May 
 June 
 
 July 
 
 Auguft 
 Sept. 54,3 
 October 49,7 
 Novem. 41,1 
 Decem. 38,9 
 
 5>4 
 57>5 
 60,6 
 60,6 
 
 The temperature of the ftand- 
 ard is 47,5, fo that the dif- 
 ference is inconfiderable. Edin- 
 burgh is near the German fea, 
 which we have feen, to be 
 upon the whole 2 degrees 
 warmer than the ftandard; but 
 land, in this latitude, retaining 
 fnow, long after the degree of 
 cold that produces it ceafes, is 
 always fomewhat colder upon 
 the whole, let the circumftances 
 be ever fo favourable, than the 
 fea.- 
 
 Phil. Tranf. 1775, p. 462, 
 
 C H A P.
 
 70 Of the temperature of Places, 
 
 CHAP. XL 
 
 Of the temperature of P laces , Jltuated between 
 the 55//J and ^oth Degrees of Latitude. 
 
 Franeker, lat. 53% long. 5 42' E. 
 
 DURING five years, from 1777 to 1781, 
 the mean temperature of this town was 
 52,6. The monthly, as follows: 
 
 Jan. 3272 The greateft ufual cold is 
 Feb. 38,47 12, the greateft heat 82. 
 March 44,64 The ftandard temperature of 
 April 50,17 this latitude is 5O,2, the dif- 
 May 59,40 ference is 2,4 ; the reafon of 
 June 64,71 which is, that all continents, 
 July 68,80 if flat, are in Summer much 
 Auguft 69,03 warmer than the ftandard, and 
 Sept. 62,9 1 particularly thofe which border 
 O&ob. 55,04 on the German fea, as that fea 
 Nov. 45,54 is, upon an average of the 
 Dec. 39,82 whole year, 2 degrees warmer 
 than the Atlantic ; but in Win- 
 ter, the German fea is colder than the ftandard, 
 and Holland, in general, is much expofed to 
 N. E, Siberian winds. 
 
 Berlin,
 
 Between Lat. 55 and 40. 71 
 
 Berlin, lat. 52 32', long. 13* 31' E. 
 
 According to Mr. Beguelin's obfervations, 
 the annual average temperature of Berlin, for 
 15 years, (from 1769 to 1782) was 49, and 
 after an attentive examination, he could not 
 find that the temperature diminilhes*. 
 
 Upon infpecting obfervations of 8 years, 
 I find the thermometer is generally 50 days 
 below 32. 
 
 The ftandard temperature of this latitude is 
 50,8, the difference is i, 8 ; as its diftance 
 from the ftandard is about 840 miles, it mould 
 be cooled 5,4 degrees, were it not for the in- 
 tervention of the German fea, which being 2 
 degrees warmer than the ftandard, obviates in 
 fome meaiure, the effects of its diftance from 
 the ftandard, But as this fea is 240 miles 
 diftant from it, inftead of 2 degrees, it gains 
 but i,6 from it, which mould ftill leave it 
 3, 8 colder than the ftandard: but again, it 
 has the Baltic within 120 miles on the north 
 of it, which tempers the north winds, and 
 leaves it the moderate temperature which it 
 enjoys. 
 
 The influence of the neighbourhood of 
 the Baltic muft be allowed, when it is confi- 
 dercd, that the temperature of Berlin is higher 
 than that of Drefden, Altenburgh, or Gotha, 
 whofe latitude is one degree lower, but more 
 diftant from the Baltic. 
 
 * Mem. Berl. 1782. 
 
 F 4 Lyndon
 
 72 Of the "Temperature of Places^ 
 
 Lyndon in Rutland, lat. 52 30', long, o 3' W. 
 
 The mean annual temperature of Lyndon 
 during 15 years, (from 1771 to 1785) com- 
 municated to me by that affiduous and accurate 
 obferver, Mr. Thomas Barker, is 48,O3, that 
 of the ftandard 5O,6, the difference 2,6. 
 But the mean height of the barometer is but 
 29,4 inches, which, as the temperature of the 
 nearer! fea is 52,6, gives an elevation of 540 feet 
 nearly. This fea is but 40 miles diftant, there- 
 fore this elevation, according to the principles 
 laid down in the 2d feclion of the 5th chapter, 
 fhould caufe a diminution of i ,4 of a degree. 
 Befides, Lyndon is 150 miles from the Irifh 
 fea, the neareft branch of the Atlantic, which 
 fliminimes the temperature I degree more : the 
 remaining diminution is owing to its neigh- 
 bourhood to the Englim Apennine, by which 
 the wefterly winds are ftill further cooled. 
 
 Ley den, lat. 52 10', long. 4 32' E. 
 
 Leyden is nearly in the fame circumftances 
 as Franeker, but being farther from the Ger- 
 man fea, its temperature exceeds the ftandard 
 only 1,35 degrees. 
 
 London,
 
 Between Laf. 55 and 4 
 
 73 
 
 London, lat. 51 31'. 
 
 From B. mean of the obfervations made at 
 the houfe of the Royal Society, from the year 
 1772 to the year 1780, it appears that the 
 annual temperature of London is 5i,9, or in 
 round numbers 52 ; the monthly temperature 
 as follows: 
 
 Jan. 
 Feb. 
 
 March 
 April 
 
 May 
 Jane 
 
 Auguft 
 
 Sept. 
 
 Odob, 
 
 Nov. 
 
 Pec. 
 
 359 
 
 46,4 
 
 49.9 
 
 56,61 
 
 63,22 
 
 66,3 
 
 65,85 
 
 5 9 A3 
 
 52,81 
 
 44,44 
 41,04 
 
 The greateft ufual cold is 
 20, and happens in January; 
 the greateft ufual heat is 8 1 p , 
 and happens generally in July. 
 
 The limits of the annual 
 variation are 2,5 degrees, that 
 is, one degree above and i,5 
 below the mean. 
 
 The greateft variations of the 
 mean temperature of the fame 
 month in different years, arc 
 as follows : 
 
 Jan. 6 
 Feb. 5 
 March 4 
 April 3 
 
 May 2, 5 
 June 2 
 July 2 
 Aug. 2 
 
 Sept. 3 
 Od. 4 
 Nov. 4 
 Dec. 3 
 
 Hence we fee that the Summers differ much 
 lefs, than the Winters. 
 
 The
 
 74 Of the Temperature of Places, 
 
 The moft ufual variations of temperature 
 within the fpace of 24 hours in every month, 
 are 
 
 Jan. 6 
 Feb. 8 
 March 20 
 April 1 8 
 
 May 14^ 
 June 12 
 July 10 
 Aug. 15 
 
 Sept. 1 8 
 Ot. 14 
 Nov. 9 
 Dec. 6 
 
 Thence the origin of vernal and autumnal 
 colds. 
 
 The mean height of the lower term of con- 
 gelation is moft probably in 
 
 Feet Feet Feet 
 
 Jan. 1800 May 7369 Sept. 8268 
 
 Feb. 3084 June 9480 Oft. 6240 
 
 March 4314 July 10380 Nov. 3715 
 
 April 5400 Aug. 10126 Dec. 2770 
 
 The lower term of congelation is to the 
 upper, nearly as 10 to 18. 
 
 The ftandard temperature of the latitude of 
 London is alfo 52 ; for though it mould be 
 cooled i,2, by reafon of its diftance from the 
 ftandard, yet it mould be heated nearly as much 
 by its proximity to the German fea. However, 
 proportionably to its latitude, it is much colder 
 in Winter at London than at Edinburgh ; for 
 we have feen the mean temperature of Edin- 
 burgh
 
 Between Lot. 55 and 40. 75 
 
 burgh in January to be 34,^, and that of 
 London is 35,9 ; the reafons of which are, 
 i ft. That Edinburgh is not expofed to the 
 Siberian winds, as London is. 2dly. That 
 Edinburgh is nearer to the fea. 3dly. Becaufe 
 the rigour of the northerly winds is very little 
 moderated, if not increafed, in patting from 
 Scotland to us, particularly if the furface of 
 the earth is covered with fnow ; and hence, 
 if we may believe Dr. Smollett *, the Winters 
 are fometimes milder at Edinburgh, than at 
 London. 
 
 Dunkirk, lat. 51 02', long. 2yE. 
 
 The temperature of Dunkirk, on a mean of 
 ten years, as given by Pere La Cotte, was 
 549't- 
 
 Jan. 41 
 Feb. 44 
 March 46 
 
 A P ril 53 
 May 60 
 
 June 65 
 
 July 68 
 Auguft68 
 
 Sept. 64,6 
 
 Oct. 53,4 
 
 Nov. 46,5 
 
 Dec. 40 
 
 * Travels to Italy. 
 Cotte, p. 360. 
 
 The temperature of the ftand- 
 
 ard latitude is 52 4', the dif- 
 
 r o i . i i 
 
 ference is 2 5'; this proceeds 
 
 from its vicinity to the German 
 fea,which,as has already been of- 
 ten noticed, is upon the whole, 
 two degrees warmer than the At- 
 lantic ; befides, the Britifh chan- 
 nel, which is at no great diftance 
 on the S. Weft, tends much to 
 render its temperature milder. 
 
 f Meteorolog. de La 
 
 Manheim,
 
 2'E. 
 
 76 Of ike ^Temperature of Places, 
 
 Manheim, lat. 49 2 7', long. 9 
 
 The temperature of this capital of meteoro- 
 logy, during the years 1781 and 1782, was 
 
 si's'- 
 
 The ftandard temperature is 
 5 2 6'. Its diftance from the 
 Britim channel is about 200 
 miles, and from the German 
 fea fomewhat lefs ; fo that its 
 temperature mould be nearly 
 one degree below the ftandard. 
 
 Jan. 35 e o8 
 Feb. 35,8 
 March 4*3,9 
 April 52,6 
 May 58,2 
 June 68,7 
 July 70,9 
 Auguft66,2 
 Sept. 62,3 
 
 oa. 38,5 
 
 Nov. 48,08 
 Dec. 35,6 
 
 Rouen, lat. 49 26', long. iW. 
 
 The mean of the years 1779 and 1780 was 
 50 7', but it muft be remarked, that the Win- 
 ter of 1 779 was uncommonly cold *. 
 
 Jan. 2896 
 Feb. 36,83 
 March 45, 99 
 April 49,88 
 
 The ftandard temperature is 
 52 6', to which the real tempe- 
 rature of Rouen mould approach 
 considerably, as its diftance from 
 
 * Mem. Societ. Med. Paris. 
 
 the
 
 Between Lat. 55 and 40. 
 
 77 
 
 the channel is inconfiderable ; 
 hence it is probable, that De- 
 cember, January, and February, 
 are 3 degrees below the ufual 
 mean of thefe months. 
 
 May 6o57 
 
 June 62,48 
 
 July 65,41 
 Auguft68,n 
 
 Sept. 62,43 
 
 o<a. 53,82 
 
 Nov. 38,86 
 
 Dec. 34,70 
 
 Ratrfbon, lat. 48 56', long. 12 05' E. 
 The mean of the years 1781 and 1782 was 
 49>35- 
 
 Jan. 3o52 
 Feb. 30,76 
 March 40,2 1 
 April 50,22 
 May 59,87 
 June 68,52 
 July 70,4 
 Auguft68,22 
 Sept. 6 1, 68 
 Oa 45,49 
 Nov. 35,22 
 Dec. 31,14 
 
 The ftandard of this latitude 
 is 53,8, the elevation of Ratif- 
 bon is confiderable, as the mean 
 height of the barometer during 
 thofe years was 28,88, but with 
 refpecl to its diftance from the 
 neareft fea, this elevation is in- 
 confiderable ; its diftance from 
 the ftandard, is 580 miles, which 
 mould lower its temperature 
 2,32. Its true temperature ispro- 
 bably on that account 51, 48. 
 
 Paris, lat. 48 50. long. 2 25' E. 
 
 The temperature of this celebrated city, de- 
 duced from a icries of obfervations, uninter- 
 
 ruptedly
 
 78 Of the Temperature of Places, 
 
 ruptedly continued for 7 1 years ; that is, front 
 1699 to 1770, was 5i,97, or in round num- 
 bers 52*; the monthly as follows. 
 
 J an - 345 
 Feb. 39 
 March 43, 25 
 April 51,2 
 May 59,2 
 June 66 
 July 68,75 
 Auguft68 
 
 The greateft heat during that 
 period happened in the year 
 1720, amounting to 104; the 
 greateft cold was obferved in 
 the year 1 709, the thermome- 
 ter being at 1; but a ftill 
 greater was felt in the year 
 1776, namely 4,5. 
 
 Sept. 63,5 
 
 Ot. 52 The ftandard temperature of 
 
 Nov. 42 this latitude is 53,9. Paris then, 
 Dec. 36,8 by thefe obfervations, is 1,9 de- 
 grees colder than its ftandard ; 
 its diftance from the wideft part of the Bri- 
 tifh channel, oppofite to Coutances, in Nor- 
 mandy, is 154 miles, which fhould diminifh 
 its temperature one degree : other parts of the 
 channel are nearer, but perhaps too narrow to 
 have any influence at a confiderable diftance ; 
 but I am inclined to think, that the old ob- 
 fervations were faulty, and that its true tem- 
 perature is at leaft 53^, if not more ; for that 
 of the cave of the Obfervatory, is 53,5 f> 
 and if we confider, that befides the vicinity of 
 the Atlantic on the weft, the northerly winds 
 
 * Meteorol. de La Cotte. f Van Swind. Therm, p. 82. 
 
 pafs
 
 Between Lat. 55 and ^ , 79 
 
 pafs over a comparatively fmall tract of land, 
 before they arrive at it, we fhall fee reafon to 
 think, that its temperature cannot be pne de- 
 gree below that of the ftandard. 
 
 Troyes, lat. 48 1 8', long. 4 P lo'E. 
 
 During the years 1779, 80, and 81, the 
 mean heat of this capital of Champagne, was 
 
 53,'7"- 
 
 Jan. 3 3 1 2 
 
 Feb. 39,49 
 March 48,04 
 
 A P ril 53>97 
 
 Ma 7 5937 
 
 June 65,14 
 
 July 68,44 
 
 The ftandard temperature is 
 54,4 ; the difference i,43 ; its 
 diftance from the Atlantic is 
 280 miles, by which it mould 
 be cooled i,8 ; perhaps the 
 foil contributes to make it fome- 
 what warmer. 
 
 Sept. 63,34 
 
 oa. 54,27 
 
 Nov. 43,70 
 
 Dec. 38,89 
 
 Vienna, lat. 48, 12', long. i622' E. 
 
 Its temperature, upon an average of the 
 years 1779, and 1780, was 5 1^34 f. 
 
 Jan. 275 j The ftandard temperature is 
 Feb. 33,23 j 54, 6 ; the difference 3,26"; but 
 
 * Mem. Socict. Med. Par. f Ibid, 
 
 the
 
 So Of the Temperature of Places, 
 
 March4628 
 
 Ap ril 53>37 
 May 63,38 
 
 June 64,85 
 July 68,56 
 Auguft68,78 
 Sept. 61,36 
 
 oa. 52,81 
 
 Nov. 40,99 
 Dec. 34,98 
 
 the diftance of Vienna from 
 the ftandard, is 770 miles, which 
 (hould lower its temperature five 
 degrees. 
 
 Dijon, lat. 47 19', long. 4 57' E. 
 
 By obfervations of four years, ending in 
 1781, the temperature of this town is 
 5 2,8 *. 
 
 Jan. 33o6 
 
 Feb - 37^43 
 March 47,8 6 
 
 A P ril 5 2 >5 2 
 
 May 60,96 
 
 June 65,69 
 
 July 69,4 
 
 Sept. 62,48 
 
 Od. 52,86 
 
 Nov. 43,41 
 
 Dec. 36,72 
 
 The ftandard temperature is 
 55,3 ; the difference 2,5 ; but 
 the diftance of Dijon, from the 
 ftandard, is 260 miles, which 
 gives a diminution of 1,7 de- 
 grees. It is cooled fomewhat 
 further, by a ridge of moun- 
 tains to the weft of it, and the 
 chain of Jura, about 60 miles 
 to the eaft. 
 
 * Mem. Societ. Med. Par. 
 
 Nantes,
 
 Between Lot. 55 and 40*. 8 1 
 
 Nantes, lat. 47 13', long. i 28'E. 
 
 This city being little diftant from the ftand- 
 ard, it may be expected that its temperature 
 fhould fcarce differ from it; and in effecl:, 
 by four years obfervations, it amounts to 
 55,53 degrees, and that of the flandard is 
 55%5 * 
 
 J an - 3775 
 Feb. 42,25 
 
 March 5 0,1 7 
 
 A P ril 54>7 6 
 May 60,85 
 June 65,29 
 July 69,61 
 
 Sept. 65,25 
 
 Oft. 56,25 
 
 Nov. 48,87 
 
 Dec. 42,34 
 
 Poidtiers, lat. 46 39', long. o 30' E, 
 
 From obfervations of five years, that is, 
 from 1777 to I 7^ 1 inclufively, the tempera- 
 ture of this city fhould be 53 ? 8. 
 
 Jan. 34^4 
 Feb. 40,27 
 March 48, 96 
 April 52,74 
 May 58,90 
 
 But the ftandard temperature 
 is 55,9 ; the difference 2,1, 
 which is too great ; for the 
 Atlantic is but 70 miles diftant, 
 which fhould occafion a dimi- 
 
 * Mem, Societ. Med. Par. 
 
 G nution
 
 82 Of the Temperature of Places , 
 
 June 64o8 nution of only \ a degree, if 
 
 July 69,48 the intervening woods do not 
 Auguft-0,86 increafe the effect of diftance. 
 
 Sept. 63,40 
 
 Oa. 54,54 
 
 Nov. 46,35 
 
 Dec. 40,27 
 
 Laufanne, lat. 46 31', long. 6* 50' E. 
 
 The temperature of this town, deduced 
 from obfervations for ten years, by that intelli- 
 gent and accurate obferver Dr. Verdeil, was 
 480,87*. 
 
 Jan. 286 The ftandard temperature is 
 
 Feb. 36,4 56; the difference is 7*^13; 
 March 40,3 but the diftance of Laufanne 
 April 48,2 from the Atlantic Is 388 miles; 
 May 56,7 this produces a diminution of 
 June 64,6 2,58 degrees in its annual tem- 
 July 65,7 perature. Its elevation over the 
 Auguft66,6 neareft fea (the Mediterranean) 
 Sept. 59,7 is 1 700 feet ; its diftance from 
 Oct. 49,5 this fea 210 miles ; this eleva- 
 Nov. 40,1 tion exceeds the rate of 8 feet 
 Dee. 33,8 per mile, and therefore gives a 
 diminution of -J- of a degree 
 on every 200 feet, which makes in all 2,43 
 degrees ; which added to the diminution arif^ 
 
 * i Mem. Laufanne.
 
 Between Laf. 55 and 40. 83 
 
 ing from diftance, make the total diminution 
 5,01 degrees; the remaining two degrees mufl 
 be attributed to the mountains in its vicinity, foi? 
 on the weft it has the range of Jura, which in- 
 tercepts its communication with the ocean, and 
 the warmer parts of France ; on the fouth, the 
 mountains of the Pays de Vaud and Savoy, 
 and to the eaft, at no great diftance, the 
 frozen mountains of SwifTerland. 
 
 The greateft heat obferved during that pe- 
 riod, was 87, the greateft cold 70. 
 
 Aftracan, lat. 46 21', long. 51 E. 
 
 Though I have not, as yet, met with a 
 regular ieries of obfervations, made in Aftra- 
 can ; yet, on account of the great difference 
 of its temperature from that of all other places 
 in Europe, fituated under the fame parallel ; 
 the few that have been made there, deferve par- 
 ticular notice ; and fo much the more, as they 
 confirm the theory, of the effects of diftance 
 from the fea ; the three firft and laft were 
 made in 1780*. 
 
 Aftracan. Peterfburgh. 
 
 Jan. i6,5 8 
 
 Feb. 1 8,6 - 20 
 
 March 32 - 25 
 April 52 
 
 * Mem. Peterfb. 1782. 
 
 G 2 JVUy
 
 84 Of the Temperature of Places , 
 
 Aftracan. 
 
 * May 68' 
 An. 1746 June 74 
 July 80 
 AuguftSo 
 Sept. 
 
 PAerfburgh, 
 
 Gel:. 47 40 
 
 NOV. 38 - 22 
 
 Dec. 15 17 
 
 The diftance of Aftracan from the neareft 
 part of the Atlantic, to wit, the Bay of Bif- 
 cay, is 2760 miles, which by the rule, chap. 5. 
 i. mould caufe a diminution of 11 in its 
 temperature, and leave it 45*,4, which pro- 
 bably, is its true mean annual temperature. 
 It is true the Cafpian is clofe to it, and the 
 Black Sea not half the diftance of the Atlantic ; 
 but the Cafpian is itfelf in great meafure frozen 
 in Winter, as the Black Sea is faid to have 
 often been, and its communication inter- 
 cepted by mountains. Elevation certainly con- 
 tributes nothing to the rigour of the Winter 
 in Aftracan, for the barometer is generally 
 above 30 inches ; but the fandy defarts in its 
 neighbourhood probably contribute to the 
 extraordinary heats it experiences^ 
 
 * Mem. 3erl. 1746. 
 
 Montreal
 
 Between Lat. 55 and 40. 85 
 
 Montreal, lat. 45 35', long. 73 \V. 
 
 It appears from a grofs eftimate of the ob- 
 fervations of Mr. Gaultier and Mr. Bar, both 
 of which are too imperfect and confufed to 
 allow me to fpecify their precife refult, that 
 the celd of Canada is as great, if not greater, 
 than that of Aftracan ; but the Summer's heat 
 is not near ib great, nor does it laft fo long as 
 at Aftracan*. 
 
 Padua, lat. 45 23', long. 12 E. 
 
 According to the obfervations of the cele- 
 brated meteorologift Mr. Toaldo, the mean 
 temperature of this city during the years 1781 
 and 1782 was 52,2. 
 
 Jan. 332 
 
 Feb. 34,7 
 
 March 45,2 
 
 A P ril 55>3 
 
 May 58,4 
 
 June 71,9 
 
 July 7 6 >5 
 Auguft 75 
 
 Sept. 62 
 
 Oftob. 51,9 
 
 The ftandard temperature is 
 5 7, 2 ; the difference is 5, but 
 the diftance of Padua from the 
 Atlantic is 600 miles, by which 
 it mould be cooled 4 degrees. 
 In Winter it is ftill further cooled 
 by its vicinity to the Euganean 
 mountains ; and in Summer alfo, 
 by the neighbourhood of the 
 Adriatic: the Mediterranean is 
 
 * Mem. Par. 1744, &c. See an ingenious Explanation 
 of Gaul tier's Thermometer, by Mr. Gauflen of Mont- 
 pelier, in 17 Roz. p. 39. 
 
 G 7 indeed
 
 86 Of the Temperature of Places , 
 
 Nov. 41,2 1 indeed much nearer to it than 
 Dec. 36,9 1 the ocean, but its influence is 
 intercepted by the interpofition 
 of the Apennines; fo that its true temperature 
 feems to be 52,6 or 52,8. 
 
 Rhpdez in Guienne, lat. 45 21', long. 
 2* 39 E. 
 
 Its temperature during the years 1 779 and 
 1780 was 50^94, or 51 ; but as the Winter 
 was uncommonly cold, this is probably much 
 below the mean of common years. 
 
 The ftandard temperature is 
 57,2, difference 6, 2 ; its dif- 
 tance from the ftandard 150 
 miles, by which its temperature 
 is lowered i ; but the mean 
 height of the barometer during 
 
 3 2 33 
 eb. 36,72 
 
 March 45,21 
 April 48,20 
 
 59>7 8 
 62,14 
 
 June 
 
 July 64,96 thefe two years was 27,75 
 Auguft 70,36 inches ; and though I cannot, 
 Sept. 63,04 from this fmgle circumftance, 
 Oclob. 50, deduce the height with preci- 
 Nov. 40,32 fion, as it is uncertain whether 
 Dec. 38,07 this be the true mean mercu- 
 rial height ; which feems on 
 the contrary rather improbable, as the tempe- 
 rature of this period was colder than ufual, 
 yet it may certainly be inferred, that the ele- 
 vation of this place cannot be much lefs than 
 2000 feet, which muft lower the tempera- 
 ture 3,3 degrees ; and this depreffion added 
 
 to
 
 Between Lot. 55 #^40. 87 
 
 to the former, gives 4,3 degrees, fo that the 
 real temperature may be 52,9 or 53 degrees. 
 
 Bourdeaux, lat. 44 50', long. o36' W. 
 
 Upon a mean of 5 years, (from 1777 to 
 1781) its temperature was 56, 8. 
 
 Jan. 3 888 
 Feb. 44,82 
 March 51,71 
 April 57,10 
 May 61,56 
 June 66,02 
 July 71,19 
 Auguft 75,24 
 Sept. 61,15 
 
 oa. 59,04 
 
 Nov. 49,68 
 Dec. 43,92 
 
 The ftandard temperature is 
 57,6, difference 0,8 ; this is 
 chiefly owing to the uncom- 
 mon cold of the 3 iirft months 
 of the years 1777 and 1779, 
 which were colder in propor- 
 tion in the fouth of France than 
 elfewhere. In the year 1781, 
 the mean heat was 58,32,and 
 in moft of the other years 57; 
 fo that the true temperature is 
 very nearly that of the ftandard. 
 
 Montpelier, lat. 43 36' long. 3 73' E. 
 
 Its temperature from 1777 to 1781 was 
 6o',8 7 . 
 
 The ftandard temperature is 
 
 Jan. 
 Feb. 
 
 42 21 
 
 45,58 
 
 March 50,09 
 
 April 
 May 
 
 57,82 
 66,51 
 
 June 72,63 
 July 79,06 
 Auguft 79,33 
 Sept. 71,64 
 
 59; Montpelier is then 1,87 
 degrees warmer. Its diftance 
 from the Atlantic is 260 miles, 
 by which it fhould be cooled 
 i ,6 degrees ; but its tempera- 
 ture is governed chiefly by that 
 of the Mediterranean, which 
 lying to the fouth of it in ftill 
 G 4 warmer
 
 88 
 
 oa. 63,22 
 51*97 
 
 Of the Temperature of Places, 
 
 Nov. 
 Dec. 
 
 warmer latitudes, commune 
 cates its temperature to it both 
 46,48 Summer and Winter ; but 
 Winters, during which eafterly 
 winds from the mountains of Savoy and Pied- 
 mont prevail, muft be much colder. The 
 foil on which Montpelier ftands, which is 
 fandy and ftony, muft contribute much to 
 its heat. 
 
 Marfeilles, lat. 43 19', long. 5 27' E. 
 
 By obfervations of 34 years, namely, from 
 1745 to 1778, the temperature of this town 
 was found to be 6i,8 #. 
 
 But the temperatures of the 
 years 1780 and 1781, were 
 much lower; the mean of thefe 
 added to the foregoing is 6 1 ,7. 
 
 Jan. 
 
 459 
 
 Feb. 
 
 49 
 
 March 
 
 52,6 
 
 April 
 
 60,2 
 
 May 
 
 68,5 
 
 June 
 
 73*6 
 
 July 
 
 78,2 
 
 Auguft 
 
 79 
 
 Sept. 
 
 71,2 
 
 oaob. 
 
 60,2 
 
 Novem. 
 
 53 
 
 Dec. 
 
 49 
 
 The 
 
 ftandai 
 
 temperature is 59*,!; but 
 like Montpelier the temperature here is in- 
 fluenced chiefly by the Mediterranean on which 
 it borders ; the foil alfo is fandy and ftony. 
 * Mem. Societ. Med. Par. 1778. 
 
 Mont
 
 Between Laf, 55 and 40, 
 
 Mont Louis in Rouffillon, lat. 42, long. 2 
 46' E. 
 
 Mont Louis lies about 30 miles fouth of 
 Perpignan, among the Pyrenees, and is one of 
 the higheft inhabited parts of Europe. The 
 mean height of the barometer being 24,65 
 inches, its temperature during the years 1780 
 and 1781, was 44. 
 
 3^44 
 
 Jan. 
 
 Feb. 
 
 March 41,22 
 
 April 40,85 
 
 May 
 
 June 
 
 Aug. 
 Sept. 
 
 The ftandard temperature is 
 60, 3, the difference i6,3; its 
 
 diftance from the Atlantic is 
 208 miles, by which it fhould 
 49,21 be cooled i,3 of a degree, but 
 52,81 its height over the Mediterra- 
 58,77 nean, from which it is about 
 58,32 40 miles diftant, is 4500 feet. 
 53,26 This elevation being above. 1 5 
 OcT:ob. 44,82 feet per mile, caufes a dimi- 
 Nov. 35 nution of i a degree in every 
 Dec. 33>9 200 feet, arxl confequently in 
 this cafe, of 11,25 degrees. 
 Hence I2*,28 degrees are accounted for; by 
 its fituation among mountains covered with 
 fnow in Winter, and much loftier, it muft be 
 ftill further cooled, though not, perhaps, 
 as much as during thefe 2 years, which cannot 
 be deemed to exhibit its true mean tempera- 
 ture. 
 
 Cambridge
 
 90 Of the temperature of Places^ 
 
 Cambridge in New England, lat. 42 25', 
 long. 71 W. 
 
 By a mean of the obfervations made here 
 during the years 1781 and 1783, its tempera- 
 ture appears to be 5O,3, that is, about 10 de- 
 grees below the European ftandard. The in- 
 equalities within each month are another pe- 
 culiarity of the American climates, which I 
 {hall here exhibit. 
 
 Mean Greateft Heat Lead 
 
 Jan. 2 9 5 4 8,5 o 
 
 Feb. 37,5 55 
 
 March 36,5 - 59 13 
 
 April 48,5 - 77 35 
 
 May 58,5 77 - 41 
 
 June 68,5 - &5 5 
 
 July 73 91 - 62 
 
 Aug. 71-92 - 62 
 
 Sept. 63,5 85 - 45 
 
 Oftob. 50,5 68 - 38 
 
 Nov. 36 57 19 
 
 Dec. 31 6 1 12* 
 
 * American Tranfaftions, Vol. i. p. 
 
 Ipfwich
 
 Between Lat. 55 and 40*. 91 
 
 Ipfwich in New England, lat. 42 38', 
 long. 70 45'. 
 
 The mean temperature of the years 1781, 
 1782, and 1783, was 50, 17. 
 
 Mean Higheft Loweft 
 
 Jan. 30 49" - 6 
 
 Feb. 30 53 i 
 
 March 38 56 16 
 
 April 48 80 - 37 
 
 May 56,5 78 45 
 
 June 68 88 51 
 
 July 70,5 89 60 
 
 Aug. 70 88 55 
 
 Sept. 63,5 86 45 
 
 Odtob. 51,6 72 40 
 
 Nov. 39 55 22 
 
 Dec. 37 55 14* 
 
 But it muft be remarked that the thermo- 
 meter was not perfectly expofed to the air. In 
 Jan. 1 78 3, a thermometer without doors flood 
 at 10 below o; this. Winter was here alfo un- 
 commonly fevere. 
 
 On the coaft of America the eaft winds are 
 the cooleft in Summer, and the warrneft in 
 Winter, as might be expected, they pafling 
 from the fea. 
 
 * i Amer. Accad. p. 349. 
 2 Apala-
 
 92 Of the temperature of Places , 
 
 Apalachian or Blue Mountains, between New 
 York and Albany, lat. 42. ' 
 
 Mr. Kalm, in the month of July, when the 
 external heat was 64, found the temperature 
 of a deep well 49; that is n below the 
 European ftandard*. 
 
 Madrid, lat. 40 25' long. 3 20' E. 
 
 The ufual heat in Summer is faid to be 
 from 75 to 85 ; even at night it feldom falls 
 below 70 ; the mean height of the barometer 
 is 27,96. It feems to be about 1900 feet above 
 the level of the fea f . 
 
 CHAP. XII. 
 
 Of the Temperature of Places, ftuated between 
 Lat. 40 arid Lat. o. 
 
 Philadelphia, lat. 39 56', long. 75 09' W. 
 
 THE temperature of the deepeft wells 
 near this city was found to be 52,5, 
 that is, about 10 below the European ftand- 
 ard J. 
 
 * Mem. Stock. 1771. f Mem. Par. 1777, p. 14.6. 
 Mem. Stock. 1771. 
 
 Pekija,
 
 Between <JLat. 40 and o. 
 
 93 
 
 Pekin, lat. 39 54', long. 116 29' W. 
 
 By 5 years obfervations its annual mean 
 temperature was found to be 55,5. 
 
 Jan. 
 "Feb. 
 
 >75 
 
 >75 
 
 20* 
 32 
 
 March 48 
 April 59 
 May 72 
 June 83 
 July 84 
 Auguft83 
 Sept. 63 
 Odob. 52 
 Nov. 41 
 Dec. 27 
 
 of its extent. 
 
 The temperature of the At- 
 lantic under this parallel is 62, 
 but the Jftandard of this part of 
 the globe is the North Pacific, 
 which is here 4 or 5 degrees 
 colder than the Atlantic. The 
 Yellow Sea is the neareft to 
 Pekin, being about 200 miles 
 diftant from it ; but it is itfelf 
 cooled by the mountainous 
 country of Corea, which in- 
 terpofes between it and the 
 ocean, for a confiderable part 
 Belides, all the northern parts 
 of China (in which Pekin lies) muft be cooled 
 by the vicinity of the mountains of Chinefe 
 Tartary, among which the cold is faid to be 
 exceffive. 
 
 The greateft cold ufually experienced during 
 this period, was 5, the greateft heat, 98: on 
 the 25th of July 1773,^6 heat arofe to io8 Q 
 and 110; a N. E. or N. \V. wind pro- 
 duces the greateft cold, a S. or S. W. or 
 S. E. the greateft heat * . 
 
 * 6 Mem. S$av. Etrang. p. 528. 
 
 Algiers,
 
 94 Of the temper ciiur^jf Places, 
 
 Algiers, lat. 36 49', long. 2 17' E. 
 
 The temperature of Algiers was obferved 
 during 2 years by Mr. Taitebout, by means of 
 a thermometer of Reaumur imperfectly gra- 
 duated. The obfervations are recorded in the 
 Paris Memoirs for 1735, and the mean was 
 thence deduced by Mr. Wargentin ; by his 
 computation it appears to be 72 degrees. 
 
 The ftandard temperature is 
 65, the difference is 7 ; 
 though I cannot venture to 
 fay that the temperature of 
 Algiers is fo much higher 
 than that of the ftandard; yet 
 it probably is 3 or 4 degrees 
 higher, as it has the Mediter- 
 ranean, which is much warmer 
 than the ftandard, on the north, 
 and the ftill warmer tracts of 
 Barbary on its fouth * . It very 
 feldom rains here in Summer, 
 the heat ftiil more confider- 
 
 Jan. 
 
 627 
 
 Feb. 
 
 61,5 
 
 March 
 
 63,8 
 
 April 
 
 67 
 
 May 
 
 72,8 
 
 June 
 
 77>5 
 
 July 
 
 82,6 
 
 Auguft 
 
 84,3 
 
 Sept. 
 
 81,2 
 
 oaob. 
 
 775 
 
 Nov. 
 
 70,2 
 
 Pec. 
 
 63,4 
 
 which renders 
 able. 
 
 Mem. Stock. 1758. 
 
 Madeira,
 
 Between Lat. 40 and o. 
 
 95 
 
 Madeira, Funchall, lat. 32 37', long. 17. 
 
 The annual temperature, by obfervations. 
 of 4 years, was 6 8, 6; that of the ftandard 
 680,9*. 
 
 Jan. 64 1 8 
 Feb. 64,3 
 March 65,8 
 April 65,5 
 May 66,53 
 June 69,74 
 
 July 73.45 
 Auguft 75,02 
 Sept. 75,76 
 Oftob. 72,5 
 Nov. 69,08 
 Dec. 65, 
 
 Thibet, lat. 32 and 30. 
 
 This country being very diftant from the 
 fea, and formed by the union of very high 
 mountains, is exceeding cold, in fo much that 
 the thermometer in Winter is often at 3, and 
 the froft lafts until the middle of April f. 
 
 * Phil. Tranf. 1752, 
 p. 471. 
 
 and 54. f Ibid. An. 1777, 
 Grand
 
 96 Of the temperature of Places, 
 
 Grand Cairo, lat. 30, long. 31 23 E. 
 
 The only obfervations I have met with on 
 the temperature of this city, are thofe of Mr. 
 Niebur * , and thefe are very imperfect. As 
 far as I can colled: from them, the mean of 
 the year 1762 was 75,9 which is about 5 
 degrees above that of the ftandard. That it 
 mould be higher, we may eafily infer from 
 its fituation, having the Mediterranean on its 
 north, and the ftony defarts of Arabia on the 
 eaft ; but the climate is fubjed to great inequa- 
 lities, for the mean of the year 1761 was but 
 
 Meaa 
 
 Jan. 57 
 
 Greateft H< 
 
 69 
 
 Feb. 63 
 
 73 
 
 March 69 
 
 86 
 
 April 72 
 
 87 
 
 May 77 
 
 96 
 
 June 82 
 
 101 
 
 July 88 
 
 101 
 
 Auguft 87 
 
 99 
 
 October 77 } 
 
 as I fuppofe 
 
 Novem. 8 1 
 
 9 D 
 
 Decem. 66 
 
 
 Voy. Vol. I. 
 
 Canton
 
 Between Laf. 40* and o. 97 
 
 Canton, lat. 23, long. H3E. 
 
 By the accurate obfervations of Mr. Raper 
 during the year 1774, its temperature was 
 75*, 14; ftandard temperature 75,4*. 
 
 Greateft Heat, Leaft. 
 
 Jan. 6o47 - - 66,5 - 51 
 
 Feb. 67,44 
 
 March 69,5 
 
 April 74,6 
 
 May 79,82 
 
 June 82,48 
 
 July 84,84 
 
 Auguft86,n - - 89 80 
 
 Sept. 85,20 
 
 O&ob. 76,91 
 
 Nov. 71,44 
 
 Dec. 62,88 
 
 Mexico, lat. 19 54', long. looW. 
 
 This city is faid to ftand 5491 feet above 
 the level of the Pacific Ocean, midway be- 
 tween it and the Gulph of Mexico. It is 
 furrounded by mountains at the diftance of 
 about i oo miles ; its annual temperature is 
 not as yet well known, but probably differs 
 
 * MS. Journal at the Houfe of the Royal Society. 
 
 H but
 
 98 Of the Temperature of Places, 
 
 but a few degrees from that of Quito. The 
 few obfervations made here during the year 
 1 769, were made public by Pere La Cotte ; 
 they may ferve to give fome idea of this 
 climate *. 
 
 Gre*teft Heat. Leaft. 
 
 Hence it appears, that the 
 temperature of Mexico dif- 
 fers but little from that of 
 Quito. The winds are here 
 pretty conftant, and foine- 
 times impetuous, but it rains 
 very feldom. 
 
 Tivoli in St. Domingo, lat. 19*. 
 
 Its mean temperature during the year 1779 
 was 74 t- 
 
 April 74 
 May 75 
 June 72 
 July 71 
 Auguft 70 
 Sept. 70 
 Odob. 70 
 Nov. 68 
 Dec. 66 
 
 53 
 5 1 
 56 
 5 
 
 54 
 5 
 
 48 1 
 
 4 
 46 
 
 Jan. 
 
 Feb. 
 
 March 
 
 April 
 
 May 
 
 June 
 
 69 
 
 68,9 
 7-1,6 
 
 73.4 
 
 I 2 
 
 7 8,i2 
 
 77>9 
 Auguft 77,02 
 
 Sept. . 77 
 
 The ftanclard temperature is 
 78,3, but the elevation of 
 Tivoli is confiderable, as the 
 mean height of the barometer, 
 during 2 years, was 28,27 
 inches. According to the efti- 
 mation of Dr. Bla'gden, which 
 feems to me very probable, 
 the mean heat of the coaft both 
 
 / / 
 
 Meteorol. p. 337. f Mem, Societ. de Med. 1779. 
 4 
 
 of
 
 Between Lat. 40 and o. 99 
 
 74,75 of this ifland and Jamaica is 
 Nov. 73,62 nearly 8 1 * ; at Cape Francois 
 Dec. 70,92 the heat in May and June is 
 generally from 85 to 95 by 
 day, and about 80 by night j* . 
 
 Senegambia, lat. 1 6, long. 1 6 W. 
 
 The mean heat is So , the temperature of 
 the coldeft months 70 ; it feldom rifes above 
 94, or falls below 64 \ ; the ftandard tempe- 
 rature is 79,9. 
 
 Senegal, lat. 15 53,' long. i626'. 
 
 According to Adanfon, the air in the fhade 
 is moftly heated to 94 ; on the road from Se- 
 negal to Podor it is frequently at 1 1 1 by day, 
 and 86 at night; in Nigritia the fand is heated 
 to 1 40. 
 
 Manilla, lat. 14 36', long. 120058' E. 
 
 By Mr. Gentiles account, the mean tempe- 
 rature of this town, feems to be 78^4 ; tha 
 of the ftandard 80^,4 ; the cold produced by 
 evaporation, after the great rains, renders 
 many of the intertropical ifland s, fo'mewhat 
 cooler than the fea. 
 
 * Phil. Tranf. 1781, p. 337. f Mem. Par. 1770, 
 
 p. 679. % Phil. Tranf. 1780. 
 
 H 2 Jan.
 
 ioo Of the temperature of Places, 
 
 Jan. 70 
 Feb. 68 
 March 72 
 April 75 
 May 75 
 June 87 
 July 87 
 Auguft87 
 Sept. 84 
 
 oa. 84 
 
 Nov. 82 
 Dec. 70 
 
 Fort St. George, lat. 13, long. 87 E. 
 
 From the beginning of March 1777, to the 
 end of February, 1778, the temperature of 
 this coaft was upon a mean, 8i*,4; that of 
 the ftandard is 8i,3; the greateft heat was 
 102, the leaft 64. 
 
 J an - 73 
 Feb. 76,5 
 March 77 
 April 80,5 
 May 88 
 June 89,5 
 July 87 
 Auguft 86,5 
 Sept- 83,5 
 
 oa. 82 
 
 Nov. 75 
 Dec. 76,5 
 
 Ponticherry,
 
 Between Lat 40 and o. I o I 
 
 Ponticherry, lat. 12, long. 67. 
 
 The temperature of this town, as ob- 
 ferved by Mr. Coffigny, and calculated by Mr. 
 Wargentin, is 88 ; the account given of it, 
 by Mr. Gentil, agrees very well with this re- 
 fult ; it furpafies the ftandard by 7 degrees, 
 which is owing to the fands that furround it. 
 
 Mr. Gentil remarked, that 
 during the greater part of May, 
 June, July, and Auguft, the 
 heat was 113 or 115, even at 
 the height of 30 feet, in day 
 time, and 82 at night ; and 
 that in April, it was generally 
 from 88 to 93. 
 
 Jan. 
 
 
 
 797 
 
 Feb. 
 
 83 
 
 March 
 
 88 
 
 April 
 
 91,5 
 
 May 
 
 94 
 
 June 
 
 95,4 
 
 July 
 
 93,8 
 
 Aug. 
 
 92 
 
 Sept. 
 
 89,5 
 
 oa. 
 
 85 
 
 Nov. 
 
 81,2 
 
 Dec. 
 
 80,3 
 
 CHAP. XIII. 
 
 Of the ^Temperature of Places, Jituated In the 
 Southern Hemifphere. 
 
 Falkland Iflands, lat. 51, long. 66 W. 
 
 'TP H E S E iflands lie about 240 miles E. 
 of the continent of America ; their tem- 
 perature, during part of the year 1776, and 
 H 3 part
 
 102 Of the Temperature of Places, 
 
 part of 1777, was47,4*, which is 5 below 
 the ftandard ; but the deficiency occurs chiefly 
 in the Summer months. 
 
 Jan. 56 
 
 Feb. 54 
 March 5 1 ,6 1 
 
 April 48,65 
 
 May 46,64 
 
 J une 43>5 
 
 July 37,41 
 
 Here it is evident, that the 
 months of June, July, and Au- 
 guft, which anfwer to our De- 
 cember, January, and February; 
 all, except Auguft, rather 
 
 are 
 
 warmer than the correfponding 
 months atLondon. 
 
 4575 
 
 oa. 47,51 
 
 Nov. 47,2 
 Dec. 49,87 
 
 I have allowed the mean of January two ' 
 degrees more than authorized by the table, 
 as the firft 19 days, which mould be the 
 warmeft, are omitted in the Journal. 
 
 Cape of Good Hope, lat. . 33 55', lone;. 
 1 8 28' E. 
 
 During the Winter months, May, June, 
 and July ; the mean temperature feems to be 
 from 45 to 55 ; the heat fcarcely exceeds 
 64, and feldom falls fo low as 34 : in Sum- 
 mer, the thermometer is generally between 
 70 and 80, and fometimes between 80 and 
 
 Dalrymple's Voy, 
 
 90,
 
 Situated in the Southern Hemifphere. 103 
 
 90*, but fcarce ever exceeds 95 ; the S. E. 
 wind is the coldeft *. 
 
 Quito, in Peru, lat. o 13', long. 77 50' W. 
 
 According to Bouguer, this city is fituated 
 about 130 miles from the Pacific Ocean ; its 
 temperature is conftantjy from 63 to 66 ; 
 that of the ftandard is 84* ; but the elevation 
 of Quito is 9240 feet, which by the rule 
 chap. 5, lowers its annual temperature down 
 to 6 1 degrees, which probably is the true 
 mean, as Mr. Bouguer does not feem to have 
 kept a regular journal : the mean temperature 
 of the coaft is about 85, for by day, the 
 heat is from 90* to 96, and by night, from 
 
 75 to 79. 
 
 On the fummit of Pinchinca, elevated 5760 
 feet above Quito, the temperature varies 38 5 
 that is, from a few degrees under congelation, 
 at night, to 63 or 65 at mid-day, when the 
 thermometer is expofed to the fun ; but, as 
 the thermometer had, moft probably, a metal- 
 lic fcale fixed to it, we muft abate the tempe- 
 rature, at 'leaft, i o degrees j~. 
 
 * i Sparm. 113. Mem. Par. 1751. p. 447. f Bou- 
 guer Figure de la Terre. 
 
 H 4 CHAP.
 
 1 04 Obfervations and Inferences. 
 
 CHAP. XIV. 
 
 General Obfervations, and Inferences. 
 
 T N the firft place, we may obferve, that the 
 -* month of January is the coldeft in every 
 latitude. 
 
 adly. That July is the warmeft month in 
 all latitudes above 48 ; but in lower latitudes, 
 Auguft is generally the warmeft. 
 
 3dly. That December and January, and 
 alfo June and July, differ but little. In lati- 
 tudes .above 30, the months of Auguft, 
 September, October, and November, dif- 
 fer more from each other, than thofe of 
 February, March, April, and May. In lati- 
 tudes under 30, the difference is not fo great. 
 The temperature of April approaches more, 
 every where, to the annual temperature, than 
 that of any other month : whence we may 
 infer, that the effects of natural caufes, that 
 operate gradually over a large extent, do not 
 arrive at their maximum, until the activity of 
 the caufes begins to diminifh ; this appears 
 alfo in the operation of the moon on feas ? 
 which produces tides ; but after thefe effects 
 have arrived at their maximum, the decrements 
 are more rapid, than the increments origi- 
 nally were, during the progrefs to that 
 imum,
 
 Obfervattons and Inferences. 1 05 
 
 4thly. That the differences, between the 
 hotteft and coldeft months, within 20 degrees 
 of the equator, are inconfiderable, except in 
 fome peculiar fituations ; but that they increafe 
 in proportion, as we recede from the equator. 
 
 5thly. That in the higheft latitudes, we 
 often meet with a heat of 75 or 80 degrees ; 
 and particularly, in latitudes 59 and 60, the 
 heat of July is frequently greater, than in 
 latitude 51. 
 
 6thly. That every habitable latitude enjoys 
 a heat of 60 degrees at leaft, for two months ; 
 which heat feems neceffary, for the growth 
 and maturity of corn. The quicknefs of vege- 
 tation in the higher latitudes, proceeds from 
 the duration of the fun over the horizon. 
 Rain is little wanted, as the earth is fufficiently 
 moiftened by the liquefaction of the fnow, that 
 covers it during the Winter ; in all this, we 
 cannot fufficiently admire the wife difpofition 
 of Providence. 
 
 ythly. It is owing to the fame provident 
 hand, that the globe of the earth is interfered 
 with feas and mountains, in a manner, that 
 on its firft appearance, feems altogether irregu- 
 lar and fortuitous ; ' prefenting to the eye of 
 ignorance, the view of an immenfe ruin : but 
 when the effects of thefe feeming irregularities, 
 on the face of the globe, are carefully infpecl:- 
 ed, they are found moft beneficial, and even 
 neceffary to the welfare of its inhabitants ; for, 
 to fay nothing of the advantages of trade and 
 
 commerce,
 
 1 06 Qbfervations and Inferences. 
 
 commerce, which could not exift without 
 thefe feas ; we have feen, that it is by their 
 vicinity, that the cold of the higher latitudes 
 is moderated, and the heat of the lower. It 
 is by, the want of feas, that the interior parts 
 of Afia, as Siberia and Great Tartary, as 
 well as thofe of Africa, are rendered almoft 
 uninhabitable ; a circumftance which fur- 
 nifhes a ftrong prejudice againft the opinion 
 of thofe, who think thefe countries w r ere the 
 original habitations of man. In the fame man- 
 ner, mountains are neceflary ; not only as the 
 refervoirs of rivers, but as a defence againft 
 the violence of heat, in the warm latitudes : 
 without the Alps, Pyrenees, Apennine, the 
 mountains of Dauphine, and Auvergne, &c. 
 Italy, Spain, and France would be deprived of_ 
 the mild temperature, they at prefent enjoy. 
 Withoutlhe Balgate hills, or Indian Apennine, 
 India would have been a defart. Hence, Ja- 
 maica, St. Domingo, Sumatra, and moft other 
 intertropical iilands, are furnifhed with moun- 
 tains, from which the breezes proceed that 
 refrefh them. 
 
 Sthly. We may obferve, why grapes do 
 not come to perfection in the neighbourhood 
 of London, as they do in that of Paris, 
 though the annual heat be nearly the fame, and 
 the Winters are rather milder at London ; for 
 by the tables of the monthly temperatures of 
 both, we find, that from the beginning of April, 
 to the end of Odober, the heat is greater at 
 
 Paris j
 
 Of the Caufes of unufaal Cold, &c. 107 
 
 Paris ; and thus we may learn the fitnefs of 
 any climate, for any vegetable : hence we fee, 
 that vines may thrive, as they actually do, at 
 Aftracan *. 
 
 Laftly. Since the aftronomical fource of 
 heat is permanent, and the local caufes of its 
 modification undergo no annual variation, 
 and yet the temperature of no two fucceeding 
 years, is perfectly alike, it is evident, that 
 this annual variation proceeds from caufes 
 equally variable : of theie, there may be many, 
 but at prefent, we know of none, that have a 
 demonstrable influence on the weather, but 
 winds; and fmce winds themfelves, however 
 uncertain in appearance, are like all the 
 other phenomena of nature, governed by 
 fixed and determinate laws, they deferve the 
 moft ferious investigation, for which we are 
 at prefent, tolerably well prepared. 
 
 CHAP. XV. 
 
 Of the Caufes of unufual Cold in Europe. 
 
 "TNUSUAL cold happens either in the Sum- 
 mer, or in the Winter feafon ; the cir- 
 cumftances, which render Summers lefs warm 
 than ufual, are pretty obvious ; for the dimi- 
 
 * 2 Decouvertes Ruffes, p. in. 
 
 nution
 
 icS Of the Caufes of unufual Cold, &c. 
 
 nution of heat may arife, either from a 
 long continuance of eafterly or northerly 
 winds, or from frequent and heavy rains, 
 which are followed by great evaporation, or 
 from a long continuation of cloudy weather, 
 in the months of June and July, which pre- 
 vents the earth from receiving its proper de- 
 gree of heat. 
 
 But the caufes of unufual cold in winter, 
 are more remote, and of more difficult invef- 
 tigation ; thofe that I am acquainted with are, 
 
 i ft. Unufual cold In the preceding Summer. 
 For, as the Winter's heat is in great mea- 
 fure derived from the earth ; if this be de- 
 prived of its ufual ftore of heat, the want of 
 it, muft be perceived the enfuing Winter ; 
 the cold of Jan. 1 709, was the fevereft, long v 
 known in Europe; and Mr. Derham remarked, 
 that the preceding June was fo cold, that his 
 thermometer was near the freezing point, on 
 the 1 2th of that month, and the quantity of 
 rain much greater than ufual. * Mr. Wolf 
 made the fame obfervation, at Halles, in Ger- 
 many f. 
 
 2dly. Heaiy rams followed by eajlerly or 
 northerly 'winds. This circumftance would 
 produce great cold in any feafon, on account 
 of the powerful evaporation, promoted by 
 thefe dry winds ; it actually took place, in 
 
 * Pbyf. Theol. Lib. I. cap. 3. f Meletemeta, p. 356. 
 
 Odober,
 
 Of the Caufes of unufual Cold, &c. 1 09 
 
 October, 1708, as Mr. Wolf obferved ; and 
 an intenfe cold immediately followed *. 
 
 3dly. Wejlerly or foutherly currents, in the 
 upper regions of the atmofphere, while eajlerly or 
 northerly prevail in the lower. For the warm 
 currents are in great meafure deprived of their 
 moifture, by the cold of the fuperior regions ; 
 and, this defcending in the form of fnow, 
 cools the inferior ftrata, below their ufual 
 temperature : this circumftance alfo took place 
 in the year 1 709, as Mr. Wolf remarks, when 
 the cold was greateft f. Yet I have often 
 remarked, the weather to become milder after 
 a fall of fnow ; but this happens, chiefly when 
 the wind is weft or fouth ; for the vapours 
 being then in the lower atmofphere, warm it 
 by their condenfation. 
 
 4thly. ^The arrival of Siberian, or American 
 winds. Siberia is 2800 miles to the eaft of 
 London ; but, according to the computation 
 of Mr. Smeaton, a common high wind moves 
 at the rate of 35 miles an hour ; and, there- 
 fore, may pafs to us in three days, from Sibe- 
 ria : now Dr. Blagden has fhewn, that a cur- 
 rent of 20 leagues in breadth, and 10 degrees 
 warmer than the ocean, through which it 
 flows, may preferve four degrees of its heat, 
 after it has traverfed a fpace of 7 or 800 
 miles f; and Sir Benjamin Thomfon has 
 
 * Meletemeta, 326. f Ibid. 357. % Phil. 
 
 Tranf. 1781. 
 
 proved,
 
 no Of the Caufes of unufual Cold, &c. 
 
 proved, that air is much a worfe conductor 
 of heat, than water *; therefore, we may well 
 fuppofe, that the Siberian winds may preferve 
 much of their original temperature, on ar- 
 riving here ; particularly if they blow with 
 considerable force, and laft fome days. Ame- 
 rica is not fo diftant, but wefterly winds 
 may arrive from it, in a few days : it is true, 
 their rigour is much moderated, by pairing 
 over the fea ; but if the furface of the fea had 
 been previoufly cooled by northerly winds ; 
 or, if the wefterly are flrong, and of long 
 continuance, they may prove unufually cold 
 in this country. Mr. Derham, on comparing 
 his journals with thofe of Mr. Robie, in New 
 England, found, that after a few days, the 
 American winds actually paffed into Englandf. 
 The Winter of 1784 was equally fevere, in 
 America, as in Europe J. It mould alfo be 
 remarked, that the Siberian winds, if they 
 originate in a lower latitude, will appear S. E. 
 to us ; becaufe, rinding the atmofphere of lati- 
 tudes more northern, lefs cold, they will blow 
 towards that quarter alfo ; and if they origi- 
 nate in a latitude, higher than ours, they will 
 appear N. E. as they will be deflected to more 
 fouthern latitudes, where they meet with lefs 
 refiftance ; and for the fame reafon, the Ame- 
 rican winds will appear N. W. or S. W. 
 
 * Phil. Tranf. 1786. f 6 Phil. Tranf. Abridg. Part 
 2. p. 143. J 25 Roz. 465. 
 
 5thly.
 
 Compari/on of the "Temperature^ &c 1 1 1 
 
 5thly. 'fhe fall of a f up en or ftratum of tlx 
 atmofphere. This will happen, when a cold 
 wind, in the upper regions of the atmofphere, 
 paries over a country, the lower ftrata of 
 whofe atmofphere, are fpecifically lighter ; 
 and hence a low ftate of the barometer, gene- 
 rally precedes fuch extraordinary cold. It is 
 probably, for this reafon, that Holland oftener 
 experiences a degree of cold, greater than 
 countries, placed under higher latitudes; for 
 Holland being a very moift country, its at- 
 mofphere abounds more in vapours, which 
 render it fpecifically lighter ; thus, during the 
 great cold of Jan. 1783, the barometer was 
 lower, than it was known to be for 50 years 
 before, during that month *: and Mufchen- 
 brock remarked, that in Winter, when the 
 mercury in the barometer defcends, the cold 
 increafes +. 
 
 CHAP. XVI. 
 
 Companfon of the ^Temperature of London^ 'with 
 that of other noted Places. 
 
 THE firft column exhibits the differences 
 of the annual temperature ; the fecond, 
 that of the month of January, as being ge- 
 nerally the coldeft; and the third, that of 
 
 * 25 Roz. 463. Mem. Berlin, 1782, p. 25. f Muf- 
 chenb, p. 120. . MMLXX.
 
 H2 
 
 Comparison of the temperature^ 
 
 July ; that of London, as the ftandard, being 
 eftimated at 1000. The degree of cold, is 
 eftimated in the lecond column ; and the de- 
 gree of heat, in the firft and third. 
 
 Annual. Jan. July. 
 
 London 
 
 1000 
 
 1000 
 
 1000 
 
 Paris - - 
 
 1028 
 
 1040 
 
 I0 37 
 
 Edinburgh - 
 
 9 2 3 
 
 1040 
 
 914 
 
 Berlin - - 
 
 942 
 
 
 
 Stockholm - 
 
 811 
 
 1583 
 
 964 
 
 Peterfburgh - 
 
 746 
 
 359 
 
 1008 
 
 Vienna - - 
 
 987 
 
 1305 
 
 1037 
 
 Pekin - - 
 
 1067 
 
 1730 
 
 1283 
 
 Bourdeaux - 
 
 1090 
 
 9 2 5 
 
 "39 
 
 Montpelier - 
 
 1170 
 
 850 
 
 1196 
 
 Madeira - - 
 
 1319 
 
 559 
 
 1128 
 
 Spanifh Town, 
 
 
 
 
 in Jamaica - 
 
 1557 
 
 
 
 Madrafs - 
 
 
 491 
 
 1349 
 
 FINIS.
 
 ( "3 ) 
 
 A View of the annual Temperature of the dif- 
 ferent Places mentioned in this Ejflay 9 accord- 
 ing to the Order of their Latitudes. 
 
 
 North 
 
 
 Mea. 
 
 
 Lat. 
 
 Longitude. 
 
 Annual 
 
 
 deg. m. 
 
 deg. m. 
 
 Heat. 
 
 Wadfo, in Lapland, 
 
 7Q5' 
 
 
 36 
 
 Abo, 
 
 60,27 
 
 22,18 E. 
 
 4) 
 
 Peterfburgh, 
 
 59'5^ 
 
 30,24 E. 
 
 38 1 
 
 Upfal, 
 
 59>5i 
 
 '7.47 i: - 
 
 41,88 
 
 Stockholm, 
 
 9,20 
 
 1 8, E. 
 
 4-2,39 
 
 Solyflcamfki, 
 
 59> 
 
 54, E. 
 
 3 6 >2 
 
 Edinburgh, 
 
 55,57 
 
 3> W. 
 
 i-7,7 
 
 Francker, 
 
 53, 
 
 5,42 E. 
 
 52,6 
 
 Berlin, 
 
 52,32 
 
 i3,3i E. 
 
 4$ 
 
 Lyndon, in Rutland, 
 
 52,3 r 
 
 o, 3 W. 
 
 48,03 
 
 Leyden, 
 
 52,10 
 
 4,32 E. 
 
 52,25 
 
 London, 
 
 5i,3 J 
 
 
 5J,9 
 
 Dunkirk, 
 
 51,0- 
 
 2, 7 E. 
 
 54,9 
 
 Manheim, 
 
 49^7 
 
 9, 2 E. 
 
 5i,5 
 
 Rouen, 
 
 4-9,26 
 
 i, W. 
 
 5i, 
 
 Ratifbon, 
 
 48,56 
 
 12,05 E. 
 
 49,35 
 
 Paris, 
 
 48,5- 
 
 2,25 E. 
 
 52, 
 
 Troyes, in Champaigne, 
 
 48,18 
 
 4,10 E. 
 
 33,17 
 
 Vienna, - - . 
 
 4&,i2 
 
 16,22 E. 
 
 5i,53 
 
 Dijon, - . 
 Nantes, 
 
 47> J 9 
 47,13 
 
 4,57 E - 
 1,28 E. 
 
 52,8 
 55,53 
 
 Poitiers, - - 
 
 46,39 
 
 i *J S 
 
 0,30 E. 
 
 53,8 
 
 Laufanne, 
 
 46>3i 
 
 6,50 E. 
 
 48,87 
 
 Padua, 
 
 45,23 
 
 12, E. 
 
 52,2 
 
 Rhodez, in Guienne, . 
 
 45,21 
 
 2,39 E - 
 
 52,9 
 
 Bordeaux, 
 
 44^0 
 
 0,36 W. 
 
 57,6 
 
 Montpelier, 
 
 43'3^ 
 
 3.73 E - 
 
 60,87 
 
 Marfeilles, 
 
 43> J 9 
 
 5,27 E. 
 
 61,8 
 
 Mont Louis, in Roufillon, 
 
 42> 
 
 2,40 E. 
 
 44,5 
 
 Cambridge, in New England, 
 Philadelphia, 
 
 42,25 
 39>5 
 
 71, W. 
 75,09 W. 
 
 5o,3 
 52,5 
 
 Pekin, 
 
 39^54 
 
 116,29 W. 
 
 55,5 
 
 Algiers, 
 
 36>49 
 
 2,17 E. 
 
 72, 
 
 Grand Cairo, 
 
 30> 
 
 31,23 E. 
 
 73, 
 
 Canton,
 
 ( 4 ) 
 
 Canton, 
 
 Tivoli, in St. Domingo, 
 
 Spanifh Town, in Jamaica, 
 
 Manilla, 
 
 Fort St. George, 
 
 Ponticherry, 
 
 Falkland Iflands, 
 Quito,. * 
 
 North 
 Lat. 
 deg. m. 
 
 Longitude, 
 deg. m. 
 
 Metm 
 
 Annual 
 Heat. 
 
 2 3> 
 
 113, E. 
 
 75>H 
 
 ro,, 
 
 
 745 
 
 18,15 
 
 76,38 W. 
 120,58 E. 
 
 Si, 
 8i' 4 
 
 12, 
 
 67,' E.' 
 
 88^ 
 
 South 
 
 
 
 Lat. 
 
 
 
 
 66, W. 
 
 47,4 
 
 W 
 
 77,50 W. 
 
 62, 
 
 ERRATA. 
 
 P. 18, line 13, for 62,1, read 62. 
 P. 1 8, line 21 and 23, for 62,1, read 62. ' 
 P. 20, line 7) for fun's altitude, read fun's 
 mean altitude.
 
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