ATM 



fc(r!-7 edimatcd at loco. The degree of cold is eftimated 

 IH' t;ie fecand column, and die degree of heat in the I5:ll and 

 tlurd. 



ATM 



A Fievj of ihe Annual Temperature nf d'if-rent Places, 

 accardin;^ to the Order of ihe'ir LaUtiuln. 



'■/adfo, in Lapland 

 Abo 



Pctcifburgh 

 Uplal - . 



Stockholm 

 Solyikair.il<i 

 Edinburgh 

 Franckci- 

 Beiiin 



LyndoHj in R.utland 

 Leyden 

 London 

 Dunkirk 

 Ivl;;nheim 

 Rouen 

 R^atilljon 

 [-"aris 



Troyes, in Champaigiie 

 Vienna 

 Dijon 

 Nantes 

 Poitiers 

 .Laufanne 

 Padua 



Rhodez, in Guicnnc 

 Bourdcaux 

 Montpclicr 

 Marfeilles 



Mont Louis, in Roufillon, 

 Cambridge, in New Eng- \ 

 land - . i 



Philadelphia 

 Pekin 

 Algiers 

 Grand Cairo 

 Canton 



Tivoii, in St. Domingo 

 Spanilh Town, in Jamaica 

 Manilla 



Fort St. George 

 Ponticherry 



Falkland Iflands 

 Qiiito 



North 

 L»t. 



70° 5' 

 ' 60 27 



59 56 



5; I' 

 ■ ; -'- 

 >9 



i ^S SI 



I 53 



I 52 32 



52 30 

 52 10 



I51 3' : 



51 02 ^ 



49 27! 

 49 26 

 48 56 

 48 50 

 48 18 

 48 12 

 47 19 

 47 13 

 ¥> 39 

 46 31 



45 23 

 45 21 

 44 50 

 43 36 

 43 19 

 42 



42 25 



39 56 

 39 54 

 315 49 

 30 



,23 



I IQ 

 18 15 



14 36 



13 

 I 2 



South 

 Lat. 



51° 



o 13 J 



Longitude, 



22°l8'E. 

 30 24E. 

 '7. 47E. 

 Ki E. 

 54 E. 

 W. 

 42 E. 



31 E. 

 3W. 



32 E. 



'5 



o 



4 



9 



I 



2 



4 

 16 



4 

 I 

 o 

 6 

 12 

 2 

 o 

 3 

 5 

 2 



75 



116 



2 



31 

 113 



2E. 

 W. 

 05 E. 

 25 E. 

 10 E. 

 22 E. 

 57 E. 



28 E. 

 30 E. 

 50 E. 



E. 



39 E. 

 36 W. 

 73 E. 

 27 E. 



40 E. 



W. 



09 W. 



29 w. 

 -17 E. 



230:. 

 E. 



76 38 W. 

 129 58 E. 



87 E. 

 67 E. 



66 W. 



77 50 W. 



40 



38.8 



41.88 



42.39 

 36.2 



47-7 

 52.6 



49 • 



48.03' 



52.25 



5? -9 



54-9 



S^-S 



5-1 



49-35 



52 



53- '7 



51-53 



52.8 



55-53 



53-^ 

 48.87 



52.3 

 52.9 

 57.6 



60.87 

 61.8 



44-5 



50-3 



52-5 



55-5 



72 



73 



75-14 



74 

 Si 



78.4 

 8t.3 



88 



47-4 



62 



. As the earth is the chief fource of heat in the ambient 

 atmolphere, dillance from the earth is a fouvce of cold ; 

 and the grtateft cold mull prevail in the highcit regions of 

 the atraofphere, more efpecially as clear unclouded airfeenis 

 tij receive no heat from the rays of tlie fun, whether direft 

 or refleiled. Thus, if the focus of the moll powerful 

 burning glafs be direfted on mere air, it does not produce 

 the fraallell degree of heat, becaufe the air being tranfpa- 

 reiit, a free paffage is afforded to the fun's rays. At the 

 level of the fea, the temperature correfponds to that of the 

 llandard ocean ; but as we afcend above that level, the tem- 



psrature is gradually diminifhed; but at a certain height 

 \vc arrive at the region of perpetual congelation, called by 

 M. Bouguer " the lower term of congelation." Tlie heisht 



of this varies according to the latitude of tli^ 



_ , „ ;ie ciunat',-, and 



at that height it conilantly freezes at night in evcrj- f.afon. 

 At the equator it -is at its Liglitll clev:^j.ion ; and it dcfcend* 

 towards the earth as we advance 'towards the poles. On 

 the fumniit of Pinchiiica, one of the Cordclicrc , • .ly 



under the line, M. Bonguer found the cold t m 



7 to 9 degrees below the freezing point every ir.or;.!. g be- 

 fore fun-rife. He fixes the height of " the lower te.m of 

 congelation," between the tropics, at an elevation of 15,577 

 feet ; but in lat. 28^ he thinks that it (hould commence, ia 

 fummcr, at tlie height of 13,440 feet from the level of the 

 fea. At ftill greater heights it never freezes, not bccaufc 

 the cold decrtafes, but becaufe vapours do not afcend fo 

 high : this height is called by M. Bouguer, " the upper ternt 

 of congelation," and he fixes it under the equator at the 

 height of 28,000 feet at moft. Mr. Kirwan thinks it of 

 importance to adjud the height of both thefe terms. To 

 this purpofe, he obfers'es, that under the equator the height 

 of both is nearly conllant -, but under otiier latitudes it is 

 variable both in fummer and winter, according to the di;^'rce 

 of heat which prevails on the furface of the earth. But as 

 there is a mean annual temperature pecuhar 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 conge- 

 lation, it is evident that whatever proportion the difference 

 under the equator bears to the height of cither of the 

 above terms, the fame proportion will the difference pecu- 

 har to every other latitude bear to the height of thofe 

 terms. Thus, the mean heat of the equator being 84, the 

 dilFerence 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 : : 40.3 : 12072. In this raannec 

 Mr. Kirwan calculated the foUowin;r table. 



In this manner, the height of both terms of congelation 

 may be calculated in every latitude for every degree of heat 

 obferved at the furface of the earth, on which it evidettlv 

 depends; for when that is at 32'^, the lower line of con- 

 gelation mull; be alio on the furface. Hence if the height 

 of the lower term of congelation in any latitude be known, 

 and alfo the general temperature at the furtace of the earth, 

 the decrement of heat at any lower height may be found. 

 The heat is obferved to decrcafe in afceiiding into the at- 

 mofphere nearly in an arithmetical progreliion: and thus, 

 having the firll and lal't terms, if we make fo many teni.s in the 

 progreffion as there are hnnvkeds effect in the diilancc of the 

 line of congelation, \vc ihall be able to dticraiiae the decre- 

 K k 2 meat 



