TEMPERATURE. 



this hzlr was prefentcd to the Mufoiim of Natural Hiftory 

 ill Paris. It coiilifts of three dillinft kinds. The one is 

 fliff black, briftles, a foot or more in length ; another kind 

 is a coarfe flexible hair, of a reddilh-brown colour ; the 

 third kind is a coarfe wool, whicl\ grow among the roots 

 of the lonj hair. Thcfe afford undeniable proof, that this 

 animal belonged to a race of elephants inhabiting a cold 

 region, and was not fitted to dwell in the torrid zone. This 

 animal was a male, and had a long mane on its neck. The 

 bones were all perfect. As the only proof offered for the 

 refrigeration of the earth was tlie former exillcnce of tro- 

 pical animals in northern latitudes, and as this can no 

 longer be maintained, we have reafon to believe that the 

 general temperature of the globe is llationary, though the 

 chmate of particular countries may vary at different periods, 

 from cultivation, the dcftrudion of large forclls, or other 

 local caufes. 



Though the annual changes in the temperature of the 

 climate affeft the furface only to a fmall comparative depth, 

 yet the continued effeft of the annual mean temperature, 

 confidered as a permanent caufe, may be fufficient to keep 

 the internal temperature of the earth tlationary, in each 

 latitude, at a ftill greater depth. Hence we find that the 

 internal temperature of the earth, and the mean temperature 

 of the atmofphere, are nearly, but not exaftly, the fame ; 

 for in all northern countries, the mean temperature of the 

 earth is higher than that of the air, and the difference, ac- 

 cording to the obfervations of Dr. Wahlenberg, fellow of 

 the Royal Society of Stockholm, appears to incieafe as we 

 advance northward, or as the cold of the winter becomes 

 mora fevere. This would alfo feem to give additional con- 

 firmation to the opinion, that there is a permanent fource of 

 heat within the globe itfelf. The following table fhews the 

 rate at which the temperature varies according to the latitude. 



The obfervations were made on fprings which threw up 

 a large quantity of water at a permanent degree of tem- 

 perature in all feafons. It is to be regretted that wc have 

 not a feries of obfervations made with equal care in fouthern 

 latitudes. M. Volney dates, in his " Travels in America," 

 that the mean temperature of wells forty-five feet deep was 

 as under : 



Charleftown 



Virginia 



Philadelphia 



Maffachufetts 



Vermont 



Fahr. 

 63° 

 57 

 53 

 49 

 44 



This depth is too fmall, to give the true mean temperature 

 of the earth ; and the obfervations can only be regarded as 

 approximation! to the truth. On the fame authority it is 

 flated, that the temperature of the earth, to a confiderable 

 depth under the torrid zone, is 14° Reaumur, or 63° 

 Fahrenheit. 



In the fouthern parts of England, the mean temperature, 

 taken from permanent fprings, is about 48° ; at Edinburgh, 

 ^fi ir. the north of Ireland, 48° ; and at Paris, 51 ^ 



For the temperature of the atmofphere, fee Atmosphere, 

 where the mean temperature in different latitudes is given. 

 Mr. Humboldt has lately publiihed a botanical account of 

 the new genera and fpecies of plants difcovered in the 

 tropical regions of America, with many intereiling obferva- 

 tions on the temperature, as affefting the growth of plants. 

 The plants of the torrid zone extend farther through the 

 fouthern temperate zone than through the northern, owing^ 

 to the greater influence of the ocean in the fouthern hemi- 

 fphere, in moderating the rigour of winter ; the ocean bear- 

 ing a much greater proportion to the furface on the fouth, 

 than on the north iide of the equator. In eftimating the^ 

 climate fuited for the growth of particular plants, the mean 

 temperature will not afford a correft ftandard ; for though 

 the mean temperature of the year, in the middle latitudes of 

 North America, be the fame as it is in Europe, 7° further 

 north, the temperature of different feafons in thefe fame 

 latitudes by no means agrees. The winters are colder, and 

 the fummers hotter, in North America than in Europe, In 

 Philadelphia the fummer is as hot as at Rome or Mont- 

 pellier, while the winter correfponds with that at Vienn*. 

 At Quebec the fummer is warmer than at Paris, but tlip 

 winter colder than at St. Peterlhurgh. In the north of 

 China there is a ftill greater difference beiweea the heat and 

 cold, than in North America. 



In North America, as fai- as latitude 48°, the fummer* 

 are four centigrade degrees, or about 7° Fahrenheit, hotter 

 than in the correfponding latitude in Europe. Between the 

 tropics, the mean annual temperature is the fame as on tire- 

 old continent, which may be feen in the following table, 

 expreffed in degrees of the centigrade thermometer. 



OIJ Ctnthient. 



Nciu Continent, 



27.7" 

 27.5 

 25.6 

 25.6 



Senegambia 26.5" Cumana 



Madras 26.9 Antilles 



Batavia 25.2 Vera Cruz 



Mantilla 25.6 Havannah 



Twenty-five degrees correfpond with feventy-feven (fe» 

 grees of Fahrenheit. 



Though the plants of the torrid zone extend farther 

 through the fouthern temperate zone than through the 

 northern, as we have before ftated ; yet to a certain diilance 

 from the line, the temperature appears to be lefs on the fouth 

 than on the north fide. Rio Janeiro and Havannah are 

 nearly at the fame diftance from the equator ; but the mean 

 temperature of the fummer and winter months in each is 

 as under : 



Havannah. 

 December 22.1° 

 January 21.2 



July 28.5 



Auguft 28.8 



Rio Janeiro. 



June 20.0° 



July 21.2 



January 26.2 



February 27.0 



On the coaft of Peru, the temperature is diminifhed by 

 the perpetual cloudinefs of the fky, and by a ftrong fea 

 current fctting in from Cape Horn. From the tropic to 

 34° of fouth latitude, the mean temperature of the fouthern 

 hemifphere fcarcely differs from that of the northern. Be- 

 tween latitude 34° and 57°, there is a greater difference 

 between the temperatures of fummer than of winter : the 

 winters in the fouthern hemifphere are not colder, but the 

 fummers are confiderably more fo than in the northern hemi- 

 fphere. In fouth latitude 48^, the fummer temperature is 

 the fame as the winter temperature of Toulon, Cadiz, and 

 Rome. 



The higher we afcend above the level of tlie fea, and the 

 farther we advance from the equator, the greater is the dif. 



ference 



