' ^72 COOLING OF ANIMALS EXPOSED TO GREAT HEAT. 



producing cold was annihilated in them, and consequently 

 that this faculty is essentially dependent on cTaporation. 

 It is true, that the heat, to M?hlch these animals were exposed, 

 did not exceed their natural temperature by two degrees 

 [a-G" F.] ; and it might be supposed, that the faculty of 

 producing cold would have been displayed by them athigher 



Tb^jr could not temperatures. But this objection will vanish, if we con. 



have borne a jj ^■^^^^ ^j^.^^j^ vvould havc been the necessary consequence 



higher heat ' . 



long. of their exposure for a time of any continuance to a moist 



heat, greater than that to which I subjected them, and con- 

 sequently that this faculty would have been extinguished in 

 them. In fact, however low the heat they endured in these 

 experiments may appear to have been, they were always 

 more or less exhausted by it; and when it was greater, 

 they appeared dying on my taking them out of the appa- 



It killed some, ratus. The guinea pig, though very lively in the morning, 

 died in the evening after experiment 10, I had likewise 

 a rabbit and a pigeon that died after similar experiments, 

 the results of which arc not ipscrted in the table. 



Why did the It may be asked perhaps, why the tcmperatiii'e of these 



animals did not merely rise to an equilibrium with the sur- 

 rounding fluid, instead of exceeding it by some degrees. 

 The answer to this question is very simple. The exercise of 

 their functions not having been disturbed, the cause, what- 

 ever it is, that produces animal heat, must havc continued 

 to act on them, and occasion this rise of temperature. It 

 is more difficult to conceive, why this rise was not greater; 

 ^iud why the same cause, which in low temperatures keeps 

 animals at 20^, 40% or even 80° [36°, 72°, or 144° F.] 

 above that of the surrounding air, does not rise more than 

 3° or 4" [5-4* or 7-2* F.], when they arc exposed to 

 heat*. This question cannot be solved, till we have a sa- 

 tisfactory answer to another of great importance, that has 

 teen often debated ; " what is the cause of ^.nimal heat?" 



* Fresh experiments that I have made since this paper was read 

 to the Institute, and which I shall soon make public, lead me to 

 think that evaporation was not entirely suppressed in those I have 

 here related: but these results instead of invahd'ating what I have 

 advanced, tend rather to coufv/m them. 



a question 



heat of the ani 

 mali increase, 



