COOLING OF ANIMALS EXPOSED TO GREAT HEAT. 365 



In a stove I exposed to a mean temperature of 45*^ Experiments 

 [113" F,] a rabbit, the temperature of which before the °" "" '^^'^'' 

 experiment was 39'7^ [103'46* F.j. After remaining there 

 an hour and forty minutes, it had acquired a temperature 

 of 43*8 [110-84° F.]. A frog, exposed in the samestove and two frogs. 

 to a similar heat, acquired in one hour a temperature of 

 ^e-T" [80-06° F,] ; which it preserved during the rest of 

 the time it remained in the stove, being half an hour. The 

 temperature of another frog, exposed to a mean heat of 

 46-2° [IIS-IG*^ F.], rose to 28* [82-4« F.], at which it 

 became stationary. 



They who have imacined, that there was no necessary Some have sup- 



. . , . . . , . , ^. Pos«' the cold 



connection between the cause of animal heat, and that or produced by 

 the cold sometimes produced in the animals, havesupposed, evaporation. 

 that the latter might be occasioned hy the evaporation that 

 takes place, either at the surface of the body, or in the 

 lungs ; thus comparing this phenomena with the cooling 

 of inanimate bodies, the surface of whicli is wet. For 

 this ingenious comparison we are indebted to Frr.nklin; 

 but is it just? The only experiments made till lately, with This contradict- 

 a view to solve this question, those of Sir C. Blagden and ptSiente^ ^^' 

 his coadjutors, and those of Dr. Crawford, seem to in- 

 dicate, that it is not. Those I made myself a few years confirmed by 

 ago, and of which I have given an account in the thesis "'"^'^^• 

 already quoted, led me, on the contrary, to adopt the sup- 

 position of Dr, Franklin; though they did not allow me to 

 form a decisive opinion. I have since attempted some new- 

 ones, which, confirn)ing the results I had before obtained, 

 appear to me calculated to remove all doubts on the subject. 

 Of these I shall give the results preceded by a brief account 

 of those I formerly published. 



The principal object of the latter was to ascertain theTheinsuffi- 

 validity of the objection commonly made to Franklin's cau"e haf beln 

 theory, that the cooling produced by evaporation is insuf- alleged, 

 ticient, to explain the difference observed between the tem- 

 perature of animals exposed to a high degree of heat and 

 that of the surrounding medium. To determine this it was 

 sufficient, to examine the comparative influence of heat on 

 the temperature of animals, and on that of inanimate sub- 

 stances wetted all over. For this purpose I exposed at the Comparative 

 1 «r«P experiments. 



