252 ANIMAL HEAT. 



maintaining an uniform temperature have had reference to 

 the ordinary ease of man living in a medium colder than 

 his body, and therefore losing heat both by radiation and 

 evaporation. The losses in these two ways will bear, in 

 general, an inverse proportion to one another ; the small 

 loss of heat by evaporation in cold climates may go far 

 to compensate for the greater loss by radiation ; as, on 

 the other hand, the great amount of fluid evaporated in 

 hot air may remove nearly as much heat as is commonly 

 lost by both radiation and evaporation in ordinary tem- 

 peratures. Thus, it is possible, that the quantities of 

 heat required for the maintenance of an uniform proper 

 temperature in various climates and seasons are not 

 so different as they may at first thought seem : but 

 on these points no accurate information has yet been 

 obtained. 



Neither, as to the maintenance of the temperature of the 

 body in hot air is much more known, than that great heat 

 can for a time be borne with little change in the proper 

 temperature of the body, provided the air be dry. Sir 

 Charles Blagden and others supported a temperature 

 varying between 198 and 211 F. in dry air for several 

 minutes; and in a subsequent experiment he remained 

 eight minutes in a temperature of 260. Delaroche and 

 Berger observed that the temperature of rabbits was 

 raised only a few degrees when they were exposed to 

 heat varying from 122 to 194. But such heats are not 

 tolerable when the air is moist as well as hot, so as to pre- 

 vent evaporation from the body. M. C. James states, that 

 in the vapour baths of Nero he was almost suffocated in a 

 temperature of 1 1 2, while in the caves of Testaccio, in 

 which the air is dry, he was but little incommoded by a 

 temperature of 176. In the former, evaporation from 

 the skin was impossible ; in the latter, it was, probably, 

 abundant, and the layer of vapour which would rise from 

 all the surface of the body would, by its very slowly con- 



