20 UNIFORM TEMPERATURE 



We know that the rapidity of cooling increases 

 with the difference between the temperature of the 

 heated body and that of the surrounding medium ; 

 that is, the colder the surrounding medium the 

 shorter the time required for the cooling of the 

 heated body. 



How unequal, then, must be the loss of heat in a 

 man at Palermo, where the external temperature 

 is nearly equal to that of the body, and in the polar 

 regions, where the external temperature is from 70° 

 to 90° lower. 



Yet, notwithstanding this extremely unequal loss 

 of heat, experience has shewn that the blood of the 

 inhabitant of the arctic circle has a temperature as 

 high as that of the native of the south, who lives in 

 so different a medium. 



This fact, when its true significance is perceived, 

 proves that the heat given off to the surrounding 

 medium is restored within the body with great 

 rapidity. This compensation takes place more ra- 

 pidly in winter than in summer, at the pole than at 

 the equator. 



Now, in different climates the quantity of oxygen 

 introduced into the system of respiration, as has 

 been already shewn, varies according to the tempe- 

 rature of the external air ; the quantity of inspired 

 oxygen increases with the loss of heat by external 

 cooling, and the quantity of carbon or hydrogen 

 necessary to combine with this oxygen must be 

 increased in the same ratio. 



