56 APPLIED PHYSIOLOGY 



of sweat by evaporation in less than an hour. That 

 complete cessation of evaporation can induce a rise of 

 temperature there can be little doubt. In belladonna- 

 poisoning, for example, in which sweat secretion is 

 entirely arrested, the temperature may rise to 104 F. 



These various modes of heat loss present a different 

 degree of activity in different individuals. In tall thin 

 persons, for example, who have a large body surface, 

 radiation and conduction are very active, and evapora- 

 tion plays but a minor part. In short stout individuals, 

 on the other hand, who have a relatively small surface 

 and a bad power of conduction, the loss of heat by the 

 evaporation of sweat is much more often called for. 



(b) Artificial Regulation of Heat Loss. 



By the invention of clothes man has enormously 

 increased his power of withstanding cold. Thanks to 

 them, we live and move in a nearly constant atmosphere 

 of 91 F.,* whilst a naked man would have great 

 difficulty in maintaining his temperature at the normal 

 level if that of the surrounding air were even as high 

 as 80 F. 



Locke I quotes with approval the answer given by the 

 Scythian philosopher to the Athenian who wondered 

 how he could go naked in frost and snow. ' How,' said 

 the Scythian, ' can you endure your face exposed to the 

 sharp winter air?' 'My face is used to it,' said the 

 Athenian. ' Think me all face,' replied the Scythian. 



* Rubner, working with a thermopile, has shown that, if the 

 radiation of heat from the naked skin be taken as 100, with a vest 

 on it is 73 ; shirt and vest, 60 ; waistcoat, shirt, and vest, 46 ; and 

 coat, waistcoat, shirt, and vest, 83. 



t ' Some Thoughts concerning Education.' 



