vi FORM AND FUNCTION 99 



make an effort to resist them. In man the ordinary 

 temperature is 98 and a fraction ; a slight rise above 

 this indicates fever, and a slight decline below it shows 

 a failing of the bodily powers. When in health, the 

 bod\- can be exposed to enormous heat without itself 

 growing appreciably warmer. The sensation of heat 

 comes when great effort is required to keep the normal 

 temperature. In the hottest room in Turkish baths 

 the thermometer sometimes rises to 230° F., and some 

 bathers remain there as long as 20 minutes. But this 

 is far below the record. Doctors Fordyce and Blayden 

 were able to remain some time in a chamber heated to 

 260 F. I have been told that a man who earned his 

 living by feats of this kind, found himself compelled to 

 rush precipitately from a heated oven because some one, 

 who was more scientific than kind, had placed a can of hot 

 water in one corner. Every one knows how oppressive 

 the heat of a hothouse is. The heat of the vapour 

 baths in Russia is said sometimes to rise to 11 6° F., 

 but between this and 260 there is a great gulf. We 

 have in this a hint as to one method of keeping down 

 temperature — viz., by evaporation. Perspiration, or 

 rather the evaporation, to which it gives rise, lowers 

 the temperature of the bod)'. When the air around is 

 so damp that evaporation is slow, even moderate heat 

 is oppressive. When through long exposure to a burn- 

 ing sun, all the available moisture in the body has been 

 exhausted, there results a feverish heat and an uncon- 

 trollable thirst. Under these circumstances, a private 

 soldier will not stop to use his pocket-filter, if he 

 happens to have been supplied with one, but will gulp 

 down the most poisonous filth, though he knows it to 



H 2 



