202 RESPIRATION 



47. The temperature of the human body is about 100 Fah- 

 renheit, and remains about the same through winter and sum- 

 mer in the tropics as well as in the frozen regions of the 

 north. It may change temporarily within the range of about 

 twelve degrees ; but any considerable, or long-continued eleva- 

 tion or diminution of the bodily heat is certain to result dis- 

 astrously. 



48. Man is able to adapt himself to all extremes of climate ; 

 and, in fact, by means of clothing, shelter, and food, is able to 

 create for himself an artificial climate wherever he chooses to 

 reside. The power to resist cold consists chiefly in prevent- 

 ing the heat which is generated by the vital processes of 

 the body from being lost by radiation. Warm clothing, such 

 as we wear in winter, has, in reality, the same temperature as 

 that which is worn in summer ; but, by reason of being thick 

 and porous, it is a bad conductor of heat, and thus prevents the 

 escape of that produced by the body. If woollen fabrics were 

 intrinsically warm, no one would wrap a piece of flannel, or 

 blanket, around a block of ice to prevent its melting in sum- 

 mer. 



49. The faculty of generating heat explains how it is that 

 we are enabled to resist the effects of cold ; but how does the 

 body withstand a temperature higher than its own ? Men have 

 been know to remain several minutes in an atmosphere heated 

 above the boiling-point of water, and yet the temperature of 

 their own bodies was not greatly increased. Those who labor 

 in foundries and glass-works are habitually subjected to very 

 high degrees of temperature, but they do not suffer in health 

 more than those engaged in many other occupations. 



50. The regulation of the temperature of the body is effected 

 by means of perspiration, and by its evaporation. So long as 

 the skin acts freely, and the air freely absorbs the moisture, 

 the heat of the body does not increase, for whenever evapora- 



47. State what is said respecting the temperature of the human body. 



48. Ability of man to adapt himself to different climates ? In what does the power to 

 resist cold consist ? What is said about warm clothing ? 



49. Men in an atmosphere above the boiling-point ? In foundries and glass-works ? 



50. The regulation of the temperature of '.h- ! ;>"!;-. Give tl:e explanation. 



