ADDITIONAL TOPICS IN HUMAN BIOLOGY 143 



207. Clothing. The warmth of certain kinds of cloth depends 

 upon the fact that they keep the heat of the body from escaping ; 

 in other words, they are poor conductors of heat. Good conductors, 

 on the other hand, allow the heat to pass off rapidly. This differ- 

 ence in fabrics is largely due to the way they are woven. Wool, for 

 instance, is usually made into cloth that is loose in texture, and thus 

 it can hold a considerable amount of air in its meshes. Now, dry air 

 is a poor conductor of heat. Woolen clothing is, therefore, generally 

 used for winter wear. Cotton and linen are tightly woven, and heat 

 radiation through these materials is rapid. When this takes place, 

 the blood is likely to be driven away from the surface of the body, 

 thus causing a congestion of blood in the internal organs, which is a 

 favorable condition for such diseases as colds, pneumonia, or con- 

 sumption. The same result often follows the wearing of wet cloth- 

 ing, since wet clothing is a good conductor of heat. 



208. Effect of alcohol on body temperature. " The action of 

 alcohol in loivering the temperature, even in moderate doses, is most 

 important. By dilating the cutaneous vessels, it thus permits of the 

 radiating of much heat from the blood. When the action is pushed 

 too far, and especially when this is combined with the action of great 

 cold, its use is to be condemned." l 



" A party of engineers were surveying in the Sierra Nevadas. 

 They camped at a great height above the sea level, where the air was 

 very cold, and they were chilled and uncomfortable. Some of 

 them drank a little whisky, and felt less uncomfortable ; some of 

 them drank a lot of whisky, and went to bed feeling very jolly and 

 comfortable indeed. But in the morning the men who had not taken 

 any whisky got up in a good condition ; those who had taken a little 

 whisky got up feeling very miserable ; the men who had taken a lot 

 of whisky did not get up at all : they were simply frozen to death. 

 They had warmed the surface of their bodies at the expense of their 

 internal organs." 2 



1 Landois and Stirling, "Textbook of Human Physiology." 



2 T. Lauder Brunton, London, "Lectures on the Action of Medi- 

 cine." 



