the body under different pressures. The surface of the body is 

 the radiator and, like any other radiator, the bigger the surface 

 in proportion to the thickness, the faster the loss of heat. So the 

 arms and legs (especially the hands, feet, fingers, and toes) and 

 other extremities such as the ears, nose, and chin are remark- 

 ably efficient radiators. 



The thermostatic control of the body heat is more complicated 

 than in an engine. This is roughly how it works: when exercising 

 or working it is necessary for the body to burn more "gas" (food 

 energy). More air is needed and the lungs simulate a super- 

 charger; breathing is faster and deeper. More heat is generated 

 and the "radiator" is taxed heavily. It is not possible to suddenly 

 increase the radiating surface, but water can be poured on the 

 outside of an overheated radiator, similar to the early practice 

 of pouring water on the radiator of an Old Model T after climbing 

 a hill. The body does this by means of perspiration. But pers- 

 piration in the arctic cold is liable to freeze — either on the skin or 

 in the underclothes — and then the body may also freeze. 



One of the first principles to learn is to* avoid perspiration. 

 Loosen the clothing or take some off, layer by layer, while work 

 is in progress, replacing them layer by layer as body activity is 

 reduced. Remember that uncontrolled perspiration may prove 

 disastrous because it leads to freezing in low temperatures. 



Remember, too, that the cold, outside air rapidly sucks heat 

 from the body. Heat pours out like a stream running down hill. 

 The thermostat in this case controls the amount of heat reaching 

 the radiator by reducing the supply and slowing the rate of flow. 

 That is, the small blood vessels near the skin shut down and the 

 blood thickens so that it does not flow as fast. In this way, the 

 skin temperature is lowered and the body may feel cold. The cold 

 skin in itself is a poor conductor and less heat is lost from it than 

 from the warm skin. 



SEASONAL CLOTHING FOR THE ARCTIC 



Away from the coast, summer temperatures in ice-free regions 

 of the North are sufficiently high to make the wearing of winter 

 clothing or even woolen uniforms decidedly uncomfortable. How- 

 ever, even with high temperatures complete body covering is 

 necessary for protection against the hordes of mosquitoes and 

 biting flies. 



In the interior, if a special summer outfit is lacking, wear wind- 



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