possible to work or perform a duty or task assigned. The first 

 lesson is to learn to conserve body heat which can be lost ex- 

 tremely fast to the cold surrounding air. There are two ways 

 which will help to attain comfort and save body energy. One is 

 proper wearing and use of the special clothing provided ; the other 

 is acclimatization or becoming accustomed to a colder environment 

 than normally desirable. The success of the first depends on 

 adaptation; the success of the second depends on how well body 

 machinery adjusts itself to the cold. 



Actually, the body is very much like a gas engine. The food 

 eaten is the gas. When this food energy is burned by the different 

 tissues in the body, such as the muscles or the brain, about 20 

 percent of the energy is used in doing work and about 80 percent 

 is liberated as heat — just about the same ratio as that of an engine. 

 The lungs are the carburetor, intake, and exhaust through which 

 oxygen is drawn in, mixed with the blood, and the waste gas 

 (carbon dioxide) eliminated. The heart and blood are the fuel 

 pump and line ; they force the absorbed food and oxygen through 



Figure 5-1 . — Avoid perspiration (loosen clothing or remove coat). 



158 



