CLIMATE 995 



is a sufficient food -supply, but under the condition of 

 starvation cold readily kills. Extremely low temperatures 

 are tolerated provided the air is still, while a moderate 

 degree of cold is intensely felt if a wind is blowing, for a 

 dry wind causes a loss of heat to the body. 



The effect of a reduction in atmospheric pressure, such 

 as is obtained at high altitudes, causes at first a difficulty 

 in breathing, as owing to the expansion of the air insuffi- 

 cient oxygen enters the blood ; but this after a short 

 residence passes away, though we are told* that animals 

 working on the Cordillera of Peru suffer from a disease 

 known as reda, which shows itself by great difficulty in 

 breathing and muscular tremors. Animals so affected die 

 if not rested. 



At considerable elevations there is generally a more active 

 movement of the atmosphere, and the air ia drier. The air 

 on the Cordillera is so remarkably dry that a dead animal 

 becomes mummified in the course of a few days with, it is 

 said, no evidence of decomposition. 



The temperature at high altitudes is hable to great daily 

 variations, the days may be hot, while the rapid radiation 

 after the sun sets produces considerable cooling and lower- 

 ing of air temperature. 



At moderate altitudes, say up to 4,000 feet, there is no 

 evidence whatever among animals that they experience the 

 slightest difficulty in breathing, and certainly none in work. 

 So adjustable is the organism that neither a reduction nor 

 an increase in atmospheric pressure within moderation 

 produce harmful effects. Animals continue to work in deep 

 mines for years and never come to the surface ; the fact of 

 their working for years shows that they must enjoy a large 

 measure of health ; their breathing and circulation may be 

 slower, but there are no other observable conditions the 

 result of the increase in pressure. Sudden reductions in 

 body pressure are very harmful, they are seen in divers 

 and men working in caissons ; sudden reductions in 



* 'Influence of Atmospheric Pressure and Altitude.' The late 

 Dr. Fleming, F.E.C.V.S., Veterinarian, 1868. 



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