ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 287 



Part III. — Various Atmospheric Conditions and Phenomena. 



TEMPERATURE AND HEALTH. 



The relation of the temperature of the air to health has already been 

 noted in the case of various diseases. Thus malaria, dysentery, liver 

 diseases, cholera, yellow fever, and dengue. belong especially to hot 

 climates. Anaemia and general enfeeblement affect the inhabitants of 

 colder regions when stationed in the tropics. Hot weather in northern 

 Europe increases the prevalence of several diseases, and with drought 

 increases the death rate in towns and damp places. Diarrhea becomes 

 prevalent, and in less degree scarlet fever and diphtheria. Diseases of 

 the intestines increase. Cold, dry, still weather is generally healthy 

 except in towns, and to old people, and to persons whose lungs are 

 delicate. A cold winter in temperate climates increases the death rate, 

 and a mild winter is healthy in northwestern Europe. Influenza, pneu- 

 monia, and bronchitis are more fatal in cold weather. Diseases of the 

 circulatory system, heart disease, and phthisis are at their maximum of 

 fatality. Cold, clear, still, frosty weather is, on the whole, healthy and 

 much less fatal iu towns than cold with fog. 



The most favorable temperature to health in temperate climates is 

 about 55° to 70° on an average; natives of the tropics probably thrive 

 best at a temperature of about 65° to 80°. 



DRY CLIMATES AND HEALTH. 



A perennially dry air is almost universally favorable to human life, 

 and dryness in a sparsely inhabited and well-watered country is whole- 

 some in several ways, especially, perhaps, in its preventive effect on 

 epidemic and lung diseases. In towns, dry weather without showers 

 is much less favorable, in fact it is distinctly unfavorable. Very damp 

 and rainy countries with moderate temperature are often healthy; for 

 instance, western Ireland, western Scotland, Cornwall, and the lake 

 district of England. The deaths from consumption, etc., are much 

 fewer in these districts than in the drier districts which are more 

 thickly inhabited, though not less, perhaps^ than in equally sparsely 

 inhabited drier country districts. That they are so numerous as they 

 are depends probably very much on the tendency to aggregation and 

 bad ventilation in the dwellings in bad weather. Tropical or warm 

 couutries, and warm seasons, in many localities, are unwholesome when 

 there has been much rainfall, and this is succeeded by hot weather. 

 Much moisture in a calm air helps greatly to spread various epidemic 

 diseases and malaria. Dry air is favorable to the healing of wounds, 

 and probably to the oxidation or death by desiccation of noxious living 

 matter in the air. 



The exemption of many tribes and races living in dry climates from 

 phthisis and other disorders of an infectious nature may be, and 



