How to live in tropical Africa : a guide to tropical hygiene. The Malaria problem : the cause, prevention, and cure of malarial fever / by J. Murray.

  • Murray, J.
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: How to live in tropical Africa : a guide to tropical hygiene. The Malaria problem : the cause, prevention, and cure of malarial fever / by J. Murray. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

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    sun is withdrawn : also, because the sun cannot warm the air devoid of moisture and other floating matter, so under fierce sunlight the mountain snows may be per- petual.”* The air is said to be saturated when it contains the greatest amount possible of watery vapour at a given temperature. If from any cause there is a sudden lower- ing of temperature, cloud, fog, mist, rain, snow, or hail will result. As all these keep off solar heat, a knowledge of the moisture and cloudiness of a place is necessary to determine its temperature and suitableness for residence. “Water itself absorbs 80 to 90 per cent, of heat in very thin layers of o‘02 to C27 inches, and vapour of water would, could it be examined, do likewise. Also, the absorption is in proportion to quantity or thickness of moist air. Thus, under pressure of 5 inches, 16 per cent, of heat was absorbed by the moist air in experiment tube, but under a pressure of 30 inches, 98 per cent.”f Local conditions largely determine rainfall and humid- ity of a place. Mountains, especially when wooded, collect watery vapour on the side exposed to the moist winds. When these are strong, they are forced mechanically to ascend the inclined surface of the range into cooler regions, where they are condensed into clouds, rain, snow, or hail. This effect is most marked in mountains over 1,500 feet high, but it commences with those of 500 feet elevation or under. If the range is over 2,000 feet high, the rain mostly falls on the side exposed to the wind. Cold winds meeting warm ones can also condense their vapour. * Floating Matter of Air. f Tyndall—Heat a Mode of Motion.
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