It has been observed by medical men, from the time of Hippocrates down to
the present day, that the effects of a heated atmosphere, saturated with
moisture, are very injurious, and exceedingly prolific of disease.
Air at 32 deg. of Fahrenheit, according to Leslie, contains, when saturated
with moisture, 1/160 of its weight of water; at 59 deg., 1/80; at 86 deg., 1/40;
at 113 deg., 1/20; its capacity for moisture being doubled by each increase of
27 deg. of Fahrenheit.
The degree of heat within the stockade sometimes rose to beyond 110 deg.
Fahrenheit, and the degree of humidity was correspondingly as great. That
moisture exerts more influence in the production of disease than any other
meteorological condition, is well observed in every-day life. M. Bossi
found, in his investigations, that the extreme and constant humidity of
the atmosphere affected the barometer of health very markedly, and he
established the following ratio of mortality for the different regions:
The ratio for mountains and elevated regions he observed to be one in
thirty-eight; on the banks of rivers, one in twenty-six; on the level
plains, sown with grain, one in twenty-four, and in parts interspersed
with pools and marshes, one in twenty.