Page:Handbook of Meteorology.djvu/21

Rh Water vapor and the unmeasured dust content of the atmosphere are meteorological factors of the highest degree of importance. All the fresh waters of the earth are derived from the sea by a process that is clearly one of distillation; and life as it is organized on the earth depends upon this process. Even a slight change in nature’s method of distillation would be followed by profound changes in the distribution of life.

 Air and Mortality.—The difference between the sun-bathed air of out-of-doors and the air of dwellings has exerted a marked effect upon modern civilization. Various diseases of the densely peopled regions of Europe and America are practically unknown among peoples who live habitually out of doors. Tuberculosis is essentially a disease of modern civilization. Even in Europe and America, where the disease thrives, the mortality is twice as great among house dwellers as among those having out-of-door employment.

The mechanical ventilation of buildings has helped matters but very slightly. Air drawn through ventilating shafts has not the same therapeutic qualities as sunlit air coming through open windows into living rooms. An explanation of the difference is yet to be found. If meteorology is the science of the air, it should discover the difference between wholesome and unwholesome air.