Page:Popular Science Monthly Volume 14.djvu/56

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clusions. Dr. Folsom, in the "Report of the State Board of Health of Massachusetts for 1876," also attacks this branch of the question, remarking that "excessive dilution simply diminishes the chances of danger from any particular tumblerful." He here states a case of transmission of disease in dilute sewage, to which special attention is invited, as showing quite conclusively the fatal result ensuing from reposing too great faith in the extermination of disease-germs by oxidation, and of reducing the chances of transmitted disease by diffusion of disease-germs through a large body of running water. Dr. Folsom says: "The most striking case illustrating this law is one reported by Dr. E. D. Mapother, of Dublin. Forty cases of typhoid fever occurred in a hospital which received its supply from a river. The cause was traced to some barracks twenty-five miles higher up, from which typhoidal dejections had been emptied through drains into the river."

It would be easy to multiply authorities on this point. Suffice it to say that this pernicious theory is happily exploded, and that the Second English Rivers Pollution Commission publish conclusions, based on the examination of some two thousand samples of water claimed to be drinkable, condemning river-water because it is liable to contamination from drainage of cultivated land, towns, and manufactories. They state that "the admixture of even a small quantity of these infected discharges (of persons suffering from cholera or typhoid fever) with a large volume of drinking-water, is sufficient for the propagation of those diseases among persons using such water." The case related by Dr. Folsom, previously quoted, as well as numberless others of a similar sort, proves the accuracy of this conclusion.

The English commissioners then classify potable waters as follows, and, when we consider the high authority for this scale of wholesomeness, it would seem that it should carry great weight with it. Though often published before, it cannot be too frequently repeated:

1. Spring-water.
2. Deep-well water.
3. Upland surface-water.
(Very palatable.)
4. Stored rain-water.
5. Surface-water from cultivated land.
(Moderately palatable.)
6. River-water to which sewage gets access.
7. Shallow-well water.

While wholesale river-pollution from any source is utterly inadmissible on any sanitary grounds, so infinitesimal pollution by dilute sewage, indirectly discharged into the water-course, is equally dangerous, and attended with sure though more remote fatal results, "especially if human excreta he present in any form whatever." The whole subject is intimately connected, but it is to this latter point more particularly that this paper leads, as touching the pollution of entire