Page:Popular Science Monthly Volume 14.djvu/61

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tality, either in plants or animals. These putrefactive processes either give rise to the formation of poisonous bodies, or they act simply as ferments, generating similar processes of decomposition in the substances composing the animal organism."

The "controlling vitality" of plants and man have widely differing requirements: what is food to one is to the other poison, and sewage polluted water is just what the Brighton gardener uses.

Dr. Corfield says, in a lecture before the Royal School of Military Engineering at Chatham, that ". . . mere passage over the soil will not purify sewage satisfactorily. The effluent water which goes off the land is, to all intents and purposes, sewage." And Mr. Denton, a distinguished engineer and scientist, says, in a lecture before the same school, that ". . . water collected from the surface of cultivated lands, and from the under-drains of cultivated lands, is always more or less polluted with the organic matter of manure, even after subsidence in lakes or reservoirs." Shallow-well water is declared by the Rivers Pollution Commissioners to be the most dangerous of all waters, "whenever the wells are situated, as is usually the case, near privies, drains, and cesspools;" and it is this shallow-well water that Denton refers to when he goes on to say the commissioners declare that "such polluted surface or drainage water (referred to above) is not of good quality for domestic purposes, but it may be used with less risk to health than polluted shallow-well water, if human excrementitious matters do not form part of the manure applied to the land." Mark this, on the highest authority, that shallow-well water, the most dangerous stored well-water known, is safer to drink than the effluent water from such slopes as this article describes. When it is added that the Royal Commissioners, having examined the waters of some four hundred and twelve shallow wells in different geological formations, pronounce them all, with few exceptions, "entirely unfit for human consumption," the force of the objections raised against the water from the foul slopes may be appreciated.

It may be suggested that filtering be resorted to, or the sewage "disinfected," as some are pleased to call certain processes. But the English commissioners say that "as applied to sewage, disinfectants do not disinfect, and filter-beds do not filter. Both attempts have been costly failures." And again they say, "No process has yet been devised of cleansing surface-water once contaminated with sewage, so as to make it safe for drinking." To this the late Mr. Kirkwood, the distinguished American engineer, adds, ". . .If this view of the case may seem to be over-cautious, it is to be remembered that the poison, however trifling, is taken daily, and that, although when in robust health the individual will not suffer from it, it may be sufficient to make itself felt when he is prostrated by sickness, and his powers of resistance to such influences are then proportionally impaired."

It has been supposed that if the sewage be applied to these slopes