Page:Popular Science Monthly Volume 20.djvu/490

474 sometimes exaggerated—there was a time when many believed that it would remove all sickness, and it would not be surprising if the reaction against this exaggeration should lead to an undue depreciation—but it is an established fact that every city that has completed a well flushed system of sewerage in connection with house-drainage has gained in health, and that its death-rate, especially from diseases connected with the soil, has diminished. I mention the reports, on the frequency of typhus before and after sewerage, of John Simon for the English cities, of Varrentrapp for Frankfort-on-the-Main, and of Lievin for Dantzic. We hear, indeed, that the general prevalence of typhus has ceased, and that its disappearance in these cities is wrongly placed to the credit of costly sanitary works; but the coincidence must be full of significance to every unprejudiced person that the disappearance of typhus in different cities has not taken place simultaneously and in the same degree, but has generally begun with the introduction of water-works and sewers. In Hamburg, for instance, improvement began to be evident in 1848, and in Dantzic in 1872. If now we conclude that the genius epidemicus has undergone a change, this genius must have manifested a wicked partiality for Hamburg and a devilish maliciousness toward Dantzic, to have kept the latter city so long in his claws. Soyka recently communicated to the meeting of the German Sanitary Union a statistical report respecting the typhus in Munich, in which the influence of sewerage was set forth in the plainest manner, perhaps more plainly than it has been done in any other case. It is known by long experience in this city that abdominal typhus, when it is epidemic, prefers certain quarters, including sewered and unsewered parts alike, and that it spares certain quarters, including sewered and unsewered parts alike; showing that the disease is generally connected with the local situation, not with the existence or nonexistence of sewers. Now, Soyka has found that between 1866 and 1880 typhus diminished in the unsewered and the old and badly sewered parts of the city, in round numbers, only ten per cent, in the favorably situated and well-sewered parts about twenty per cent, in the unfavorably situated but well-sewered parts about forty per cent'. That the wonderful result in the last case was accomplished by sewerage becomes obvious when it is considered that in it an otherwise fertile typhus-field, in which more seed was to be destroyed, had to be dealt with. Such facts make it very hard for the opponents of sewerage to continue to deny its hygienic advantages.

A well-regulated system of sewerage with adequate flushing not only promotes the removal of much filth, but also effects a great dilution of all soluble and floating dirt, and contributes toward rendering it harmless and effecting its complete destruction. The opponents of sewerage insist that it is impossible to construct a perfectly tight system of sewers. This is not essential; it is enough to reduce the quantity of impurities penetrating into the soil, so far as they are of