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Page:Popular Science Monthly Volume 56.djvu/411

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397
FRAGMENTS OF SCIENCE.

for drinking or cooking—provided the flow of the stream is always copious enough to dilute and disperse the sewage so widely as to prevent putrefaction and substitute oxidation. For purification by bacterial action no single method is found adapted to all conditions. The method by filtration and aeration is declared practicable only in localities where a sufficient area of porous land is available, upon which the crude sewage can be spread in sufficient quantity, into which it can filter with the proper velocity, and from which it can emerge as a thoroughly purified water. Where these conditions are absent, other methods must be adopted, of which the experiments in artificial filtration by tanks, as practiced at Exeter and Sutton, England, are described. These experiments promise to improve the present method, but perhaps not as greatly as is anticipated by the promoters. The author regards a prior separation of the suspended or dissolved organic matter as essential to permanent success when the amount of land is limited.

By using the tuberculin test the faculty of the Ohio Agricultural Experiment Station have learned that in cattle the tubercle bacillus usually first obtains its foothold in some of the minor glands, that it may exist there for months and years before any other organs are affected, and that it is only in advanced cases that the lungs become diseased. While the growth of the organism is limited to these minor glands the health of the animal usually shows no sign of impairment. During this period there is no evidence that any unwholesome effect is being produced upon the flesh, and so long as the infection is localized in this way in one or two organs the Government inspectors pass the meat as sound. Tuberculosis, therefore, is a very different complaint from such diseases as pleuropneumonia or Texas fever, in which the whole system is saturated from the first instant with the febrile symptoms.


NOTES.

Mr. James Weir tells of a spider which stretched its web in the division between two parts of a sawmill, where the lower fastenings of the structure were frequently broken by the repeated passing of lumber through. Discovering the situation, the insect gave up the use of guy threads, and, finding a nail, wove it into the lower edge of its web, so that it should operate as a sinker to keep the web stretched.

N. G. Johnson, of the Maryland Agricultural Experiment Station, telling the Society for the Promotion of Agricultural Science the story of his fight with the pea louse, represented that the pea raisers in his State had lost this year more than three million dollars by the ravages of this insect. A parasite bad been discovered which practically annihilated the pest, but the discovery was not made in time to save the crops in some parts of the State from destruction.

The American Society for the Promotion of Agricultural Science, after hearing the account of the work of the Gypsy Moth Commission of Massachusetts, which has spent more than a million and a half of dollars in trying to exterminate the mischievous insect, approved the action of the Massachusetts Legislature in maintaining the commission, and requested that the work be kept up for a short time longer. This was because it was represented that the moth was now confined to a limited area, and could be easily exterminated by the expenditure of a small amount more of money.

The history of science has sustained a great loss by the burning of most of the relics which had been collected for the Volta Centenary Exhibition at Como, Italy. Only a few things were saved, comprising a sword presented by Napoleon Bonaparte to Volta, a cast of the skull of the great electrician, his watch, and a few personal relics. On the other hand, his books and manuscripts, his collection of batteries, the only authentic portrait of him, and his will, were destroyed. Nevertheless, the celebration was not stopped. The fire was attributed to the fusing of some electric wires.

An example of patient industry is the sorting of hogs' bristles as it is carried on at Tientsin, China. Each one of the hairs of the six hundred thousand kilogrammes exported from that place in 1897 had to be picked out, measured, and placed in the bundle of hairs of corresponding length; and the different lengths by which the hairs are sorted are very numerous.

It is stated by M. Léon Vaillant that the late M. A. d'Abbadie had and used an effective remedy against the