Page:Popular Science Monthly Volume 26.djvu/441

Rh, setting forth the mischievous effects of excessive strain upon the nervous system of scholars, and asking that an end be put to an abuse which "threatens, little by little to reduce the cultivated classes of society to a state of moral weakness that shall render them incapable of great and manly resolution."

Effects of Tobacco on Youth.—Dr. G. Decaisne has made special observations of the effects of tobacco in thirty-eight youths, from nine to fifteen years old, who were addicted to smoking. With twenty-two of the boys there was a distinct disturbance of the circulation, with palpitation of the heart, deficiencies of digestion, sluggishness of the intellect, and a craving for alcoholic stimulants; in thirteen instances the pulse was intermittent. Analysis of the blood showed, in eight cases, a notable falling off in the normal number of red corpuscles. Twelve boys suffered frequently from bleeding of the nose. Ten complained of agitated sleep and constant nightmare. Four boys had ulcerated mouths, and one of them contracted consumption, the effect. Dr. Decaisne believed, of the great deterioration of the blood, produced by the prolonged and excessive use of tobacco. The younger children showed the more marked symptoms, and the better-fed children were those that suffered least. Eleven of the boys had smoked for six months; eight, for one year; and sixteen, for more than two years. Out of eleven boys who were induced to cease smoking, six were completely restored to normal health after six months, while the others continued to suffer slightly for a year.

Danger from Overhead Wires.—Professor Sylvanus P. Thompson mentions as one of the most solid objections to overhead wires, that they are a permanent and absolute source of danger, because every wire of whatever kind deteriorates more or less slowly under atmospheric influences, especially in the smoky, sulphur-laden air of cities. Those best qualified from long experience to speak on the subject agree that the life of every wire is limited, and no one can tell how or when it will snap. The fact has been established by Professor Hughes that every vibration imparted to a wire brings it a stage nearer to a state of internal crystallization, when, its fibrous structure having become completely degenerated, it snaps short. He has measured the number of vibrations which determine the length of life of wires of different kinds, and finds it to be varying according to the material, but limited in every case. "Given at first a wire of ideal perfection, when it has swayed to and fro its allotted number of hundreds of thousands of times in the breezes, it must snap. But no such wire is attainable; all are more or less faulty, and can not be relied on, even with the most diligent inspection, when once set up in the smoky air." Numerous accidents, according to Mr. Preece, have arisen from the falling of wires, and a case is on record where an omnibus-driver was decapitated from such a cause.

Atmospheric Action on Sandstone.—M. E. Wadsworth, of Cambridge, records certain observations on St. Peter's and Potsdam sandstones, made several years ago near Mazomanie, Wisconsin. The St. Peter's sandstone is composed almost wholly of a pure quartz sand, and in the outliers of it, found on the hill-tops south of the town, the parts covered by the soil were more or less friable, and the grains distinct; while the exposed portions of the same blocks and slabs were greatly indurated, the grains being almost obliterated, and the rock possessed the conchoidal fracture and other characteristics of a quartzite. In the autumn of 1872 a block of clear white Potsdam sandstone was found, the protected side of which was friable, while the other sides, especially the one most exposed to the prevailing storms, was nearly a quartzite. This block was only about two feet square, and, as a test of the correctness of the above conclusion, the indurated surface was broken off, and a comparatively friable surface exposed. This locality was visited the following spring, when the fresh surface was found much indurated, and approached toward a quartzite.

Phosphoric Glass and its Applications.—At a recent meeting of the French Academy of Sciences, a number of articles were presented for inspection that were made of a glass composed simply of phosphate of lime. The new application is the invention.