Page:Popular Science Monthly Volume 31.djvu/736

718 over pain, there is in brutes a still greater surplus; if in humanity there be anything like an equality between pleasure and pain, there is in brutes a large preponderance of pleasure; if in humanity pain predominate, then in brutes the proportion should be reversed."

Air in Dwellings and School-Rooms.—In the experiments of Professor Carnelly on the air of dwellings and schools, and its relations to disease, a distinct increase of impurities was detected in the air of the close parts, as compared with the open spaces, of such towns as Perth and Dundee. As between different classes of dwelling-houses, one-, two-, and four-roomed dwellings, the average length of life in the one-roomed house was only twenty years, while in the better-class houses it was forty years. Hence, persons born and living in a one-roomed house have a chance of living only half as long as those born and living in a four-roomed house. This depends naturally to a considerable extent on other causes than impure air-supply. The best results in the relation of atmospheric purity to cubic space were noticed when the allowance was one thousand cubic feet for each person. The result, owing to stagnation, was not so good in larger rooms. Of sixty-eight school rooms in Dundee, twenty-six were mechanically ventilated, and the others were ventilated by means of windows. The advantage was found to be decidedly on the side of mechanical ventilation, which not only materially improves the quality of the air, but also causes less reduction in its temperature. The air was less pure in boys' schools than in girls' schools. Cleanliness of person had a comparatively small influence on the number of micro-organisms, but cleanliness of dwelling-rooms and schools had a most important effect. Hence, the air of new school-rooms is distinctly better than that of older buildings. The author suggests that the evil said to be due to over-pressure in schools is, in many cases, due to imperfect ventilation.

How Lampreys build their Nests.—In a paper on "Lampreys of Cayuga Lake," read at the American Association, Messrs. S. H Gage and S. E. Meek held that the study of the specific characters of these animals had convinced them of the specific identity of the sea and Cayuga Lake lamprey, and that the alleged specific differences are but seasonal and individual variations. In the spring, May and June, the lampreys ascend the largest of the streams flowing into the lake for the purpose of spawning. They build nests of stones in the bottom of the stream, usually just above declivities where the water breaks in ripples. In forming the nests the stones are removed, forming a circular or oval place, the diameter of which is a little more than the length of the lamprey. In removing the stone the lamprey fastens its suctorial mouth to the stones, wriggling strongly until the stone is loose. It then raises it free and floats down with the current to the lower edge of the nest, where the stone is dropped. In this way all of the stones are removed for a depth of from ten to twenty centimetres. As nearly all of the stones are piled up at the lower edge of the nest, that is the highest. The current carries down into the nest fine gravel, partly filling it. When the eggs are laid, the sand is stirred up, and the eggs being heavier than water sink with the sand and are covered by it. Lampreys if placed in an aquarium with other fishes will attach themselves to them and produce wounds.

Value of M. Pasteur's Hydrophobia Inoculations.—A committee appointed by the British Local Government Board to inquire into M. Pasteur's method of treatment of hydrophobia made a report in June, 1887. The committee consisted of Messrs. James Paget, T. Lauder Brunton, George Fleming, Joseph Lister, Richard Quain, Sir Henry Roscoe, and J. Burdon-Sanderson—men whose judgments in the premises can be relied upon if those of any men can. The committee visited Paris; made special examinations of ninety of M. Pasteur's earliest cases who were within easy reach of the capital; and through its secretary, Mr. Victor Horsley, made careful experiments on the effects of M. Pasteur's inoculations on the lower animals. The conclusion of the committee is expressed, after relating its observations, in the words: "From the evidence of all these facts, we think it certain that the inoculations practiced by M. Pasteur on persons bitten by rabid animals have prevented the occurrence of hydrophobia in