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THE POPULAR SCIENCE MONTHLY.

Scotch lakes, in winter as well as in summer, Professor Nichols is led to the conclusion that "the water of lakes and ponds is, as a rule, before freezing, cooled to a temperature much lower than 4° Cent. (39° Fahr.), not simply at the surface, as generally stated, but to a considerable depth. The commonly received idea and the current statements of the text-books of chemistry and physics, are, therefore, misleading." The temperature of the water at the bottom of deep lakes is, moreover, not constant at the point of greatest density, as is frequently stated, but often lies appreciably above that point. Professor Nichols is not satisfied that we know sufficiently well the depth to which the diurnal variations of temperature extend under different circumstances. The curves of temperature in Mystic Pond show that there were several times when a few successive days of warm or cold weather produced an effect on the water, even at a depth of seventy-five feet. The paper recording these observations is supplemented by a list of other publications and papers bearing on the subject.

 

Sanitary Reports of British Schools.—The "Lancet" about a year ago addressed a series of questions to the managers of English schools respecting their sanitary provisions and the health of their pupils. The answers which it has received indicate that the subject is given considerably more attention than it was a few years ago, and that many of the managers sympathize with the editor in the object of his inquiries—that of ascertaining the conditions of the best scholar-health. The first report made by the journal summarizes the replies received from thirty-nine schools, in relation to the points of the character of the situation and buildings, and the climatic conditions; the amount of air-space per pupil in the sleeping and school-rooms; general state of health, cases of illness; sanitary arrangements as regards drainage, closets, lavatories, bathing, towels, etc.; provisions for the isolation of contagious cases; and provisions for medical inspection. No particular relation seems to be shown between the presumed healthful or unhealthful character of the site, and the presence or absence of disease. The sleeping-rooms afford from 273 to 1,300 cubic feet of air per individual; if the schools were full, the probable average allotment would be between 300 and 400 feet. The provision of air in the school-rooms is "fairly ample." The drainage is pronounced good in nearly every school, and no cases of illness are mentioned which could be traced to defective drainage. Lavatory arrangements are well attended to, with provisions for hot, cold, and swimming baths, and separate towels, brushes, etc., for each boy. Eight schools report that no cases of illness occurred during the year, one never having occasion to send for the doctor. The diseases mentioned include ophthalmia in two schools, pneumonia in two, "congestion of the lungs" in two, peritonitis in one, rheumatic fever and erythema nodosum in one, and sore-throat in one. Measles occurred in fifteen schools (fifteen cases in one), scarlet fever in twelve (fourteen cases with one death in one school), varicella in two, mumps in three (thirty cases in one school), Rotheln in three, whooping-cough in two, and typhoid fever in one. Many of the schools have provision of some kind for the isolation of pupils sick with contagious disease. Only five schools have arrangements for systematic medical inspection. The value of these returns is modified by the fact that the schools having the best sanitary arrangements and showing the best condition would naturally be the ones most ready to report.

 

Recent Existence of the Mastodon.—Professor Collett's "Geological Report of Indiana for 1880" mentions some new facts that seem to indicate that the mastodon existed in our country at a more recent date than is commonly supposed. In nearly all the specimens that have been found, generally in places where the animal has been mired, the skeletons are in a greater or less state of decay. In a skeleton discovered a few years ago, in Fountain County, the marrow of the larger bones was used by the workmen to grease their boots, and the place of the kidney-fat was occupied by lumps of adipocere. During the summer of 1880 a mastodon was found in Iroquois County, Illinois, that gave every evidence of having lived among the same life and