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THE POPULAR SCIENCE MONTHLY. 



Scotch lakes, in winter as well as in sum- 

 mer, Professor Nichols is led to the conclu- 

 sion that " the watei of lakes and ponds is, 

 as a rule, before freezing, cooled to a temper- 

 ature 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 re- 

 cording 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 vear 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 vears asro, 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 re- 

 ceived from thirty-nine schools, in relation 

 to the points of the character of the situa- 

 tion and buildings, and the climatic con- 

 ditions ; 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 par- 

 ticular 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 be- 

 tween 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 defect- 

 ive 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 oc- 

 curred during the year, one never having oc- 

 casion 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 fif- 

 teen 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 ty- 

 phoid fever in one. Many of the schools 

 have provision of some kind for the isola- 

 tion 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 ar- 

 rangements 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, gener- 

 ally 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 mar- 

 row 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 



