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THE POPULAR SCIENCE MONTHLY. 



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 re- 

 versed." 



Air in Dwellings and School-Rooms. 



In the experiments of Professor Carnelly on 

 the air of dwellings and schools, and its re- 

 lations to disease, a distinct increase of im- 

 purities was detected in the air of the close 

 parts, as compared with the open spaces, of 

 such towns as Perth and Dundee. As be- 

 tween 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 mechani- 

 cally ventilated, and the others were venti- 

 lated by means of windows. The advantage 

 was found to be decidedly on the side of 

 mechanical ventilation, which not only ma- 

 terially improves the quality of the air, but 

 also causes less reduction in its tempera- 

 ture. The air was less pure in boys' schools 

 than in girls' schools. Cleanliness of per- 

 son had a comparatively small influence on 

 the number of micro-organisms, but clean- 

 liness 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 sug- 

 gests that the evil said to be due to over- 

 pressure in schools is, in many cases, due to 

 imperfect ventilation. 



IIow 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 as- 

 cend 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 lam- 

 prey. In removing the stone the lamprey fas- 

 tens its suctorial mouth to the stones, wrig- 

 gling 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, part- 

 ly filling it. When the eggs are laid, the 

 sand is stirred up, and the eggs being heav- 

 ier than water sink with the sand and are 

 covered by it. Lampreys if placed in an 

 aquarium with other fishes will attach them- 

 selves to them and produce wounds. 



Value of M. Pasteur's Hydrophobia In- 

 ocnlations. 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 re- 

 lied upon if those of any men can. The 

 committee visited Paris ; made special ex- 

 aminations of ninety of M. Pasteur's earliest 

 cases who were within easy reach of the 

 capital ; and through its secretary, Mr. Vic- 

 tor Horsley, made careful experiments on 

 the effects of M. Pasteur's inoculations on 

 tlu' lower animals. The conclusion of the 

 committee is expressed, after relating its 

 observations, in the words : " From the evi- 

 dence of all these -facts, we think it certain 

 that the inoculations practiced by M. Pas- 

 teur on persons bitten by rabid animals have 

 prevented the occurrence of hydrophobia in 



