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THE POPULAR SCIENCE MONTHLY. 



tage6 ; and his great work on logic took a 

 form which could not have been given it if 

 the author had not been a working natural- 

 ist as well as a logician. In the second vol- 

 ume of his " System of Logic " Mr. Mill says : 

 "Although the scientific arrangements 

 of organic Nature afford as yet the only 

 complete example of the true principles of 

 rational classification, whether as to the for- 

 mation of groups or of series, these prin- 

 ciples are applicable to all cases in which 

 mankind are called upon to bring the vari- 

 ous parts of any extensive subject into 

 mental coordination. They are as much to 

 the point when subjects are to be classed 

 for purposes of art or business, as for those 

 of science. The proper arrangement, for 

 example, of a code of laws, depends on the 

 same scientific conditions as the classifica- 

 tions in natural history; nor could there be 

 a better preparatory discipline for that im- 

 portant function than the study of the prin- 

 ciples of a natural arrangement, not only in 

 the abstract, but in their actual application 

 to the class of phenomena for which they 

 were first elaborated, and which are still 

 the best school for learning their use." 



The Sanitarian. A Monthly Journal, edited 

 by A. N. Bell, M. D. New York : A. S. 

 Barnes & Co. $3.00 per annum. 



The sariitary question is now uppermost 

 in the public mind, and it is gratifying to 

 see that the discussion of it is not going to 

 be kept as a "mystery" in the medical 

 profession. Every human being is con- 

 cerned in this matter ; and, if sanitary 

 science has any suggestions to make, they 

 must be made directly to the people them- 

 selves. This is what the periodical before 

 us aims to do, and this it is doing well. 

 The paper in the August number on the 

 ventilation of the public schools of this city 

 ought to be printed separately and placed 

 in the hands of all the commissioners, 

 trustees, inspectors, superintendents, and 

 other officers connected with the schools 

 not excepting the janitors. The same num- 

 ber contains also the following articles : 

 Cholera stamped out ; Animal Refuse of 

 Large Cities ; Defective Drainage ; Action 

 of Tea on the Human System ; Cholera ; 

 Morbid Effects of Alcohol; the Public 

 Health ; Editor's Table ; Book Notices. 



MISCELLANY. 



Fish-Culture In New Zealand. Last Jan- 

 uary a large quantity of salmon-eggs from 

 English waters was shipped to New Zea- 

 land. They would reach their destination 

 in 112 days, but it was a question whether 

 they would bear so protracted a journey, 

 though carefully packed and surrounded by 

 ice. To determine this question, four boxes 

 of ova, packed after the same manner as 

 those sent to New Zealand, were deposited 

 at the office of a London ice company. 

 After the lapse of 112 days, these boxes 

 were opened, and the temperature was then 

 found to be 38 Fahr. "In one of the 

 boxes," writes Mr. Buckland, "the eggs 

 nearly all contained living fish ; in another 

 they were ' blind,' that is to say, no embryo 

 could be seen in them. In all the boxes 

 there was a certain percentage of eggs which 

 had turned quite white. Some of these 

 white eggs presented a curious appearance 

 namely, a spot exactly the color of a 

 strawberry, which covered a third of the 

 surface of the egg." 



The experiment was on the whole satis- 

 factory, and proves that salmon-eggs may 

 be kept in a healthy condition for 112 days 

 or longer. It is still a question, however, 

 whether the rivers of New Zealand are 

 suited for the cultivation of salmon. Some 

 years ago 1,200 trout-ova were shipped to 

 Victoria, and recently Mr. Buckland re- 

 ceived from that colony a trout weighing 7 

 lbs. If salmon thrive equally well in Aus- 

 tralasian waters, this essay in "practical 

 natural history " will be productive of im- 

 mense benefits to the British colonies in the 

 South Pacific at no distant day. 



New Theory of Boiler Explosions. A 



late number of the American Artisan has a 

 paper by Dr. L. Bradley, on " The Dissocia- 

 tion of Water by Heat as a Cause of Boiler 

 Explosions," in which the author very well 

 shows that such accidents are in many cases 

 produced, not by tension of steam, but by 

 the explosion of oxyhydrogen gas. Dr. 

 Bradley in the first place states very clearly 

 the history of the law of dissociation, or the 

 separation of a compound body into its ele- 

 ments by the force of heat. Under atmos- 

 pheric pressure the two elements of watery 



