September 8, 1893.] 



SCIENCE. 



139 



others, however, have not been so fortunate. Thrown 

 into out of the way places in the exercise of their profes- 

 sion, they have not had the opportunity or time' to follow 

 uj) the subject. 



To such this little book may be recommended as an 

 introduction to the more mathematical treatises of Flem- 

 ing, Blakesley, and Crehore and Bedell. 



It deals with the subject in the most elementary way, 

 so simply that it is practically impossible for any one 

 with the most superficial knowledge of electricity not to 

 arise from its j)erusal without a knowledge of the main 

 characteristics of an alternating current, how it differs from 

 a continuous current, the princiiDles of the working of alter- 

 nating current apparatus, and the ability to read the more 

 mathematical treatises comprehendingiy and understand- 

 ingly. 



The introduction is somewhat of a disappointment, 

 as it contains, with the exception of a pertinent warning 

 against the fallacy of supj)osing that the field produced by 

 a two-phased current is more irregular than that of a three- 

 phased current, practically nothing but a review of the 

 book. One feels that more might have been looked for 

 from one who has been so long in alternating current 

 work and has done so much for its development. 



There are few things that can be criticised in the book it- 

 self. The mathematical proof of the expression for the mean 

 current, given on piage 45 might be altered for the better, 

 as it is not usual to change the variable in an integral 

 without changing the limits between which the integral 

 is taken, nor to integrate an angular expression between 

 time limits. 



The explanation of magnetic leakage on page 95 may 

 also be objected to. Lines of magnetic induction are 

 caused by a magneto-motive force, and magneto-motive 



force is a vector quantity. Consequently, when two 

 magneto-motive forces are superimposed, there is not a 

 formation of lines of magnetic induction corresponding 

 to each of the magneto -motive forces, but one set of lines 

 corresponding to the resultant m. m. f. 



In conclusion it may be said that, to those who are in 

 want of a very elementary book on alterning currents, this 

 treatise will supply what is desired. 



E. A. F. 



The last number of Vol. V. of the American Journal 

 of Psychology, which has just been issued, contains prac- 

 tical suggestions on the equipment of a psychological 

 laboratory by Dr. E. C. Sanford. A study of Pseudo- 

 chromesthesia, mostly among the students of Wellesley 

 College, by Professor Mary W. Calkins, illustrated by 

 many new^ diagrams and tables. A brief system of 

 Ejective Philosophy, in seven pages, by T. P. Bailey. 

 An attempt to explain the Hegelian Philosophy psycho- 

 logically, by A. Fraser. The longest and most popu- 

 lar article is an account of the Neo-Christian Movement 

 in France, by J. H. Leuba, a Frenchman by birth and 

 education and Fellow at Clark University. The artistic 

 sensualists, Huysmans, Beaudelaire, the school of de- 

 cadents, illustrated by Kahn Rene Ghil and Mallarme ; 

 "the literary critics and chronicles, " "the tormented," 

 like G. Duruy, Jounet, Lasserre, Bouchor, Bourget, 

 etc., are characterized with just discrimination and 

 knowledge. The Neo-Christian movement proper, 

 represented by Lavisse, De Vogue and Desjardins, 

 concludes a sketch which constitutes by far the best 

 presentation of these remarkable literary movements 

 that have yet appeared in English. The usual reviews 

 follow. 



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