Notices respecting New Boohs, 391 



every branch of what is now a science in itself. How much the 

 science covers and the manner of its development could not be 

 better told than in the eight pages which introduce this work, 

 where, it is gratifying to note, generous and unreserved acknow- 

 ledgment is made of the part played by workers in this country 

 md the services rendered by Rutherford's treatise. 



The book itself appears to have been in preparation for a 

 considerable time, and both in the scheme of presentation and the 

 order of the subject-matter reflects the growth of ideas as it took 

 place in France, where the view that radioactivity was due to 

 atomic disintegration, now everywhere adopted, was for a 

 considerable time not accepted. Indeed in this respect it is largely 

 autobiographical, as is perhaps only natural, the discovery and 

 investigation of the powerfully radioactive elements, and their 

 "induced" activity and emanations, occupying the first volume 

 and preceding the detailed study of the radiations and of the suc- 

 cessive members of the various disintegration series, which form 

 the chief contents of the second. In treatment and scope the book 

 is thoroughly comprehensive, and practically all the important 

 physical and chemical work which has been published is referred 

 to. It will be welcomed in this country particularly as containing 

 an authoritative account of the work of M. and Mme. Curie, much 

 of which, owing to the prevailing custom in France, has hitherto 

 only been very briefly published. 



Les Compteurs electriques a Courants conthius et a C our ants alterna- 



tifs. By L. Baiibillicxn" and G. Feeuoux. Paris : Gauthier- 



Villars, 1910. — Notions fondamentahs sur la Telegraphie. By 



A. Turpain. Telephonic By A. Turpain. Paris : Gauthier- 



Yillars, 1910. 



These three small treatises deal each with a particular branch of 



technical electricity. The first is a specially clear and elementary 



account of electric meters adapted to measure either continuous 



or alternating currents. A very large number of different patterns 



are described and the theory of them sufficiently outlined. The 



discussion of meters depending upon rotary fields is especially 



good. The book is profusely illustrated with figures and diagrams. 



In the second book, Professor Turpain outlines the historical 



development of electrical telegraphy, and the volume will be found 



useful to all those interested in this development. No theory, 



in the ordinary sense, is given ; attention is concentrated on 



the mechanical devices, such as relays &c, rather than on the 



theoretical side. The details of the instruments used are very 



clearly drawn. 



The third volume, also by Professor Turpain, is of a similar 

 scope. The main portion is taken up with a description of 

 central stations. The author has a vigorous style, and he grows 

 sarcastic at theoretic attempts to explain the action of a telephone. 

 One chapter is headed : " L'explication precise du phenomena 

 telephonique parait impossible.'" 



