454: Scientific Intelligence. 



final chapter is upon the effects of hysteresis and Foucault cur- 

 rents; it is to be regretted that this portion of the subject has not 

 been treated at greater length. 



One admirable feature of the book is the adoption of a consis- 

 tent notation throughout, and the collection of the symbols used, 

 with their definitions, in a separate chapter. In this connection 

 a sentence or two maybe quoted Jrom the author's preface, which 

 will probably command the approbation of most readers who 

 object to the abuse of their mother-tongue even in technical periodi- 

 cals. "Over-abbreviation and the introduction of heterogeneous 

 prefixes and suffixes ad libitum the author views as a mania of 

 the da}'-, which proves a source of confusion rather than an aid to 



the reader Tiie introduction of new terms and units has 



been carefully avoided." 



Altogether the work deserves commendation and can scarcely 

 fail to be of great use to students of electricity. 



14. T/te Elements of Physics, Vol.11. Electricity and Magne- 

 tism ; by Edward L. Nichols and William S. Franklin, pp. 

 ix + 261. New York (The Macmillan Co. J. — [t has evidently 

 been the intention of the authors, in this book, to reduce the 

 important laws governing electrical quantities to mathematical 

 expressions, rather than to prepare a comprehensive text-book of 

 electricity. The volume may be not unfairly described as a 

 rather full note-book on the mathematical theory ot electricity 

 and magnetism. It opens wilh an introductory chapter on the 

 treatment of distributed quantities. The ideas and analytical 

 methods presented here are much more difficult than those used 

 elsewhere throughout the book. 



The order of treatment is unusual. The fundamental concept 

 is a magnet which is thus defined (Art 327, a.) : "A bar of steel 

 which has been tieated in a manner to be described later is called 

 a magnet." From this definition are developed the usual 

 expressions for the magnetic quantities, but how the bar of steel 

 was treated is nowhere explicitly stated. The electric current is 

 then defined by the equation F = \lf, where F is the side wise push 

 on a wire of length / in a field of strength/*, and later an electric 

 charge, as the time integral of the current. After a discussion of 

 electrolysis, batteries and resistance, charge is again introduced 

 in the chapter on Electrostatics and defined by Coulomb's law^ 

 as if it were an independent quantity. Succeeding chapters dis- 

 cuss phenomena of discharge, magnetism in iron, induced electro- 

 motive force, thermo-electric currents, practical applications, and 

 mechanical conceptions of the electric and magnetic fields. 



The diagrams are numerous, simple and clear. A little more 

 care should have been exercised in the order of presentation. 

 Terms and instruments are often introduced before they have 

 been defined, or described; e. g. current p. 3)6, battery p. 66, 

 induction coil p. 168. Equations 213 and 238 contain errors for 

 which the proof-reader is to blame. There are numerous^ 

 examples of careless writing. In Art 359 a galvanometer is said 



