April 21, 1916] 



SCIENCE 



575 



on general theory and second on the applica- 

 tion of this theory to particular types of appa- 

 ratus. In the part on general theory we note 

 the author using the crank diagram for vector 

 represention of alternating quantities. This 

 departure from his previous custom (use of 

 the polar diagram) is not due to the conviction 

 that the crank diagram is superior to the polar 

 (in fact the author still thinks the polar dia- 

 gram preferable) but the crank diagram is 

 used to make the text conform with the recom- 

 mendations of the Turin International Elec- 

 trical Congress. This change in Steinmetz's 

 notation will undoubtedly be appreciated by 

 engineering students who, in so far as the 

 writer knows, never were able to see the supe- 

 riority of the polar diagram and who were al- 

 ways somewhat confused in reconciling the 

 almost universally used crank diagram with 

 Steinmetz's pet, the polar diagram. 



The second part of the text on Special Appa- 

 ratus is opened with a brief analysis of the 

 scheme of classification used in presenting the 

 various machines. While the author's classi- 

 fication may upset some of our present notions, 

 the sense of it is at once apparent and it will 

 surely come into favor in the future. The 

 electrical machines discussed fall into one or 

 the other of five broad classes, each class em- 

 bracing all machines operating on a given 

 principle, whether motor or generator. These 

 classes are : Synchronous machines, direct cur- 

 rent commutating machines, synchronous con- 

 verters, alternating current transformers and 

 induction machines. 



Many readers of electrical literature have 

 all of Steinmetz's books; certainly every one 

 should have at least this elementary text on 

 alternating current circuits and machines. 



J. H. M. 



Electrical Engineering. By T. C. Baillie. 



Vol. I. Cambridge, University Press : G. P. 



Putnam's Sons. Pp. 236, 131 illustrations. 



This text, dealing in an elementary fashion 

 with electric circuits, machines and measure- 

 ments, is intended as the introductory volume 

 of a series of electrical texts being published 

 in the Cambridge Technical Series. 



On reading the book nothing new is found, 

 either in subject-matter or method of presenta- 

 tion. There are several other books to be had 

 which cover the same ground in practically 

 the same way. 



The title of the book is apt to mislead one 

 regarding its contents; it might more suit- 

 ably be called an introduction to the subject 

 of electrical engineering. The work covered 

 in the text is ordinarily given in a technical 

 school by the department of physics, as will 

 be evident from a brief review of the contents. 

 The chapters are entitled: Currents of Elec- 

 tricity, Magnetism, Current Measurement. 

 Electromotive Force, Resistance Measurement, 

 The Potentiometer, Batteries and Electric 

 Light. 



The subject-matter is logically presented 

 and is fairly well illustrated by original dia- 

 grams and cuts of commercial apparatus. To 

 the layman desiring a knowledge of some of 

 the underlying principles of electrical engi- 

 neering or to the student attacking the sub- 

 ject for the first time, the text would be very 

 helpful. J. H. M. 



Electrical Instruments in Theory and Prac- 

 tise. By "W. H. F. MuEDOCH and W. A. 

 OsCHWALD. The Macmillan Co. 366 pp., 

 164 illustrations. $2.75 net. 

 The vsriters of this excellent book evidently 

 possess the two requisites for a successful text, 

 mastery of the subject and the ability to ex- 

 press their ideas clearly. One is convinced on 

 reading this book on meters that the authors 

 have carefully considered the theory of the 

 various instruments and have worked suffi- 

 ciently with the meters themselves to grasp 

 the errors which may occur and the ways in 

 which they can best be eliminated. A very 

 useful feature of the book consists of experi- 

 mental data which is liberally given through- 

 out to show how nearly the theory may be ex- 

 pected to agree with practise. 



The first chapter gives a condensed history 

 of the early attempts to measure electrical 

 quantities; it serves well to give the student a 

 proper appreciation of the modern metering 

 devices. 



