300 



SCIENCE. 



[N. S. Vol. I. No. 11. 



larly if it is not attempted to cover all 

 branches, is a far more practicable problem, 

 as the success of this volume demonstrates. 



A work of this kind, however, is some- 

 what limited in its scope, since it is not in- 

 telligible to the ordinary untechnical reader, 

 and is not of much use to the professional 

 electrical engineer, who requires a more 

 thorough and detailed study of each sub- 

 ject than is possible in a general treatise. 

 This work would therefore be suited to one 

 who had a certain amount of technical 

 knowledge but who was not a specialist in 

 electricity, for example, a mining or me- 

 chanical engineer, or a young man who had 

 received a certain amount of electrical edu- 

 cation at a technical or trade school and 

 who wanted to learn more by his own ef- 

 forts. It would also be useful as a text- 

 book wherever a general course in electric- 

 al engineering is given. But in the opin- 

 ion of the reviewer, a general treatment 

 running from one subject to another is not 

 the best way to educate electrical engineers 

 of the highest type. This requires a care- 

 ful and special study of each branch, aided 

 by lectures and laboratory work, and the 

 text-books should be entirely devoted to 

 one subject, or, in fact, several books, each 

 devoted to a small part of any one branch, 

 is often preferable. 



The authors of this book have had con- 

 siderable experience as teachers and also 

 the advantage of correcting and extending 

 the contents of the first edition, which ap- 

 peared in 1890, with the result that the new 

 edition is well arranged and expressed and 

 in most cases is brought reasonably well up 

 to date. The first six chapters are devoted 

 to general principles, units and methods of 

 measurement. The next six chapters con- 

 tain a treatment of dynamos and motox's 

 which is very satisfactory, considering the 

 limitation of space. Transformers, second- 

 ary batteries, arc and incandescent lamps, 

 are also well explained ; but the last chap- 



ter, on ' Installation equipment, fittings, 

 etc.,' is very meagre and the least satisfac- 

 tory portion of the book. In fact, the prin- 

 cipal criticisms would be that each element 

 or device is explained as a separate thing, 

 and no methods for combining these into 

 systems are given. Nevertheless, it is a fact 

 that the general design and arrangement of 

 electrical apparatus is fully as important as 

 the merits of each particular element. For 

 example, the laying-out of a centi-al station, 

 or even a small isolated plant, determines 

 its success or failure fully as much as the 

 quality of the individual dynamos, lamps, 

 or other particular parts of the plant. 



The various systems for transmitting and 

 distributiug electric power, which is prob- 

 ably the most important branch of electrical 

 engineering, are barely touched upon. In 

 short, we may say that electrical engineer- 

 ing in its broadest sense is not covered, and 

 probably was not intended to be covered, 

 by this work. The subjects of electro-chem- 

 istry and electro-metallurgjf, which now 

 appear to be on the eve of important de- 

 velopment, are not discussed. Telegraph 

 and telephone apparatus and methods are 

 not even mentioned. 



These omissions, which are doiibtless 

 intentional and probabty necessary, indicate 

 that a complete treatise on electricity and 

 its applications is almost an impossibility. 



A few mistakes are noted ; for example, 

 on page 17, the International Ohm, adopted 

 at the Chicago Electric Congress of 1893, is 

 defined iu terms of a column of mercm-y 

 106.3 centimetres in length and one square 

 millimetre in cross section, whereas, the 

 statement actually adopted was ' a column 

 of mercury at the temperature of melting 

 ice, 14.4521 grammes in mass, of a con- 

 stant cross-sectional area and of the length 

 of 106.3 centimetres.' This was intended 

 to be exactly equivalent to a cross-section 

 of one square mm., but it was put in this 

 form because mass is more easily and ac- 



