October 16, 1896.] 



SCIENCE. 



579 



machine than others, it is, on the whole, unex- 

 celled by any. 



Since the issue of the first edition many in- 

 ventions and improvements in this class of en- 

 gine have been made, and the oil-engine, par- 

 ticularly, has been enormously perfected and 

 widely introduced. The author has introduced 

 into this edition two additional parts, has dis- 

 cussed the modern gas-engine more fully in 

 the second part, and has devoted the third 

 part entirely to the now well-established forms 

 of oil-6ngine. He has drawn largely from his 

 personal experience in this work, and has given 

 a very thorough and remarkably judicial dis- 

 cussion of the merits, absolute and relative, of 

 existing and commercially successful types and 

 forms. Appended to the text is a complete 

 list of British patents, from 1791 to its date, 

 which will be found by the professional reader 

 an exceeding valuable feature of the book. 



The illustrations have been reproduced from 

 working drawings and by expert draughtsmen. 

 The originals have been obtained from many 

 prominent makers as well as from the author's 

 own portfolios. 



The practical value of the work is, perhaps, 

 best indicated by the fact that it has been trans- 

 lated into foreign languages and is adopted as 

 a reference and text-book by many technical 

 schools and colleges. For this latter use it is 

 particularly well-adapted by its thoroughly 

 logical form and exceptionally scientific meth- 

 ods. The author is entitled to the hearty 

 thanks of all who are interested in his subject, 

 and the publishers are no less deserving of 

 credit for their admirable and conscientious 

 work in making up the book. It is well-written 

 and well-published, and will be found a real 

 accession to every engineer's library in which 

 it may find a place. It may well be questioned 

 if any other work on this subject will prove 

 more generally useful. R. H. Thurston. 



Ithaca, N. Y. 



SCIENTIFIC JOURNALS. 

 PHYSICAL REVIEW, VOL. IV., NO. 2, SEPT.-OCT. 



The Velocity of Electric Waves: By C A. 

 Saunders. In this article Dr. Saunders de- 

 scribes experiments by which the velocity of 



electric waves traveling along wires was directly 

 determined. The method involved the meas- 

 urement of the length of stationary waves de- 

 veloped on long copper wires, and at the same 

 time the determination of the frequency of these 

 waves. The latter determination was made by 

 photographing the oscillatory spark from which, 

 the waves in question originated. The method 

 used seems quite similar to that employed by 

 Prof Trowbridge and Mr. Duane, and the re- 

 sults indicate about the same value for the ve- 

 locity, viz., from 2.954X10'° cm. per sec. to 

 2.998X10'° cm. per sec. The method used 

 is seen to be a direct one, and does not de- 

 pend upon any assumption regarding the man- 

 ner in which the oscillations are set up. The 

 close agreement obtained between the velocity of 

 electric waves and velocity of light is for this 

 reason especially satisfactory. 



On the Measurement of the Expansion of Metals 

 by the Interferential Method, II.: By E. W. 

 MoRLEY and W. A. Eogbrs. In the first part 

 of this paper the general outline of the method 

 used, as well as many of the important practical 

 details, were discussed. In the present article 

 the numerical data are given for a test of the 

 method, and the computations of the results 

 are presented. Using a bar of Jessop's steel, 

 the authors find for the coeflBcient of expan- 

 sion between the temperatures of and 65° 

 a value of 10.45//. This result compares 

 quite favorably with the values 10.58 and 

 10.51 obtained by other methods! The 

 authors do not consider, however, that the 

 method has been given a fair trial, since a 

 series of accidents caused the temperature 

 measurements to be far less accurate than was 

 to be desired. 



An Experimental Study of Induction Phenomena 

 in Alternating Current Circuits : By F. E. MiL- 

 Lis. In the present article Dr. Millis has de- 

 voted his attention especially to the phenomena 

 of charge and discharge in condenser circuits, 

 making use of the alternating current galva- 

 nometer previously described by himself and Mr. 

 Hotchkiss. The current curves for charge and 

 discharge, under a variety of conditions, have 

 been photographed. The needle used, which 

 was so light as to follow the variations in cur- 



