NATURE 



l^2> 



THURSDAY, AUGUST 4, i5 



THREE BOOKS ON PRACTICAL 

 ELECTRICITY. 



The Poicniiovieter and its Adjunct s.'^»^y W. Clark 

 Fisher, A.M.I. C.E. Pp. x + 194. (London: The 

 Electrician Printing and Publishing Company, Ltd.) 



The Principles of Alternate Current Working. By 

 Alfred Hay, B.Sc, Lecturer on Electrotechnics at the 

 University College, Liverpool. Pp. xi -f 276 + iv. 

 (London : Biggs and Co.) 



Electric Wiring for the Use of Architects, Under- 

 7oriters, and the Owners of Buildings. By Russell 

 Robb. Pp. 183. (London and New York : Mac- 

 millan and Co., 1896.) 



MR. FISHER'S book is another example of the 

 Electrician series of technical manuals, written 

 by specialists for those engaged in electrical work. They 

 generally contain very valuable information which could 

 hardly be obtained, except by the expenditure of much 

 trouble, from any other source ; they are written with a 

 knowledge of what is important for, at any rate, the 

 practical reader, and they are illustrated in most 

 cases by well-executed drawings of instruments and 

 (nachinery. All these merits Mr. Fisher's book pos- 

 sesses. It is clear and concise, and has a distinct first- 

 hand value of its own, as the work of one who has him- 

 self made the tests and investigated most of the questions 

 which he discusses. 



The book starts off with a general description of 

 potentiometer testing, then there is a detailed account 

 t" the Crompton potentiometer, and of batteries and 

 alvanometers suitable for use in the kind of work under 

 consideration. The galvanometer which receives most 

 attention is the so-called d'Arsonval instrument. The 

 author is quite right in referring to this galvanometer 

 as a Thomson (not " Thompson," as in the text) or 

 Kelvin instrument. As a matter of fact the galvanometer 

 use of the recorder coil and magnet is, if we remember 

 rightly, explicitly referred to in the original siphon- 

 recorder patent, and several laboratory workers had found 

 the arrangement a very convenient form of galvano- 

 meter for various purposes long before "d'Arsonval 

 galvanometers " were ever heard of. 



The discussion of standards of E.M.F., and especially 

 the behaviour of the Clark cell, is one in which Mr. 

 Fisher has taken a prominent part, and the chapter on 

 this subject contains much useful information, especially 

 on the subject of the recuperative power of the cell after 

 the passage of a current through it. 



Next follow chapters on standard resistances, plali- 

 nuni-thermometry, the erection of apparatus, and the 

 Crompton potentiometer in use, all of which are very 

 valuable. Many practical details, which will materially 

 facilitate the carrying out of the tests, are given under 

 the last two heads. 



The book closes with a historical chapter and an 



account of " bridges " of different kinds. The latter 



contains a summary of the improvements of the various 



forms of bridge for low-resistance comparisons which 



NO. 1 501, VOL. 58] 



have been suggested in the course of the work of 

 Messrs. Griffiths and Callendar. 



This book shows the great advance which resistance 

 testing has made during the last seven or eight years. 

 It is apt, however, to be forgotten in these days of 

 splendidly arranged and made potentiometers that the 

 method is far from new, and is essentially that used long 

 ago by Matthiessen and Hockin in their careful com- 

 parisons made in the early days of electrical testing work. 

 The ordinary fall of potential method for the comparison 

 of resistances is the fundamental idea ; indeed, a poten- 

 tiometer method with resistance slides was in use in 

 Lord Kelvin's laboratory when the writer was there 

 fifteen or si.xteen years ago, and other arrangements, 

 depending on the same method, were employed as con- 

 venience or the work in hand dictated, without any 

 idea that they were other than obvious applications of 

 electrical principles. 



While, as we have indicated, the book is a very valuable 

 one, we should like it better if some modes of expressions 

 were modified. 



The phrase " tumbled to the fact," for instance, does 

 not seem much of an improvement in brevity or accuracy, 

 or anything else, on the older-fashioned expression 

 " grasped the fact." 



Then, again, there is here and there a suspicion of 

 smartness, which is no doubt quite superficial, but would 

 be better absent. 



The author's historical notes with respect to Poggendorf 

 {sic) are rather curious. It appears that after searching 

 English books in vain for an account of Poggendorffs 

 work, the author ultimately found the desired information 

 in a French electrical dictionary. We had thought the 

 editor (from 1824 to 1877) of i\i% Annalen der Physik was 

 fairly well known even in this benighted country; and 

 that references to his papers and an account of their 

 contents were pretty generally available in that great 

 and easily accessible work of reference, Wiedemann's 

 "Elektricitiit." .\nd, after all, the French dictionary ac- 

 count seems "to leave to desire." Poggendorff did not 

 edit the Annates de Physique et de Chemie (sic), but the 

 Annalen der Physik tind der Chemie ; with the French 

 journal Anttales de Chiviie et de Physique he had nothing 

 to do. 



These are, however, slight blemishes in Mr. Fisher's 

 book, and we hope they will be all cleared away very 

 shortly in a new edition. 



Mr. Hay's " Alternate Current Working " is a very 

 good book indeed. It gives in very moderate compass 

 an exceedingly valuable digest of most of the facts and 

 theories of alternate working which it is necessary that 

 students should know. The treatment is generally clear 

 and elegant, and well elucidated by graphical represent- 

 ation of theoretical and experimental results. 



The first chapter deals with the graphical represent- 

 ations of functions and elementary trigonometry ; the 

 second with scalar and vector quantities, simple har- 

 monic and other periodic functions. 



In the next chapter the subject proper of the book is 

 entered on, and it is then in the succeeding chapters 

 developed and discussed, in its theory and practical 

 applications, in a very complete and satisfactory way. 

 The enumeration of a few of the chief topics will give 



