74 



NA TURE 



[November 28, 1907 



ELECTRIC POWER AND TRACTION. 

 Electric Pozi'cr and Traction. By F. H. Davies. Pp. 



\'i + 2g3. (London: A. Constable and Co., Ltd., 



1907.) Price 6s. net. 

 ■pLECTRIC power and traction is sucli an immense 

 -'-^ subject that it is rather a bold undertaking to 

 deal with it in a small volume of 293 pages, even 

 if the reader is supposed to know the elementary laws 

 of electrical engineering. The book, however, does 

 not pretend to be a regular text-book, but it is evi- 

 dently intended for those whose knowledge of elec- 

 trical engineering is limited, and to these as well as 

 students it can be recommended. 



Four chapters deal with the generation and distri- 

 bution of power. The various systems of direct and 

 alternating current are briefly discussed, and descrip- 

 tions of typical installations are given. As the author 

 briefly touches upon the subject of direct-current 

 high-tension transmission, it is rather surprising that 

 no mention is made of the Thury system, which has 

 come into prominence during the last few years. 



Two chapters are devoted to D.C. and A.C. motors, 

 and their principles are expounded. In directing 

 attention to the starting-up of induction motors, the 

 author omits to mention the important method of 

 changing from "star" to "delta" on the stator, 

 which is used for most squirrel-cage motors up to 

 20 horse-power. 



The chapters on the application of electric power 

 are the best in the book, and the advantages of electric 

 driving are clearly brought out. On p. 124 there 

 appears a statement which shows that, in the author's 

 opinion, the time is not far distant when the voltage 

 for lighting ships will be raised to 200 or 240, but 

 this prediction will not command universal assent. 

 The modern tendency even on shore is to return to 

 no volts, especially since the introduction of metallic 

 filament lamps, and it seems more probable that 100 

 or no volts will remain the standard, voltage for 

 marine work. 



The last ten chapters of the book are devoted to 

 electric traction, and although one may find in them 

 a few statements which are open to criticism, they 

 contain a good deal of practical information. The 

 conduit and surface-contact systems are dealt with, 

 and the advantages of electric traction are briefly set 

 out. Full details are given of the direct-current 

 system in use on the Metropolitan, District and 

 London tube railways. The benefits of " multiple-unit 

 control systems " are briefly touched upon. In view 

 of the prominence given to the Westinghouse con- 

 trol system, it is surprising that no mention is made 

 of the British Thomson-Houston system, the more 

 so as the latter is in use on nearly all the London 

 tubes and underground railways. 



In his remarks on substations the author, in deal- 

 ing with motor-generators, has omitted to mention 

 Bruce Peebles' motor-converters, which in recent years 

 have come largely into use, notably on the Great 

 Western Railway, where it is the standard equipment 

 for all substations. 



On p. 240 the novel statement appears that the 

 middle rail on the Metropolitan and District railways 



NO. T987, VOL. 7/] 



is not protected, " because it is practically at earlli 

 potential." Perhaps if the author would try it, by 

 touching it, he might change his opinion. 



The exposition of the pros and cons, of three-phase, 

 single-phase, and D.C. systems is not absolutely con- 

 vincing, because, to judge from the disproportionately 

 numerous descriptions of single-phase locomotives, 

 it would almost seem that the author has an unduly 

 high opinion of this system. It might have been of 

 interest if particulars had been given of the New York 

 Central locomotives, as they represent the most recent 

 practice in D.C. traction, and surpass anything that 

 has been done, so far, with the single-phase system. 

 The book is well printed, and illustrated by excellent 

 photographs. It contains a good deal of sound prac- 

 tical information, and can be recommended to the class 

 of readers for whom it is intended. L.C. 



SCHOOL CHEMISTRY AND PRACTICAL 



ORGANIC CHEMISTRY. 



The Complete School Chemistry. By F. M. Oldham. 



Pp. viii-(-4i6. (London: Methuen and Co., 1907.) 



Price 4^. 6d. 

 Practical Chemistry for .Irmy and Matriculation Can- 

 didates. By Geoffrey Martin. Pp. viii 4-144- 



(London : Crosbv Lockwood and Son. 1907.) Price 



2s. net. 

 Systematic Practical Organic Chemistry. By G. M. 



Norman. Pp. viii -I- 98. (London : W. B. Clive, 



University Tutorial Press, Ltd., 1907.) Price 



15. 6d. 

 A Course of Practical Organic Chemistry. By 



T. Slater Price and D. F. Twiss. Pp. xiii + 239. 



(London : Longmans, Green and Co., 1907.) 



Price 3s. 6d. 

 A Scheme for the Detection of the More Common 



Classes of Carbon Compounds. By F. E. Weston. 



New edition. Pp. viii -1-95. (London: Longmans, 



Green and Co., 1907.) Price 2S. 6d. 



MR. OLDH.VM'S book provides a complete course 

 of instruction for schools. He has had in view 

 the London matriculation .and the .\rmy entrance 

 examination, but has added important sections not 

 included in either syllabus, which he says with a 

 touch of irony " should be taught wherever a teacher 

 is free from the trammels of an examination syllabus 

 and need think only of giving sound instruction." 



Judging from a general survey of the book, we are 

 inclined to think that the syllabuses above mentioned 

 were not altogether present in the author's mind 

 when he wrote it, for sound instruction is certainly 

 the keynote of his method. 



Part i. especially is excellently arranged, clearly 

 written, and admirably illustrated. If the school time 

 admitted of it one could not devise a better course for 

 the beginner in chemistry ; but the standard eventually 

 reached is far beyond that of any matriculation can- 

 didate, and one is doubtful if even three school years 

 would sufiice to cover the ground mapped out, unless, 

 indeed, the experimental part were performed for, 

 instead of by, the student, which would be a mis- 

 fortune. The programme is an ambitious one ; but 

 we believe it is thoroughly sound, and if it could be 



