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VII. Notices respecting Neiv Boohs. 



Die Magneto- elektrischen und dynamoelektrischen Maschinen, by 

 Gttstav G-laser-De Cew ; and Die ElektriscJie Kraftubertragung, 

 und Hire Anivendung in der Praxis, by Edttakd Japing ; being 

 Vol. I. and Vol. II. of Harileben's ' EleJctrotechnische Bibliothek.- 

 Vienna, 1883. 



THESE little volumes are the first two of a series on electro- 

 technical subjects announced by the same publisher. Their 

 appearance is probably due to the recent rush on electric inventions. 

 The first of these volumes, dealing not only with dynamo-electric 

 machines, but also with the so-called secondary batteries and with 

 various kinds of measuring-instruments, is decidedly of the semi- 

 popular order ; though the formulae and data which it comprises will 

 doubtless be of advantage to engineers and electricians. The first 

 hundred pages are purely descriptive of the different kinds of 

 machines. Switches and secondary batteries take up another forty. 

 Pages 143 to 172 are occupied in discussing the chief mathematical 

 laws of the dynamo, including the rules for efficiency given by Sir 

 W. Thomson, and the arguments of Erolich on the equations for 

 the current. In the equations there are sundry typographical 

 errors. After this come short chapters on the construction of the 

 separate parts ; on the application to electric lighting and other 

 industrial purposes ; and, lastly, on electrical measuring-instru- 

 ments. 



The second volume possesses both the merits and the defects of 

 the first. Both are handy, well printed, clearly written; the 

 second perhaps better than the first. It begins with an argument 

 on the conservation of energy, and then describes in detail a large 

 number of forms of electric motor. A considerable section of the 

 book is given up to a description of the different kinds of cables 

 and conductors ; and another to the applications made by Deprez 

 of the characteristic curves of Hopkinson and Deprez. The author 

 appears to doubt whether a dynamo machine can be constructed 

 to give a constant potential at the terminals automatically. Secon- 

 dary batteries come in again as applied to systems of electric 

 distribution ; and the work closes with a number of examples of the 

 actual employment of electric power in Siemens's electric tramway, 

 Hopkinson's electric lift, the recent electric launches, and other 

 instances. 



An Elementary Treatise on the Planetary Theory, with a collection of 

 Problems. By the late C. H. H. Cheyne, M.A. London : Mac- 

 millan and Co. 1883. (Pp. xiv + 165.) 

 The author of this work died at Torquay, January 1, 1877, and a 

 new edition (the third) is now, at his father's request, brought out 

 under the competent editorship of the Eev. A. Ereeman, late 

 deputy Plumian Professor at Cambridge. Such being the case, 

 there is no need of a further introduction for a work which has 



