5 14 Notices respecting New Boohs. 



modem or surname Geometry acceptable to English students. On 

 p. 385 there is a too general statement which requires correction 

 (see first five lines). 



(iii.) "We like this second instalment of the Elements better 

 even tban we liked the previous one. Mr. Taylor's treatment in 

 parts differs from that of other writers, there being a good deal 

 of rearrangement in the first twelve propositions, but the matter 

 treated of agrees in substance with that given in Euclid's first 

 twelve propositions. Ptolemy's theorem (the so-called Euc. vi. d) 

 comes in as Prop. 37 b, being prefaced by Prop. 37 a. There is 

 also an interesting additional proposition which involves the prin- 

 ciple of the rotation of a plane figure about a point in its plane. 

 There are also some propositions on Poles and Polars, on Radical 

 Axes, on Orthogonal Circles, and on the Nine-point Circle of a 

 Triangle. The carefully selected examples are a valuable feature 

 of a good elementary edition of the ' Elements.' 



(iv.) The idea of this capital [little book of Eiders is : " first a 

 deduction is worked out in full, w T hich is intended to serve as a 

 model for the student. This is followed by a number of similar 

 deductions, which are to be written out by the student, the figure 

 being given in each case, and such hints regarding the mode of 

 solution as experience shows are required by beginners. Lastly, 

 each section contains some deductions to be accomplished without 

 this aid, no figures or assistance being given except an occasional 

 reference to the proposition on which the proof depends, or to a 

 previous example." It will be thus seen that the idea is an excel- 

 lent one for the majority of young students, and it is very well 

 carried out. The abundance of good figures is a strong feature. 

 After working through all the exercises we can strongly recommend 

 the book, the only drawback that we see being that few can give 

 so much time to the thorough getting up one book of the Elements 

 as is involved in working out all the deductions. The student, or 

 his teacher for him, must make a selection if he has not time. This 

 we think we can guarantee, that when he has worked through this 

 collection, he will make short work of the major part of the 

 deductions which he will meet with in ordinary school examinations. 



Die Elektrischen Verbrauchsmesser — Electricity Meters. By Etiekne 

 de Fodoe. (Leipzig: A. Hartleben.) 



The series of which the present volume forms a part contains 

 some excellent treatises on various subjects connected with electro- 

 technics written by competent continental specialists. It is 

 greatly to be regretted that they are not accessible to the majority 

 of English readers on account of their being written in German. 

 So far as we are aware only one of them (viz. Tumlirz on 

 Potential) has been translated into English ; but it would well repay 

 any one who can spare the time to make translations of some of 

 the other volumes, and certainly of the one before us. 



The problem of the measurement of electricity for commercial 

 and domestic purposes is one which so far has only been very un- 

 satisfactorily and incompletely solved, although the demand for 



