September 9, 1939] 



NATURE 



303 



of the free negative charge as an electron. It is 

 true that two chapters are devoted to the subject of 

 radio-activity, concerning which we read in the pre- 

 face : — 



" Sur la radioactivity de la matiere . . . nous avons 

 dit que des g^n^raliti^s. Le domaine des faits dans 

 cet ordre d'id^es est si vaste et surtout si mobile, qu'il 

 est encore tres difficile de s'y orienter. " 



Ideas at the present time in radio-activity are more 

 definite and well-grounded than in any other branch 

 of physical chemistry, but it is clear the author's 

 lack of knowledge in the recent and even the older 

 work of the subject is responsible for his views. 

 In subsequent editions this part of the work might 

 be omitted. It follows, no doubt, the precedent set 

 by Sir J. J. Thomson's well-known book on the con- 

 duction of electricity through gases ; but what was 

 natural enough when that book was written does not 

 apply to a book published in 1909. 



In the ground covered, the work does not differ 

 materially from the one just quoted and many similar 

 which have since appeared, but the treatment is in- 

 teresting and lucid, and the critical examination and 

 selection of the material chosen for presentation has 

 been done impartially and well. The lack of any con- 

 spicuous originality is compensated for by clearness 

 of exposition. In one respect, in that this is a French 

 work dealing with a scientific movement which, if 

 we exclude radio-activity, has proceeded mainly from 

 this country and from Germany, the author is at an 

 advantage, for the whole territory is surveyed in better 

 perspective in consequence. 



Both in the first part, which is of a general elemen- 

 tary character, and in the second, which deals for the 

 most part with the mathematical theory of ions in 

 physical phenomena, the author introduces his subject 

 with an excellent account of the older work on the 

 passage of electricity through ionised liquids before 

 passing on to the newer ideas which followed the 

 study of the discharge of electricity, first in high vacua 

 and later, after the discovery of X-rays and other 

 ionising agencies, in gases at various pressures. We 

 are thankful for this juxtaposition of subjects which 

 are usually regarded as independent owing to the fact 

 that the one has been largely developed by chemists 

 and the other by physicists ; but at the same time it 

 brings out the difficulties that arise when we seek to 

 apply the newer views to the case of liquid electro- 

 lytes. The two subjects have surprisingly little con- 

 nection with one another at the present time, and 

 anyone who has to teach both must be painfully aware 

 of the difficulties of harmonising them. In this book 

 the newer work on gaseous ions and their properties, 

 the various means of producing ionisation by kathode- 

 rays, X-rays, flames, &c., the re-combination and 

 diffusion of ions are discussed very thoroughly from 

 the physical point of view along regular lines. In 

 the second part an account of the electronic theories of 

 metallic conduction and of magneto-optical phenomena 

 is given, while the more metaphysical developments 

 connected with the electronic constitution of matter, 

 and the entanglement of ether by moving masses 

 NO. 2080, VOL. 81] 



are properly left to the end of the two parts 

 respectively. The book has no index, and is marred 

 by an extraordinary number of misprints, the 

 rectification of which occupies many pages of errata 

 at the end. 



OUR BOOK SHELF. 

 Problemi grafici di Trazione Ferroviaria. By P. 

 Oppizzi. Pp. viii+204. (Milan: Ulrico Hoepli, 

 1909.) Price 3.50 lire. 

 In the preface the author tells us that although graphic 

 methods are often used by the general mechanical 

 engineer, they have up to now been neglected by the 

 railway engineer. This book is intended to show how 

 such methods may be applied to the solution of nearly 

 all problems in connection with the working of trains 

 on railways. In this object the author has well suc- 

 ceeded, and it may safely be predicted that any reader 

 who has once used graphics in the very easy and 

 simple manner represented in this book will never 

 again have recourse to analytical methods. Indeed, 

 there are cases where analysis becomes so complicated 

 that its use by a busy engineer, even if he has the 

 required mathematical ability, is out of the question ; 

 as an example may be cited the acceleration diagram 

 of a train drawn by a steam locomotive. Tractive 

 effort and resistance vary in a very complicated manner 

 with the speed, and this, again, being the time integral 

 of acceleration, which in turn depends on the differ- 

 ence between tractive effort and resistance, it is easy 

 to see that a purely analytical treatment leads to almost 

 hopelessly involved formulas. Yet the author is able to 

 solve this and many other problems by his graphics 

 in a comparatively easy way, and with a degree of 

 accuracy quite sufficient for practical purposes. 



The book contains eight chapters, in which the 

 following subjects are treated : — train resistance as a 

 function of speed, weight, and type of coach and loco- 

 motive ; tractive effort of locomotives of various types 

 at various speeds, gradients, and curvature of line ; 

 speed-time-distance diagrams during acceleration; 

 possibility of making up for lost time; running down 

 long gradients and action of brakes; total time re- 

 quired for a given run ; consumption of fuel or elec- 

 trical energy and conditions of greatest economy; 

 efficiency of service. In all cases the author gives 

 numerous examples to show the application of his 

 methods to cases which are taken from practical work, . 

 and thus even a reader whose mathematical know- 

 ledge is only elementary is able to profit by this book. 

 This work should prove most useful to railway 

 engineers, and an English translation would be wel- 

 come to many. There is only one fault to find with 

 the book, and that is the very untidy appearance of 

 the diagrams. They have all "been drawn on squared 

 paper, the divisions being in millimetres. A page 

 covered closely with such lints is very tiring to the 

 eyes, and if, in addition to the multiplicity of lines, 

 there is some writing added to the curves and the 

 whole is reduced in rather a coarse way by photo- 

 graphy, the effect is by no means pleasing. It would 

 have been better if the author had omitted the milli- 

 metre divisions and retained only the lines placed a 

 centimetre apart. Gisbert Kapp. 



General Treatise of Meteorology. Part i.. Statical 

 Meteorology. By Prof. A. Klossovsky. (In 

 Russian.) Pp. xii + 642. (Odessa, 1908.) 

 The complete work will comprise four parts. The 

 two first— statical meteorology and dynamical meteor- 

 ology—will not necessitate a knowledge of higher 

 mathematics; they will form the course of meteor- 



