November 9, 1905] 



X.I TURE 



with the subject of trapping and snaring, we may 

 take occasion to remark that the agitation which has 

 been set on foot in this country against traps of an 

 unduly cruel nature (indeed, against " gin-traps " of 

 all kinds) does not appear to have reached the other 

 side of the Channel, or, at all events, does not seem 

 to have had any effect there. For in the present 

 volume there is a cut of an unfortunate falcon 

 ensnared in one of the abominable pole-traps, without 

 a word of condemnation of snares of that description 

 (unnecessarily cruel from the fact that they are in 

 many cases only visited at long intervals). 



The volume commences with a series of chapters 

 pointing out the commercial importance of " la 

 chasse," first as a source of revenue to the State, 

 thin as a source of food-supply, next in connection 

 with rendering unfertile tracts profitable, and finally 

 in relation to the rural population. The second 

 section of the volume is devoted to game protection 

 and the natural and artificial rearing of game birds, 

 in the course of which the English and French 

 methods of pheasant breeding are contrasted and their 

 relative merits compared. Sporting dogs — other, of 

 course, than hounds — form the subject of the third 

 section, which is illustrated with a number of cuts 

 1 mil b) any means always of the best) of some of the 

 chief breeds, and the manner of training dogs for 

 their special duties. Then comes a dissertation on the 

 various methods of destroying animals commonly 

 classed as injurious to the game-preserver and the 

 agriculturist, in the course of which, as already 

 mentioned, every kind of trap and gin, no matter 

 how cruel, is described in detail, while the reader is 

 also instructed in the various methods of employing 

 tire-arms and poison for the same end. The more 

 legitimate forms of sport, including, however, small- 

 bird-shooting and rabbit-netting, together with an 

 account of the legislation connected with the subject, 

 form the concluding sections of the volume. The 

 whole subject of " la chasse " or " le sport " is viewed 

 mi differently by our French neighbours and by our- 

 selves, that it is somewhat difficult to give an un- 

 biased opinion on the merits of the volume before us. 

 Probably, however, it is thoroughly well suited to the 

 class of readers for whom it is specially intended, 

 although we cannot but regret that an attempt was 

 nut made to inculcate more humane views in the 

 matter of the destruction of so-called noxious animals. 



R. L. 



OUR BOOK SHELF. 

 Ergebuissc und Vroblcmc dcr Elektronentheorie. Bv 



Prof. H. A. Lorentz. Pp. 62. (Berlin : J. Springer, 



1905.) 

 I ins book contains a lecture given by Prof. H. A. 

 Lorentz before the Elektrotechnischen Verein at 

 Berlin, December, 1904, to which certain additions 

 have been made. It is a most interesting semi- 

 popular account of the present position of the electron 

 theory, which is due largely to the author. 



The lecturer begins with a short historical intro- 

 duction, and then goes on to discuss the properties 

 ol kathode rays, which, of course, are negative 

 electrons. He describes the methods by which the 

 ratio of the mass to the charge of these ravs has been 

 NO. 1880, VOL. J 3] 



determined, and Kaufmann's beautiful research on 

 the $ rays from radium, which, in conjunction with 

 J. J. Thomson's and Abraham's theoretical investi- 

 gations, has led to the conclusion that the mass of 

 these rays or electrons is entirely electromagnetic in 

 its origin. 



The most interesting part of the lecture now 

 follows, where a description is given of the electron 

 theory of the conductivity of metals. The beginnings 

 of the electron theory of metallic conductivity we owe 

 to Weber and Kohlrausch, and its recent develop- 

 ments to Riecke, Drude, and J. J. Thomson. Lorentz 

 here adopts J. J. Thomson's view, that the con- 

 ductivity of metals is entirely due to the presence in 

 them of freely moving negative electrons, and that 

 the positive electrons are practically fixed, and so do 

 not contribute to the conductivity. Riecke and Drude 

 have so far supposed that both the positive and 

 negative electrons move. The lecture contains an 

 interesting discussion of the special difficulties of these 

 rival hvpotheses, neither of which has yet been made 

 to fit in with all the facts. 



According to the electron theory of metallic con- 

 duction, the electrons move about between the metal 

 atoms so that they are practically in the gaseous 

 condition and the results of the kinetic theory of 

 gases can be applied to them. On these assumptions 

 the ratio of the conductivity for heat to the electrical 

 conductivity can be calculated, and the result is that 



" 3W 



T, 



where fe=heat conductivity, <r = eleetrical conductivity, 

 T = absolute temperature, e = charge carried by one 

 electron, and a = the gas constant. According to this 

 equation, kicr should be the same for all metals and 

 proportional to the absolute temperature. The experi- 

 mental results so far obtained agree on the whole 

 very well with these conclusions, and form a striking 

 confirmation of the general truth of the theory. The 

 observed absolute value of kja- also agrees fairly well 

 with that calculated by means of the formula just 

 given. 



The electron theory also gives a fairlv satisfactory 

 explanation of the phenomena of thermoelectricitv and 

 contact potential difference, but it is very difficult to 

 reconcile completely with the facts on the Hall effect. 

 H. A. Lorentz's lecture shows that many problems of 

 the electron theory still await a solution, but it also 

 shows the immense progress which has recently been 

 made, and suggests the idea thai very soon nothing 

 but ether and electrons will be retained in our concep- 

 tion of the physical universe. H. A. Wilson. 



Die elektrischen Bogenlampen, deren Prinzip, Kon- 



struktion und Anwendung. By J. Zeidler. Edited 



by Dr. G. Benischke. Pp. x+143. (Brunswick: 



Friedrich Vieweg und Sohn, 1905.) Price 5.50 



marks. 



The book published under the above title forms the 



sixth pamphlet of " Elektrotechnik in Einzel- 



Darstellungen." The author divides the contents 



into four parts. In the first one he shows great 



ingenuity in classifying lamps; he also explains the 



actions of series, shunt, and differential arcs, and 



describes the precautions which are necessary to 



ensure steady burning. 



In the second part we find the constructions of 

 various types of arc lamps, the sizes of carbons to 

 be used, the advantages and disadvantages of flame 

 and enclosed arcs, and an article on inverted lamps. 



The third part deals with the distribution and calcu- 

 lation of light. It describes the construction of polar 

 and Rousseau curves, the meaning of hemispherical 

 intensity, the power-factor of alternate current flame 



