VIU 



Supplement to ''Nature," Alarch 5, 1908 



"prickers " of the hussar to the old flint-lock musket. 

 Putties, which Mr. \\'ebb traces back to Anglo-Saxon 

 times, are proved by recent discoveries to be as old as 

 the Mycen.-Eaa culture. 



Much, of course, still remains mysterious. Why 

 has a man's coat its buttons on the right, that of a 

 woman on the left? Is the cockade descended from 

 the chaperon headdress of the time of Richard II.? 

 Whence come the buttons on the jacket of the page 

 and on the trousers of the costermonger? Can it be, 

 as Mr. Webb suggests, that grooms weave straw in 

 the manes of horses because the horse was once 

 thought to be a corn-spirit? Such matters require 

 for their solution a wider range of induction and a 

 more scientific study of the evidence than is provided 

 by the present book, which raises, if it fails to solve, 

 many other curious problems of the same kind. 



MODERN VIEWS OF ELECTRICITY. 

 Modern Vicvs of Electricity. By Sir Oliver Lodge, 

 F.R.S. Third edition, revised. Pp. xvi + 518. 

 (London : Macmillan and Co., Ltd., 1907.) Price 6s. 



WHEN Sir Oliver Lodge decided to issue a new 

 edition of his well-known treatise, he set him- 

 self a very difficult task. The first edition was pub- 

 lished in 1S8S, the second in 1892 ; he might well 

 have thought that the dev-elopment of the science 

 during the past fifteen years had been so rapid that 

 nothing short of complete re-writing could render the 

 book deserving' of its title. However, he has concluded 

 that, since recent progress has amplified our views of 

 electricity rather than altered them, the treatise has 

 not lost its value; that it is still an expression of the 

 truth, though it may be only a partial expression. 

 Accordingly the general plan of the third edition is the 

 same as that of the first; the changes that have been 

 made consist of a few minor alterations and omissions, 

 together with the addition of six appended lectures. 



The earlier editions are so familiar that no detailed 

 comment is necessary. Electrostatic, conductive, and 

 magnetic processes are described and illustrated bv a 

 series of mechanical analogies, leading up to the 

 representation of the electromagnetic ether as a 

 medium made up of elastically connected gear wheels, 

 separated in some regions by surfaces of slip. In the 

 elaboration of these analogies the author is seen at 

 his best ; everything that he writes is extremely sug- 

 gestive, though some students may be puzzled by the 

 inconsistency between the different illustrations that 

 are used in different parts of the book to represent 

 the same action. We would direct special attention 

 to the admirable treatment of the magnetic effect of 

 materials with a permeability greater than unity. 



However, we think that the author has underrated 

 somewhat the change in even the simpler parts of the 

 work, which has been necessitated by recent dis- 

 coveries. It is true that these discoveries have 

 affected our views of the electric properties of matter 

 rather tlian the properties of electricity itself, but all 

 electrical experiments involve the use of material 

 bodies. Thus the discovery of the great difference 

 between positive and negative electricity invalidates 

 Sir Oliver Lodge's representation of the magnetic 

 NO. 2001, VOL. jy'] 



field. He can no longer account for the negative 

 result of Maxwell's attempt to find a finite angular 

 momentum in a closed current circuit by the existence 

 of two oppositely directed streams of positive and 

 negative electricity ; there must be a gyrostatic effect, 

 though it is too small to be detected by any arrange- 

 ment devised at present. 



-Again, our view of the effect of a material dielectric 

 on electrostatic phenomena has changed completelv. 

 It is not believed now that the presence of sulphur 

 alt( rs the properties of the lines of force issuing from 

 a neighbouring charged body ; the effect of the sulphur 

 on electrostatic actions should be represented in the 

 same way as the effect of iron on magnetic actions. 

 The view that all electric actions take place in the 

 medium surrounding a charged body and not in the 

 bodv itself has been modified; attention has been con- 

 centrated once more on the importance of the concep- 

 tion of a charge. It is misleading to speak of the 

 dispersion of light as obscure and to suggest that it 

 has no causal connection with selected absorption. 

 The old view that a dielectric resists the passage of a 

 current but mav be " broken down " b}' a force suffi- 

 cientlv great suggests that a perfect vacuum devoid 

 of all resisting matter should be a perfect conductor, 

 and is utterly discordant with modern views. If the 

 author did not see his way to re-write the book com- 

 pletely, we think that at least he should have added 

 copious notes on these and many similar points to 

 warn the student that the older statements must be 

 revised in the light of later knowledge. As it stands, 

 the book is of immense interest to those to whom 

 modern conceptions are familiar, for it enables them 

 to grasp at once the bearing of those conceptions on 

 fundamental problems, but it would be dangerous in 

 the early stages of reading-. 



We have detected one misprint on p. 224, 1. 24 : 

 for "infinite" read " finite." We must also protest 

 strongly against the use on p. 255 of the expression 

 " centre of gravity of the ether " in place of " centre 

 of mass." There is no evidence whatever that ether 

 has a centre of gravity. N. R. C. 



KXCL.IND AX EX.iMPLE FOR GERM.iNY. 

 Ih'r iialurieissenscliaftliche I'nterricht aiif praktisch- 

 heiirisli.scher Grundlage. By Dr. F. Dannemann. 

 Pp. xii + 3(i6. (Hanover and Leipzig: Hahnsche 

 Buchhandlung, 1907.) Price 6 marks. 



Wl^ are accustomed in matters relating to school 

 teaching to have German methods and results 

 eulogised by contrast with our own, so that it is especi- 

 ally gratifying for once to find the tables. turned. The 

 author is a leading exponent of science teaching in 

 his country, a schoolmaster of high repute in second- 

 ary schoolwork, and he has written this elaborate 

 work frankly on the model of teaching that he wit- 

 nessed at Harrow and other English secondary 

 schools; and he has produced an account which in 

 some respects is more thorough and comprehensive 

 than anything we have in England. The only work 

 to compare with it is the American book by Smith and 

 Hall which appeared two years ago, and that de.-ils 

 onlv with chemistry and physics, while Dr. Dannc- 



