REVIEWS 173 



that the phenomena are by no means so simple as has been represented above, 

 and it is likely that many of the statements made will be proved to be untrue " 



(p. 196). 



Again, after a spirited attack upon a particular conception of the aether and 

 certain victims of the " crudest nominalism," for whom, after all, there is more to 

 be said, the author admits that (what appears to be) the fundamental conception 

 of his book may prove "as misleading as that of the aether" (p. 317). 



No exception need be taken, within limits, to the author's standpoint, that any 

 conception is worth considering which has the merit of raising questions that 

 some older conception conceals. But many conceptions, at any rate, are mere 

 temporary expedients in the attempts at correlation of phenomena, and there is 

 the danger that excessive multiplication of conceptions, or of modifications of a 

 particular conception, in a book aiming at giving a general account of modern 

 electrical theory, will serve only to bewilder the general scientific reader. 



The author would probably admit that the book will appeal far more to the 

 expert than to any one else. Indeed, when the fundamental concept of modern 

 theory as here presented— the electron and its associated " Faraday" tube — is still 

 so elastically specified that from each electron there may proceed one tube, or 

 many, to infinity, or to infinity and back again (pp. 316, 320), it seems clear that 

 the time is not yet opportune to present the attempted correlation of phenomena 

 to such a person, if there is one, as a non-electronic physicist. For the book as a 

 means of stimulating thought and investigation by experts, however, there can be 

 nothing but praise. 



Some further remarks are suggested by perusal of the book. 



After the author's plea for exactness of expression, as on p. 313 and elsewhere, 

 one is tempted to ask how two or more tubes of like direction can pass through 

 the same point (Prop. II. p. 10). 



The statement in the middle paragraph of p. 251 — "the conclusion ... is so 

 attractive that it seems desirable to accept it provisionally " — is not a very con- 

 vincing mode of expression. 



Besides a few obvious misprints, we have noticed that on p. 25 the mass per 

 unit length is accidentally written v' 2 less than the actual value. In the interesting 

 method of exhibiting the velocity of propagation of electric effects along tubes 

 given on pp. 30, 31, the expression for V from which equation (1) is derived 

 should either contain N-' instead of N under the square root in both numerator and 

 denominator, or a necessary modification should be made in the text. 



Even if the remark were true, it seems unnecessary that the author should 

 point out (p. 254) that the "ordinary theory of chemical affinity" merely restates 

 the facts in such a way as to obscure their significance. It yet remains to be seen 

 whether the electronic or any other attempted restatement of facts may not 

 suffer, at least a little, from the same objection. In any case, the author's own 

 remark at the top of p. 255 in connection with chemical affinity, is either in- 

 complete or thermo-dynamically incorrect. 



It does not appear from the context why the author introduces the very 

 cumbrous method of accounting for Airy's experiment on the aberration of light 

 given on pp. 293, 294, and he makes the erroneous statement on p. 289 that the 

 ship and shot analogy in connection with aberration is due to Wood. It was used 

 by Airy sixty years ago or more. 



The enthusiasm of the author for his subject leads him to make more than one 

 extraordinary statement. Not the least extraordinary is : " My confidence in the 

 genius of Faraday is so great that I should be inclined to accept any hypothesis, 



