December 15, 1905.] 



SCIENCE. 



785 



SCIENTIFIC BOOKS. 



RECENT BOOKS ON THE PHYSICS OF THE ELECTRON. 



When it is remembered that the physics of 

 the electron had no recognized existence prior 

 to 1896, that it was 1898 before the corpus- 

 cular theory of cathode rays, carrying with it 

 the possibility of the divisibility of the atom, 

 had gained general acceptance, and that it 

 was 1902 before the first book appeared which 

 pretended to treat, in any systematic fashion, 

 the new class of experiments which have to do 

 with atomic ionization, or disintegration, one 

 can not suppress his astonishment at the mag- 

 nitude of the book literature which exists to- 

 day upon the general subject of the electron 

 theory. The greater part of this literature 

 is of a popular character, consisting in at- 

 tempts at the simplification and dematheraat- 

 icization of the technical books and articles 

 which the investigators themselves, for the 

 most part, write. For this reason there is 

 often so- great similarity of treatment that 

 neither the busy scientist nor the busy lay- 

 man can read it all with profit. In fact the 

 bewildering frequency of the appearance of 

 new, popular books in this field leads a re- 

 viewer in Nature savagely to remark that 

 * the time is fast coming when the qualifica- 

 tion which will play the most important part 

 in determining a man's reputation as a phys- 

 icist will be that he shall abstain from writing 

 books on the philosophy of ether, matter and 

 the universe.' For my own part, I do not 

 believe that the popular exposition of true 

 scientific knowledge can be overdone. Hence, 

 so long as the authors of new books are true 

 to the scientific spirit, and shun the inviting 

 paths of pseudo-science, I welcome each addi- 

 tion to their ranks. Since, however, the mul- 

 tiplication of books upon the same theme 

 necessitates a choice, the present collective 

 review of the book literature of the electron 

 theory is undertaken with the object of pre- 

 senting a brief characterization of the most 

 important of these books, with a view of aid- 

 ing the student of physics, whether he be 

 trained or untrained, in selecting those books 

 which best meet his immediate needs. 



It need scarcely be said that the book which 



is the fountain-head of all electron theory is 

 J. J. Thomson's ' Conduction of Electricity 

 through Gases' (Macmillan, 1893, pp. 1-560). 

 Coming as it does from the pen of the man to 

 whose genius and inspiration more than to 

 that of any other one individual, the physics 

 of the electron owes its origin and its develop- 

 ment, the book is as truly epoch-making as any 

 other which has appeared for a hundred years. 

 The student who is thoroughly familiar with 

 its content, and who has also read the same 

 author's somewhat more popular Silliman lec- 

 tures on 'Electricity and Matter' (Scribners, 

 1904, pp. 1-162, recently translated into Ger- 

 man) is in fairly good touch with the electron 

 theory as it exists to date. It should, how- 

 ever, be said that the discussion of the theory 

 in its relation to metallic conduction finds no 

 place in either of these books and that a few 

 facts have been brought to light since their 

 publication, such, e. g., as Boltwood's proof of 

 the long-suspected relationship between ra- 

 dium and uranium, which have slightly modi- 

 fied certain minor aspects of the theory. The 

 two books together are needed in order to put 

 the reader into intimate contact with J. J. 

 Thomson's views; the former in order to give 

 him, in most convenient form, both a complete 

 review of the experimental data upon which 

 the electron theory rests and the mathematical 

 analysis which it involves; and the latter in 

 order to give him a clear idea, unbefogged by 

 mathematical symbolisms, of the physical pic- 

 tures, the naked mechanisms, so to speak, 

 which are at the bottom of the author's the- 

 oretical investigations. Both books, I take it, 

 are too profound and too technical to be intel- 

 ligible to the student who has not had thor- 

 ough training in physics and mathematics; 

 although both, and particularly the latter, may 

 be read with partial understanding, and, there- 

 fore, with a certain measure of profit, by 

 workers in other fields of science. These are 

 the two books from which the popular exposi- 

 tors of recent views, from Oliver Lodge down, 

 have drawn the greater part of their material 

 and inspiration. 



The only other book the scope of which is 

 as broad as ' The Conduction of Electricity 



