December 15j 1905.] 



SCIENCE. 



787 



wMch, on account of its mathematical diffi- 

 culty no doubt, has thus far received but little 

 attention in the book literature of the electron 

 theory. This pamphlet will be welcomed by 

 all because it gives one of the foremost of the 

 world's investigators upon the mathematical 

 side of the electron theory an opportunity to 

 state the results of his work and to present 

 the present status of the theory from the 

 standpoint of the mathematical physicist. 



The last of the books which I shall mention 

 as coming from the hands of the pioneer archi- 

 tects of the structure which we now call the 

 physics of the electron, is the work of the 

 now famous discoverer of radium, Madame 

 Curie. Her thesis, entitled ' Recherches sur 

 les Substances Eadioactives ' (Gauthier-Vil- 

 lars, Paris, 1904, pp. 1-154), is a plain, con- 

 servative record of the history of this dis- 

 covery and of the most important results ob- 

 tained by both herself and others in the study 

 of radio-activity. The book, unlike Ruther- 

 ford's, is uninspired and unillumined by any 

 deep insight into the real nature of the phe- 

 nomenon under investigation, but it has the 

 inimitable charm of a simple, direct history 

 of one of the world's greatest discoveries told 

 in charmingly modest fashion by the discov- 

 erer herself. 



To turn now from the books which are pri- 

 marily for the physicist to the popular exposi- 

 tions of the work of the investigators, there 

 are none of them which do not require for 

 their intelligent reading some elementary 

 knowledge of physics ; and if such a book were 

 written it would be too superficial to be in 

 any true sense scientific, for it would have to 

 confine itself to conclusions rather than to a 

 presentation of reasons for conclusions, and 

 such statements of conclusions are almost in- 

 variably misunderstood. Among the books, 

 however, which purport to be written for the 

 general public there are two which show great 

 ability and are characterized by striking indi- 

 viduality. The first place is claimed, in my 

 judgment, by Hon. R. J. Strutt's fascinating, 

 popular treatment of ' Becquerel Rays and the 

 Properties of Radium ' (Edwin Arnold, Lon- 

 don, 1904, pp. 1-214). This is the book to 



which I should first refer the non-physicist 

 who wishes to begin the study of the newer 

 investigations which center about the physics 

 of the electron. The author says that his aim 

 has been to give as clear and simple an ac- 

 count of radio-activity as the subject admits 

 of without sacrificing accuracy. He has, 

 therefore, divorced himself entirely from all 

 mathematical modes of statement. He has, 

 nevertheless, succeeded, to a surprising degree, 

 in giving, in simple language, a clear idea of 

 the train of discovery and reasoning which 

 has led to recent conclusions. In the truest 

 sense we popularize science only in so far as 

 we succeed in putting it in such form that the 

 layman can understand, not our conclusion 

 simply, but, in a general way, the reasons for 

 our conclusions also. This Strutt has suc- 

 ceeded in doing. While his treatment is pop- 

 ular, it thoroughly vigorous, scholarly, ac- 

 curate and conservative, so that it may be 

 unlaesitatingly recommended, not only to the 

 general reader who wishes to gain a correct 

 idea of the latest aspect of scientific thought 

 in this domain, but also to the physicist who 

 wishes to gain a clearer vision of the naked 

 physical ideas which are at the bottom of, and 

 sometimes more or less beclouded by, the 

 mathematical presentation of the electron 

 theory. 



The other of the two books above referred 

 to is Robert Kennedy Duncan's new work, 

 entitled ' The ISTew Knowledge ' (A. S. Barnes 

 and Co., 1905, pp. 1-257). It is a book which 

 will generally be criticized by physicists, I 

 think, as being, to use the author's own ad- 

 jective, a trifle too ' enthusiastic ' — too Jules 

 Vernesque in its implications at least, if not 

 in its statements, to be classed as strictly sci- 

 entific; and I myself fear that the untrained 

 reader will lay it down with a somewhat erro- 

 neous impression of ' the new knowledge ' — 

 an impression that a certain quiet evolution 

 which has been going on for the last decade 

 in scientific thought is, instead, a tremendous 

 revolution; that new discoveries have over- 

 turned the cornerstones of the old faith. As 

 a matter of fact, in popular presentation, too 

 much emphasis can not be laid upon the fact 



