580 



SCIENCE 



[N. S. Vol. XXIX. No. 745 



second year of his work in physics, immedi- 

 ately after the completion of a course in gen- 

 eral physics, and to give him a thorough 

 course in the principles of mechanics stated 

 in the language of the calculus and vector 

 analysis, but emphasizing the physics of the 

 subject. The statement of physical facts and 

 concepts in mathematical language is one of 

 the difficult steps in a student's course; and 

 Professor Crew has done well in giving us his 

 introductory course in the mathematical side 

 of physics. 



The book is written in a style which is al- 

 ways clear and interesting. The forms of 

 statement are fresh, and the author has drawn 

 on a wide range of reading and experience 

 for new and apt illustrations. 



A. P. Carman 



The Evolution of Forces. By Gustave LeBon. 



Pp. 388. New York, D. Appleton & Co. 



1908. 



In the controversy between Mr. Norman 

 Campbell, of Trinity College, Cambridge, and 

 Mr. F. Legge, of the Eoyal Institution, con- 

 cerning Dr. LeBon's writings, Mr. Campbell 

 said: 



I was a student of that author's works two 

 years before his book appeared, and I believe that 

 I have read every word that he has ever published 

 on physical questions.* 



On the basis of this thorough knowledge. 

 Dr. Campbell places an extremely low esti- 

 mate upon LeBon's work. 



I have not read all of LeBon's writings by 

 any means, but very certainly the present book 

 on " The Evolution of Forces " is of little or 

 no account, except in one respect only. If one 

 wished to diagnose the ills of contemporary 

 French science, one would find in LeBon ex- 

 aggerated symptoms of a malady (not of 

 course affecting all French scientists) which 

 has resulted from the tremendous' scientific 

 preeminence of the French during the early 

 part of the nineteenth century. Let one con- 

 sider the state of mind of a man who can ex- 

 press himself after the manner of the follow- 

 ing quotations which are taken almost at 

 random from LeBon's book: 



'The Athenwum, March 3, 1906. 



This happy confidence in the great dogmas of 

 modern science remained unaltered imtil the quite 

 recent date when unforeseen discoveries condemn 

 scientific thought to sruffer doubts from which it 

 imagined itself forever free. 



There should, therefore, be no hesitation to 

 examine closely the fundamental dogmas of sci- 

 ence, for the sole reason that they are venerated 

 and at first sight appear indestructible. 



After I had proved that the dissociation of 

 atoms was a imiversal phenomenon and that mat- 

 ter is an immense reservoir of energy hitherto 

 unsuspected in spite of its colossal grandeur, etc. 



Speaking of a certain matter, LeBon says: 



As I expected, it was one of those classic errors 

 repeated without verification to which repetition 

 at length gives indisputable authority. 



Speaking of amother matter, he says: 



All authors have regarded it as having a pre- 

 ponderating infiuence. 



There is one idea which, according to my 

 experience, seems to be dominant in the minds 

 of young students, namely, that the physical 

 science which they study in the technical 

 school or college is in the text-book and was 

 created by a literary effort of an author. Dr. 

 LeBon, apparently, has never got beyond 

 this childish idea. The word author, as ap- 

 plied to a scientist, is misleading. Our scien- 

 tific men in the United States do not combine 

 sufficiently the ability to write with the abil- 

 ity to search and search again, so that, al- 

 though it is mildly ridiculous to call many of 

 them authors, it would be a distinct affront to 

 speak of them narrowly as such. 



W. S. Franklin 



Contribution, toward a Monograph of the 

 Lahoulbeniaceae. By Eoland Thaxter. 

 Part II. With 54 plates. Memoirs of the 

 American Academy of Arts and Sciences, 

 Vol. XII., No. VT. 4to, pp. 219-461. 

 Cambridge, printed by Edward W. Wheeler. 

 June, 1908. 



Nineteen years ago Dr. Thaxter published 

 his first paper on the Lahoulbeniaceae,' and 

 since that time has brought out many papers 

 in which he has steadily added much to our 

 knowledge of the species and genera and still 

 * " On Some Species of North American Lahoul- 

 beniaceae," Proe. Am. Acad. Arts and 8ci., Vol. 

 XXIV., February, 1890. 



