SECTION C PHYSICS OF THE ELECTRON 



(Hall 5, September 22, 3 p. m.) 



CHAIRMAN: PROFESSOR A. G. WEBSTER, Clark University. 

 SPEAKERS: PROFESSOR PAUL LANGEVIN, College de France. 



PROFESSOR ERNEST RUTHERFORD, McGill University, Montreal. 

 SECRETARY: PROFESSOR W. J. HUMPHREYS, Mount Weather, Va. 



THE RELATIONS OF PHYSICS OF ELECTRONS TO OTHER 



BRANCHES OF SCIENCE 



BY PAUL LANGEVIN 

 (Translated from the French by Bergen Davis, Ph.D., Columbia University) 



[Paul Langevin, Assistant Professor of Physics, College de France, Paris, since 

 1903. b. Paris, France, January 23, 1872. Licencie" in Physical and Mathematical 

 Science; Fellow of the University; Ph.S.D.; Instructor at Sorbonne, 1899- 

 1903.] 



THE remarkable fertility shown by the new idea, based on the 

 experimental fact of the discontinuous corpuscular structure of 

 electrical charges, appears to be the most striking characteristic of 

 the recent progress in electricity. 



The consequences extend through all parts of the old physics; 

 especially in electromagnetism, in optics, in radiant heat; they 

 throw a new light even on the fundamental ideas of the Newtonian 

 mechanics, and have revived the old atomistic ideas and caused 

 them to be lifted from the rank of hypotheses to that of principles, 

 owing to the proper relation which the laws of electrolysis have 

 established between the discontinuous structure of matter and that 

 of electricity. 



Without seeking here to run through the whole field of their appli- 

 cations, I hope to indicate upon what solid foundations, both experi- 

 mental and theoretical, rests at present the notion of the electron so 

 fundamental to the new physics; to indicate the points which seem 

 to require more complete light, and to show how vast is the synthesis 

 which we can hope to attain, a synthesis whose main lines only are 

 fixed to-day. 



Under actual and provisional form, this synthesis constitutes 

 an admirable instrument of research, and owing to it the questions 

 extend in all directions. There is there a kind of New America, full of 

 wealth yet unknown, where one can breathe freely, which invites 

 all our activities, and which can teach many things to the Old World. 



