THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[SIXTH SERIES.] 



JUL F 1917. 



77 



I. A new Determination of e, N, and Related Constants* 

 By R. A. Millikan *. 



1. Introductory. 



THE only preceding determination of e and N for which 

 a high degree of precision has been claimed was- 

 completed in 1912 and published in full in 1913 t- This 

 determination yielded, for the electronic charge and the 

 number of molecules in a gram-molecule, the following 

 values : — 



e = 4*774 xlO" 1() + -0095 electrostatic unit, 

 N= 6-062 xlO 23 +-012. 



Although these values, as well as the method by which 

 they were obtained, received quite general recognition, it 

 soon became imperative to reopen the problem and to 

 attempt to make a new and, if possible, more convincing 

 determination. 



For, first, Professor Ehrenhaft and his pupils began 

 publishing in 1914 \ a series of results which, though 

 obtained by a modification of my method, were wholly 

 irreconcilable with the results which I had found. I wished,, 

 therefore, to see whether I could check their conclusions and 

 find conditions under which my method failed. 



Secondly, there developed a tendency, especially among 



* Communicated by the Author. 

 f Physical Review", ii. pp. 109-143 (1913). 



t Ann. der Physik, xliv. p. 657 (1914), xlvi. p. 261 (1915) ; also Phys. 

 Zeit. xvi. p. 10 (1915). 



Phil. Mag. S. 6. Vol. 34. No. 199. July 1917. B 



