Unsymmetrical Components in the Stark Efect. 943 



It is very unfortunate that time did not permit of further 

 experiments with a wider variety of elements and with 

 devices for the detection of radiation of other kinds. The 

 importance of a complete investigation arises from the fact 

 that the tracing of the subsequent history of the atomic 

 nucleus which has been disrupted by the collision of an 

 a-particle is, at present, one of our few paths to a knowledge 

 of the forces within the nucleus. 



In conclusion, I wish to thank Sir Ernest Rutherford for 

 giving me this very interesting problem ; and Mr. Bieler for 

 his assistance during observations. 



Cavendish Ija.bora.torv, 



Cambridge, 1921. 



0. On the Appearance of Unsymmetrical Components in the 

 Stark Effect. By A. M. Mosharrafa, £.Sc* 



§ 1. Preliminary. 



THE theory of spectral lines which has hitherto proved 

 most successful in interpreting the results of experi- 

 ment is based upon certain assumptions of a quantum type 

 introduced by Bohr f, Sommerfeld J, and others. Such 

 assumptions are only justifiable in so far as they give 

 satisfactory interpretations of correlated phenomena. The 

 effect of an electric field upon spectral lines emitted by 

 substances subjected to the field was first investigated 

 by J. Stark § in 1913 ; and an approximate theory was 

 furnished by K. Schwarzschild || and by P. Epstein if inde- 

 pendently in 1916 : the two theories are similar and give 

 satisfactory explanations of the phenomenon as investigated 

 by Stark. Now, according to their theory, the components 

 into which any given spectral line is split up are symmetrically 

 distributed about the original position of the line. In the 



* Communicated by Dr. J. W. Nicholson, F.E.S. 



t See e.q. N. Bohr, "Constitution of Atoms and Molecules," Phil 

 Mag. July 1913. 



t See Arnold Sommerfeld, ' Atombau und Spektrallinien.' IT. Auf 

 (1921). 



§ Berliner Sitzungsber., November 1913 ; Ann. d. Phys. xliii. p 983 

 (1914). 



\\ K. Schwarzschild, " Zur Quantentheorie," Berliner Sitzungsber 

 April 1916. 



51 P. S. Epstein, "Zur Theorie des Starkeffektes," Ann. d. Phys 1 

 p. 189 (1916). 



