428 



Mr Waran, On the ejfect of a tnagnetic field 



On the effect of a magnetic field on the intensity of spectrum lines. 

 Bj H. P. Waran, M.A., Government of India Scholar of the 

 University of Madras. (Communicated by Professor Sir Ernest 

 Rutherford, F.R.S.) 



(Plate III.) 



[Read 16 May 1921.] 



Since my last communication to the society* on the pheno- 

 menon of the changes in the general spectrum brought about by 

 the influence of the magnetic field, I have come to know that the 

 phenomenon has been noticed as early as 1858| and studied to a 

 certain extent by various observers. Yet the complex changes 

 taking place in the source when the radiation is emitted from 



Fig. 1. 



inside a magnetic field, does not seem to have had the attention 

 it deserves. But in 1913J Messrs Kent and Frye made a study of 

 the phenomenon in some particular cases with a view to its com- 

 plete elucidation. They do not seem to have come to any definite 

 conclusions and from their experiments they seem to be inchned 

 to attribute the effects observed mainly to the chemical disinte- 

 gration of the walls of the discharge tube brought about by the 

 disruptive action of the blast of ions deflected to the sides by the 

 magnetic field. 



Considering a section of the discharge transverse to the mag- 

 netic field, as in Fig. 1, with the lines of force entering the plane of 



* Proc. Camb. Phil. Soc. vol. 20, Part i, p. 45. 



t A. de la Rive, Annales de chimie et de physique (3), 54, p. 238, 1858. 



% Astrophysical Journal, 37, pp. 183-189, 1913. 



