﻿836 Prof. R. R, Salmi on the 



making n lines of force which intersect at a point where 

 n sheets of an equipotential surface intersect. These, again, 

 will not make equal angles with each other, but one line of 

 force will lie between every two consecutive sheets of the 

 equipotential surface. 



Fig. 2. 



The Intersection of Three Lines of Force and Three Sheets of an 

 Equipotential Surface. 



The cases when two and three sheets intersect are shown 

 in figs. 1 and 2. The firm lines represent the equipotentials 

 and the broken lines the lines of force. 



LXXXVIL The Photographic Action of a, /3, and y Rays. 

 By R. R. Sahni, M.A., Professor, Government College, 

 Lahore *. 



[Plate XII. ] 



SEVERAL investigators have studied the action of 

 a particles on sensitive films. Thus, Kinoshita f has 

 shown that when such a film is exposed to an a-ray source, 

 the photometric density of the film, on development, is 

 proportional to the number of a particles incident on it ; 

 also that a single a particle produces a detectable effect on 



* Communicated by Sir E. Rutherford, F.K.S. 



f Kinoshita, Proc. Roy, Soc. ser. A, lxxxiii. p. 432 (1910). 



