THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



MARCH 1900. 



XX. The Striated Electrical Discharge. 

 By J. H. Jeans *. 



Part I. 



§ 1. ri YHE present paper is principally concerned with the 

 X appearance of light which accompanies the dis- 

 charge of electricity through a rarefied gas. I have attempted 

 to show that Prof. Thomson's " Theory of the Conduction of 

 Electricity through Gases by Charged Ions " f is capable of 

 supplying an explanation of the striations, and of most of the 

 other phenomena observed in connexion with the discbarge 

 through a vacuum-tube. 



Considering the case of a one- dimensional discharge be- 

 tween two parallel and infinite plates, Thomson has arrived 

 at a differential equation connecting y, the semi-square of the 

 electric intensity at a point, with so, a coordinate measured 

 along the line of discharge. It is impossible to solve this 

 equation in finite terms, but Thomson has drawn a graph, 

 giving an approximate value of y for every value of a? this 

 graph satisfying the differential equation at every point, and 

 also the two terminal conditions at the electrodes. 



In the same paper Thomson has also given a second graph 

 in which are plotted out the result of some measurements by 

 Graham on the potential gradient in a vacuum-tube. The 

 comparison of the graph thus deduced from experiment with 



* Communicated by Prof. J. J. Thomson, F.R.S. 

 t J. J. Thomson, Phil. Mag. xlvii. p. 253 (1899). 

 Phil. Mag. 8. 5. Vol. 49. No. 298. March 1900. g 



