CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL 

 LABORATORY, HARVARD UNIVERSITY. 



DISCHARGES OF ELECTRICITY THROUGH HYDROGEN. 



By John Trowbridge. 



Presented December 8, 1909. Received February 24, 1910. 



1. Reflection of cathode rays 455 



2. Striae 456 



3. The Doppler effect 462 



4. Conclusions 462 



1. Reflection of Cathode Rays. 



In the course of this paper I shall refer to certain hydrodynamical 

 analogies which the discharges of electricity through gases present ; 

 not with the conviction that in these discharges we have to deal with 

 questions of flow alone. The complicated phenomena give large scope 

 both to theories of flow and molecular theories: the hydrodynami- 

 cal analogies are more striking in discharges through gases at com- 

 paratively high pressures; 

 while molecular theories 

 apply best in highly rare- 

 fied gases. There seems 

 to be a certain continuity 

 here similar to that be- 

 tween motions of matter 

 in the liquid state and in Figure 1. 



the gaseous state, when 



such matter is subjected to forces which can produce movement or 

 flow of the particles. 



The conditions of electrical discharges in a tube represented in Fig- 

 ure 1 remind one of the flow of a fluid interrupted by a plane lamina. 

 A is a cathode, K an anode, D a diaphragm, P a plane lamina which 

 can be moved about an axis perpendicular to the plane of the paper, 

 Figure 1 being a plan of the discharge tube. P can also serve as an 

 anode. 



At the striae stage the electrical conditions in the tube are very 

 little modified by turning the lamina through small inclinations to the 



