384 Rollins — Cathode Stream and X-Light. 



the cathode stream is a repulsion between the particles of 

 residual gas in the vacuum tube and the cathode. These two 

 assertions are mentioned together, because one experiment 

 applies to both. 



An X-light tube was made with a biconcave aluminum 

 cathode in the middle of its bulb. At each end of the tube 

 was a platinum target. If the cathode stream was not affected 

 by the ether, and depended entirely upon the repulsion 

 between the cathode and the particles of residual gas, two 

 cathode streams of equal intensity should have arisen from the 

 cathode, producing the same amount of X-light at each target. 

 All the X-light arising from either came from whichever 

 target was made an anode. The experiment proved (1) that a 

 space of strained ether was necessary, X-light arising with 

 greatest intensity where the ether was most strained ; (2) that 

 the attraction of an anode was a cause of the cathode stream 

 as well as a repulsion by a cathode. 



2. The particles of the cathode stream are always given off 

 from the cathode perpendicularly to its surface ; move in 

 straight lines, coming to a focus in the center of curvature of the 

 cathode. Any one with experience can see the focus of the 

 cathode stream when well developed in an X-light tube. By 

 means of a pin-hole camera it may be photographed. Both 

 methods prove that the distance varies not only with the 

 degree of exhaustion in the tube, but also with the potential of 

 the driving current. 



I made a tube with a movable anode, whose distance from 

 the cathode could be changed by a magnet. Under the 

 conditions required for the economical production of X-light 

 it was found necessary to have the target at twice the theoreti- 

 cal distance for it to be in the focus of the cathode stream. 

 This experiment showed that the particles did not move in 

 straight lines provided they left the cathode normal to its 

 surface, nor did they come to a focus at the center of curva- 

 ture. The explanation I offered was as follows : The particles 

 of the cathode stream have the same kind of electricity, there- 

 fore they repel each other, coming to a focus beyond the place 

 required by the accepted theory. 



3. The direction of the particles in the cathode stream is 

 independent of the position of the anode at high vacua. The 

 experiment described in paragraph 1 appeared to disprove this, 

 but another is also mentioned. 



An X-light tube was made with connecting bulbs, one con- 

 taining the usual cathode and anode. In the other, encircling 

 the stem of the cathode already mentioned, as it passed 

 through this second bulb, was a ring that could be made an 

 anode. When the tube was connected in the usual way with 



