308 ILLINOIS STATE ACADEMY OF SCIENCE 



We see from this table that in order to get a galvano- 

 meter deflection of about 27mm. the equivalent current 

 flowing through our cathode ray solenoidal beam must have 

 the value of .1 ampere, while .005 ampere will give a de- 

 flection of only 1 mm. Intermediate values of I give 

 intermediate deflections. Obviously, the current must ex- 

 ceed .005 ampere in order to be detected, and to be measured 

 with fair accuracy the current flowing through the beam 

 should be of the order of .05 ampere. 



Two methods are available for the interruption of the 

 cathode ray beam. The simplest, from a manipulative 

 standpoint, is to break, at some external point, the high 

 potential direct current supplied to the hot lime cathode. 

 However, the most effective and theoretically correct method 

 is to interrupt the beam by a shutter just before it enters 

 the tube on which the secondary is wound. This shutter 

 is operated from the outside through a ground joint. The 

 general arrangement of the various connections is shown 

 in Fig. 1. 



In this preliminary report we may say that the order of 

 magnitude of the cathode ray current that we were able to 

 get in the few trial runs thus far made was about .005 am- 

 pere, — thus the effect was just detectable. We expect to 

 increase the current flowing through the electron solenoid 

 at least ten times, by using a larger source of electrons and 

 also by introducing hydrogen into the tube. When this is 

 done no difficulty will be experienced in measuring quan- 

 titatively the effect sought. 



Department of Physics 

 University of Illinois 

 April 27, 1921. 



