336 ILLINOIS STATE ACADEMY OF SCIENCE 



TABLE I. 



Electrode Cathode Vacuum 



Plate Voltage temperature in mm. Hg. 



710 1800 Volts 900°C 0.00001mm. 



720 1900 1150 0.00001 



730 2100 1150 0.00001 



740 Plate was a blank 



750 2000 1150 0.00001 



760 2000 1150 0.00001 



770 2050 1150 0.00001 



780 2000 1150 0.00001 



790 2000 900 0.00002 



When the even numbered circles — those taken with the 

 radiation turned on and numbered 2, 4, 6 — have a smaller 

 average diameter than the odd numbered ones — those 

 taken while radiation was off — the effect is defined as 

 positive. This decrease in the diameter of the electron 

 traces on the photographic plate is due to a collapsing 

 or a falling together of the spiral. This is caused by a 

 decrease in the velocity of the electrons in the beam. 

 The etfect is noted in the fourth column of the table 

 above. 



Another effect is present, that is, a scattering of the 

 electrons or a diffusion of the electron beam. This effect, 

 which shows mainly on the edges of the traces, can be 

 noted even when the traces are not complete circles. 

 When it is present the table indicates the fact by "yes" 

 in the last column. Plates 750 and 770 were so imperfect 

 that the effect was covered up, hence no record was made 

 for them. 



A large amount of data was also taken where radiation 

 of wave lengths from 8000 to 1300 Angstrom units fell 

 across the stream of rapidly moving electrons. There 

 were indications of a slight decrease in the velocity of 

 the electrons. This effect, however, was smaller than the 

 errors of measurement. Evidence of a scattering effect 

 when the above radiation wave lengths were used was 

 very strong. 



At the time the photographs were measured, the data 

 were put into graphical form in order that they might 

 be easily interpreted. Because the time intervals be- 

 tween exposures were approximately equal, the diame- 

 ters of the circles have been plotted as ordinates, while 



