378 



Prof. Owens on Thorium Radiation. 



fig. 9 were obtained. The plates were 1 cm. apart, and the 

 lower plate charged to 95 volts. The current at atmospheric 

 pressure was taken as 100. It will be seen that the current 



Fig. 8. 



^ 



S 



-R 



I- 



increased directly with pressure up to about 300 mm., reached 

 a maximum at about 600 mm., and gradually diminished to 

 about one-third of its maximum value at a pressure of 

 2786 mm. 



The result is quite in agreement with what the general 

 considerations above indicate. 



The effect of varying the distance between the plates, as 

 well as the gas-pressure, is shown in Tables VIII a, VIII b, 

 and VIII c, and on fig. 10. Pressures above an atmosphere 



