Mr. J. J/E. Durack on Lenard Rays. 



39 



and found that it kept fairly constant, it is only necessary 

 to take readings of the total current with the field in one 

 direction in order to find a p for any pressure in the hell-jar. 

 However, as it was thought that the pressure of gas in the 

 jar might alter the Lenard-ray current, ct p was found by 

 reversing the field between the plates. We then have a p 

 from the formula ± p^— 7a -| 



CCp ~dly 1 -\-y 2 j' 



10 



Curves III. 

 Discharge- tube Pressure, mm. X *0002. 



- 



X 



2 



| -10. 



6 







feT) 



^ 





- — . w 





\\ 





The curves III. have been drawn to show the saturation- 

 currents for different discharge-tube and bell-jar pressures, 

 as indicated in the following table : — 



Curve. 



Field. 

 Volts per cm. 



Bell-jar pres- 

 sures, mil). 



b 



+ 64*- 



5-2 



V 



-64 



?» 



G 



+ 110 



9-5 



c' 



-110 



5» 



d 



+ 110 



10-7 



d' 



-110 



?» 



* A + field indicates that the plate was charged positively. 



