204 Prof. Townsend on the Conductivity produced in 



exceeds 10 or 20 volts. The curves show that the current 

 increases, sometimes very rapidly, after the second stage (to 

 which I have referred) is passed. 



Fig. 4. — Pressure 1*10 mm. 



160 240 



Volts per centimetre. 



720 



These experimental results are completely accounted for 

 if we consider that all ions produced by the rays, including 

 the secondary rays, are collected on the electrodes when the 

 electromotive force is small and the current independent, 



