﻿On the Effect of Clouds on Ionization. 



353 



ions produced inside the chamber by the radium Rj were 

 driven to an insulated central electrode and thence through 

 an earthing key and a cut-off key to a Dolezalek quadrant 

 electrometer. 



Phil Mag. S. 6. Vol. 23. No. 135. March 1912. 2 B 



