Mr Wilson, On a Portable Gold-leaf Electrometer, etc. 185 



The actual form of the instrument is shown in the figure, 

 which is drawn approximately to scale. 



The outer case is a short brass cylinder 4'6 cms. in diameter, 

 the ends being closed by vertical glass plates ; the distance from 

 back to front is 3 cms. The inner case is concentric with the 

 outer, and is 2*5 cms. in diameter and 22 cms. from back to front. 

 The ends are again closed by glass plates. The glass plates of 

 both inner and outer plates are silvered internally, a horizontal 



