136 Mr Wilson, On a Sensitive Gold-Leaf Electrometer. 



To use the instrument the insulated plate is maintained at 

 a constant potential. The electrometer is placed in an inclined 

 position, as shown in the figure, the angle of inclination and the 

 potential of the plate being adjusted by trial to give the desired 

 sensitiveness. The gold-leaf being initially connected to the case, 

 the microscope is adjusted so that the image of the gold-leaf is 

 near the centre of the scale. A rise or fall of the potential of the 

 gold-leaf through a small fraction of a volt can then readily be 

 measured. 



In the experiments made to test the apparatus the plate was 

 maintained at a constant potential by means of a battery of 

 storage cells, of which one terminal was connected to the case and 



120 



100 



133 



the other to the plate. A wire leading from the terminal sup- 

 porting the gold-leaf to the sliding contact of a potentiometer, of 



