1920. ] Measuremenis with Quadrant Electrometers. 21 
due to moisture on the surface of the latter as well as conduc- 
tion would be entirely eliminated. By reversing the potential 
of the guard cylinder this leakage effect should be doubled, 
the quadrants, and since the potential of the wire passing 
through the sulphur plug is never higher than this and is 
usually lower, the leakage due to moisture and conduction is 
employed to reduce the leak of the whole system consisting of 
the quadrants connected to the wire 
The following table, showing result of observations taken 
with the guard-ring, indicates the very great om rebebang 
effected in the insulation of the sulphur “plug even during t 
monsoon. Of the observations taken on the 21st of Xoeuit, 
1919, Column D shows the rates of leakage of the quadrants 
alone. Column C shows that the rates of leakage of the 
quadrants with the sulphur plug having its guard-ring properly 
guard-ring or by putting the opposite potential on it. Similar 
results were obtained on the next day with a positive charge 
on the quadrants, and the airocniett between the Columns 
and B is as satisfactory as before. 
