Vol. X, No. 6 ] Measurements with Quadrant Electrometers. 229 

 W.8.] 



cylinders are adjusted so as to dip when necessary into metal 

 cups containing mercury, which are carried by stout wires, 

 entirely in air, or through small sulphur plugs, from the other 

 parts of the apparatus. The key thus amounts to an ordinary 

 four-way key in permanent connection to one pair of quadrants, 

 with lateral and diagonal connections which can be operated 

 from a distance by threads. Practically the whole of the insula- 

 tion of this key is thrown on the ambroid insulators of these 

 quadrants, and as it can be enclosed in the same case as the 

 electrometer no separate drying agent is necessary 



Simple adjustments are added to centre the points of the 

 cylinders in the mercury cups, and to prevent breaking the 

 suspensions by sudden jerks. 



The connections are shown in the diagram. 



•a 



A 



T 



V 



