TRAVERSED BY CATHODE RAYS. 
59 
measured consisted of two chambers, A and B, each made of brass and similar in 
form to that shown in fig. 1. The two electrodes C and D were held in position by 
ebonite plugs, which closed the ends of the receivers and at the same time served as 
insulators. 
In each experiment the receivers themselves were well earthed, and also, initially, 
the electrodes C and D. As the electrostatic induction was very intense in the 
neighbourhood of the discharge tube, it was found necessary to take special 
precautions in regard to the earth connections. Wires of but very small resist¬ 
ance were used, and these were led to water mains and all the joints carefully 
soldered. 
The two chambers were separated by a disc of ebonite, and to its faces were 
attached thin brass plates, a and b. By means of wires passing out through the 
I 2 
