1871.] Proceedings of the Asiatic Society. 73 
The subjoined diagram shews the connections readily :— 
J is a magneto-electric machine, the two terminals ¢ and ¢' of 
which are insulated from each other and from the ground. 
¢ is in permanent contact with a perfectly insulated leading 
wire J, long enough to reach the insulator, to the iron hood of 
which it is to be hooked. . 
¢' isin permanent connection with the clamp e to which is 
fixed a small platinum knob, m, and both the clamps, ¢ and e’, 
are permanently connected with each other. A good insulated 
leading wire, Z/, which is to be hooked on to the bracket of the 
insulator under test, is in contact with the moveable platinum 
knob m’ which, however, is insulated from ec’, when pressed down, 
but which in its position of rest, (or when not pressed down - 
short), closes the circuit between ¢ and ¢! at f. 
The whole arrangement is constructed light but strong, protect- 
ed from rain and can be carried along the line by one man only. 
