436 POPULAR LECTURES AND ADDRESSES. 



which gives a certain result. Thus it is that a 

 velocity is the proper measure of the resistance 

 of a metallic circuit to the flow of an electric 

 current through it. 



Going now to electrostatics, the resistance of 

 an imperfect insulator to the transmission of 

 electricity along it, may be measured in a curious 

 manner in connection with the velocity. It may 

 be measured by the reciprocal of a velocity, or in 

 other words, the conducting power of a wire may 

 be measured, with reference to the electrostatic 

 phenomena, by a velocity. Thus, imagine a 

 globe in the centre of this room, at a great 

 distance from the walls. Imagine that globe to 

 be two metres in diameter one metre in radius 

 and let it be electrified, and hung on a fine silk 

 thread, perfectly dry, so as to insulate perfectly. 

 There we have a perfectly insulated globe in the 

 middle of this room. Now if you apply one end 

 of an excessively fine wire, say a wire one ten- 

 thousandth of an inch in diameter, to the globe, 

 and bring the other end of the wire to a plate of 

 metal connected with the walls of the room or 



