with an Insulated Room. 171 



Lardner and Walker, p. 248; De la Rive, vol. i. p. 3; Ganot, 

 translated by Atkinson, p. 536. 



When, therefore^ the ordinary experiment of charging the 

 prime conductor is performed in an insulated room, according 

 to the theories which I deny, the negative electricity being 

 unable to share itself with the earth, some differences in the 

 effects produced should be attained. The negative electricity, 

 for instance, if it tends to flow to the earth, should influence 

 an electrometer placed in contact and exterior to the room. 

 Again, if the room is connected to the earth during the charging 

 of the prime conductor and is afterwards insulated, the prime 

 conductor, if touched to the room, ought not to be discharged, 

 since it can only share its electricity with the room instead of 

 with the almost indefinitely large surface of the earth. 



Now I argue that when electricity is produced, at any rate by an 

 artificial means, the negative and positive are not only always 

 produced in equal quantities, but remain each as much in abey- 

 ance as the other, and that complete discharge always consists 

 in the recombination of equal quantities of opposite electricity. 

 Thus when a conductor is charged, say, positively from a plate- 

 machine having the rubber connected to the earth, the negative 

 electricity has no tendency to flow to and distribute itself equally 

 over the earth, but distributes itself principally on the nearest 

 conducting-surfaces to the positively charged surface ; and when 

 the surface to which the negative pole is attached entirely bounds 

 the dielectric which separates it from the positively charged 

 surface, the negative electricity is entirely distributed on that 

 surface, none flowing to any other part of the earth. When these 

 are joined by a conductor, discharge occurs through the recom- 

 bination of the exactly equal quantities of electricity previously 

 produced. 



The experiment to which I allude was performed in H.M. 

 Dockyard, Keyham, where I was engaged in repairing a part of 

 the Persian-gulf cable which had been thrown overboard from 

 the ship ' Calcutta,^ and recovered and landed under my su- 

 perintendence. The insulated room was erected in the large 

 glass-covered quadrangle of the dockyard. I intended to make 

 a series of experiments, carefully recording every step. After 

 a few preliminary experiments, however, of which unfortunately 

 no record was kept, our regular work had to be suddenly pushed 

 on j and before any series of experiments could be made and re- 

 corded, the whole apparatus had to be removed. Thus I am 

 only able to write from memory ; but Mr. Herbert Taylor (one 

 of Mr. Latimer Clark^s assistants, and a well-known electrician) 

 was associated with me at the tmie and performed the expe- 

 riments with me. I have submitted this article to him, and he 

 indorses it as a correct statement of what occurred. 



