§4 AEfilAL COLUM:^ and AEKIAL EIECTROSCOFE. 



^' mities of the column, then positive at A, and negative at B j 

 *• there is no divergence in the electroscope C ; it is a neutral 

 '' pointj and is expressed by in TABLE I. If, at the same 

 "time, any point of the co/«wn, at a distance from the point 

 " C, on the negative or positive side, proportional to one of 

 " the terms of table I, be tried by the insulated wire, the di- 

 *' vergence produced is, as exactly as can be expected in such 

 " experiments, correspondent to that expressed in the tat/e, 

 with its sign either — or +." 



7. In Exp. 8 are seen the two different cases expressed in 

 TABLES II and III, observed also by means of the insulated wire. 

 The case of table II is produced by placing the end B, or wff- 

 gative, in communication with the ground. In this case, the 

 electrometer at the middle point C, which, in the preceding 

 case, was neutral, has a positive divergence, equal to that before 

 , observed at the extremity A, where it is now double. Ther® 



\s no neutral point perceptible, but close to the end B, whence 

 the positive state is increasing towards A, at the rate expressed 

 by TABLE II. If the communication with the ground be in- 

 versely placed at A, or ihe positive extremity, which is the cas« 

 of TABLE III ; then the only point found neutral in the column, 

 I is close to that end A ; and thence the negative state is increasing 



up to B, where it is become nearly double ; and at the middle 

 point C, the divergence, nov/ become negative, is equal to what 

 it is at the extremity B, when the column is insulated. 

 Tlie effecte 8' I^ Dr, Maycock had known these experiments, in which 



produced the electroscopes indicate, to the eye, the motions of the 



uilsareiucou- ^^^'-"^^'^-Z^^^^'^^" ^^^ ^''^"^"j ^^ <^°^^*^ ^^^ ^^^^'® persisted in hia 

 ti*C'^- opinion, that the metals do not produce their electrical effects 



while in contact, and only at the instant they are separated ; for 

 they were not separated an instant during the course of these 

 experiments. Besides, I am induced to think, that Dr. May- 

 cock did not even know yet the existence of that new instru- 

 ment, the electric column j or at least had not had the oppor- 

 tunity of seeing any j for each column, of whatever number of 

 groups it is composed, which constantly remain in contact, pro- 

 duces electrical effects at its extren^ities, in proportion to the 

 number of groups. 

 This oqnally Q. Dr. Maycock, not having read my papers, might say, that 

 * p .ice jjghad applied his system only to the golvanic pile 3 but had he 



kuowa 



