TRANSACTIONS OF THK SECTIONS. 21 



Although these results may seem at first anomalous, yet they are 

 still such as would necessarily arise out of the known operation of 

 electrical induction. The inductive process is not confined to the 

 case of a charged and neuti'al body, but operates more or less freely 

 even between bodies similarly charged : whatever therefore be the 

 precise nature of the inductive force, it is present in every case of 

 statical electrical action, although under certain conditions the re- 

 sulting attraction attendant on it is not always apparent, or is 

 otherwise of a negative character ; the tendency of the inductive 

 action being first, to raise the anti-attractive state of the bodies to 

 zero, if sucli previously exist ; secondly, to generate in them an 

 actual atti"active force. He conceives, therefore, that no essential 

 difference exists in this process, whether it take place between si- 

 milarly or dissimilarly charged bodies, or between a charged and a 

 neutral body. The only distinction necessaiy is, that in the latter 

 case the induction commences at a limit which may be termed zero ; 

 in the former cases it commences either above or under that limit. 

 The author considers that electrical induction between two similarly 

 charged bodies, may become indefinitely modified by the various 

 circumstances of quantity, intensity, distance of the repelling bodies, 

 and the like, giving rise to apparently complicated phenomena, as 

 he thinks is evident in his tabulated results. One condition favour- 

 able to the disturbances above mentioned, and of importance to 

 notice, is the inequality of the repelling bodies in respect of ex- 

 tension. Thus in connecting an insulated sphere with the fixed ball 

 of the balance, the force between the discs will be often in the simple 

 inverse ratio of the distance, or at least very nearly in that ratio, and 

 will be frequently in the ratio of 3:1, when the quantity of elec- 

 tricity on the charged sphere is as 2 : 1 . 



The author considers these facts of great consequence to any ex- 

 perimental inquiry in electricity through the agency of repulsion, 

 more especially those connected with the use of the proof plane. 

 The relative electrical capacities of a hoUow sphere and a circular 

 plate of equal area, each side to each side, as determined by Cou- 

 lombe's method, is involved in some uncertainty on this account. 

 In the detail of Coulombe's experiments, given in Biot's celebrated 

 Traite de Physique, the capacities of the plane and sphere appear to 

 be in the ratio of 2 : 1 . Hence the plane is considered to have a 

 double surface of action, the interior surface of the sphere not par- 

 ticipating in the distribution of the charge. The result of the con- 

 tact however of the plane and sphere, and from which it is inferred 

 that the electricity became finally shared between them, in proportion 

 to their exterior surfaces, does not seem to have been compared with 

 the result of a similar contact between the charged sphere and a 

 neutral sphere of the same diameter. According to the theory, the 

 electrical reactions after contact with the plate should greatly ex- 

 ceed that after contact with a similar sphere ; it should in fact be 

 the same as that after contact with a sphere whose exterior surface 

 was equal to the two surfaces of the plate. This point deserve* 



