INDUCTIVE ACTION OF AN ELECTRIC CURRENT. 55 



1112. Another bundle, containing twenty of these wires, was eighteen feet long: 

 the terminal pieces were one fifth of an inch in diameter, and each six inches long. 

 This was compared with nineteen feet in length of copper wire one fifth of an inch in 

 diameter. The bundle gave a smaller spark on breaking contact than the latter, even 

 when its strands were held together by string : when they were separated, it gave a 

 still smaller spark. Upon the whole, however, the diminution of effect was not such 

 as I expected ; and I doubt whether the results can be considered as any proof of 

 the truth of the supposition which gave rise to them. 



1113. The inductive force by which two elements of one current (1109. 1110.) act 

 upon each other, appears to diminish as the line joining them becomes oblique to the 

 direction of the current, and to vanish entirely when it is parallel. I am led by some 

 results to suspect that it then even passes into the repulsive force noticed by Ampere*; 

 which is the cause of the elevations in mercury described by Sir Humphry Davy -f, 

 and which again is probably directly connected with the quality of intensity. 



1114. Notwithstanding that the effects appear only at the making and breaking of 

 contact, (the current remaining unaffected, seemingly, in the interval,) I cannot resist 

 the impression that there is some connected and correspondent effect produced by 

 this lateral action of the elements of the electric stream during the time of its conti- 

 nuance (60. 242.). An action of this kind, in fact, is evident in the magnetic relations 

 of the parts of the current. But admitting (as we may do for the moment) the mag- 

 netic forces to constitute the power which produces such striking and different results 

 at the commencement and termination of a current, still there appears to be a link in 

 the chain of effects, a wheel in the physical mechanism of the action, as yet unrecog- 

 nised. If we endeavour to consider electricity and magnetism as the results of two 

 forces of a physical agent, or a peculiar condition of matter, exerted in determinate 

 directions perpendicular to each other, then, it appears to me, that we must consider 

 these two states or forces as convertible into each other in a greater or smaller degree ; 

 i. e. that an element of an electric current has not a determinate electric force and a 

 determinate magnetic force constantly existing in the same ratio, but that the two 

 forces are, to a certain degree, convertible by a process or change of condition at pre- 

 sent unknown to us. How else can a current of a given intensity and quantity be 

 able, by its direct action, to sustain a state which, when allowed to react, (at the ces- 

 sation of the original current,) shall produce a second current, having an intensity 

 and quantity far greater than the generating one ? This cannot result from a direct 

 reaction of the electric force ; and if it result from a change of electrical into mag- 

 netic force, and a reconversion back again, it will show that they differ in some- 

 thing more than mere direction, as regards that agent in the conducting wire which 

 constitutes their immediate cause. 



1115. With reference to the appearance, at different tunes, of the contrary effects 



* Recueil d' Observations Electro-Dynamiques, p. 285. 

 t Philosophical Transactions, 1823, p. 155. 



