Jb gbnoJdLXXVII. Second Memoir on Induction,' oAi lo liuq 

 By Prof. Elie WAiiTMANW*inaj ai s'lJnao orfj 



' 9 vit. 0?i ^^f- Non-interference of Electric Currents. 

 58. A MONG the theories of electricity, those of statical 



<, and dynamical induction appear to be of the g,veg\io 



est importance. It may even be said that the explanation ^ 

 of the phaenomena of induction would serve to establish th^i 

 true theory of electricity. On the other hand, some exp^rij 

 rimental data on the properties by which this fluid is allied 

 to, or distinguished from, caloric and light, would be very 

 useful for a clear comprehension of that action of influence, 

 which seems to belong to it peculiarly. I propose, in the pr^rja 

 sent memoir, to examine whether dynamical electricity can 

 cause interferences analogous to those which the two other 

 imponderable agents present. , .,t ji 



59. Are two electrical currents issuing from similar or the 

 same sources, and primitively equal, capable of neutralizing 

 each other wholly or in part, when, one of them preserving a 

 constant intensity, that of the other varies until it becomes 

 almost evanescent compared with the first ? This is the pro- 

 blem which I have sought to solve by three independent me- 

 thods, that of induced currents, that of direct and continuous 

 currents, and that of derivations. The necessity of measu- 

 ring with great accuracy the conductors which the currents 

 traverse, and the absolute ignorance we are in as to the lengths 

 of the electric undulations (if indeed electricity is a phaeno- 

 menon in which the movements of the aether have a share), 

 render the experiments which I proceed to describe very de- 

 licate and tedious. They have all been repeated a great 

 number of times : the principal ones have been laid before tha 

 Soci^te des Sciences de Lausanne. ^^ r.oiTaupo oHj 



usfetJnao D^A. Method of Induced Currents.\^o^i^i eirfj^lqqe 



60. In my first memoir I showed (22) that on passing di- 

 rect currents of the same direction by two inductor wires, a 

 current was induced equal to the sum of their elementary ef- 

 fects, whilst (23, 24), if the two inducing currents are perfectly 

 equal and in contrary directions, the two induced currents 

 neutralize one another, or, rather, have no sensible existence. 

 But on lengthening one of the inductor wires and leaving the 

 other constant, the equality of their conductibility and of 

 their inductive power ceases ; then the needle of the rheome- 



* Read March 19, 1845, before the Societe Vaudoise des Sciences Na- 

 turelles. The first memoir was inserted in the Philosophical Magazine, 

 vol. XXV. p. 266, and in the Archives de V Electricite, vol, iv. p. 34, 



