On Electro- Dynamic Induction. 225 



tion, can neutralize each other ? I was at first disposed to con- 

 sider the phenomenon as a case of real electrical interference, in 

 which the impulses succeed each other by some regular interval. 

 But if this were true, the effect should depend on the length and 

 other conditions of the current in the interposed conductor. In 

 order to investigate this, several modifications of the experiments 

 W€re instituted. 



68. First a flat coil (No. 3) was interposed instead of the plates. 

 When the two ends of this were separated, the shocks were re- 

 ceived as if the coil were not present ; but when the ends were 

 joined, so as to form a perfect metallic circuit, no shocks could be 

 obtained. The neutralization with the coil in this experiment 

 was even more perfect than with the plate. 



69. Again, coil No. 2, in the form of a ring, was placed not 

 between the conductors, but around the helix. With this dispo- 

 sition of the apparatus, and the ends of the coil joined, the shocks 

 were scarcely perceptible, but when the ends were separated, the 

 presence of the coil has no effect. 



70. Also when helices No. 1 and 2 were together submitted to 

 the influence of coil No. 1, the ends of the one being joined, the 

 other gave no shock. 



71. The experiments were further varied by placing helix No. 

 2 within a hollow cylinder of sheet brass, and this again within 

 coil No. 2, in a manner similar to that shown in Fig. 12, which is 

 intended to illustrate another experiment. In this arrangement 

 the neutralizing action was exhibited, as in the case of the plate. 



72. A hollow cylinder of iron was next substituted for the one 

 of brass, and with this also no shocks could be obtained. 



73. From these experiments it is evident that the neutraliza- 

 tion takes place with currents in the interposed or adjoining con- 

 ductors of all lengths and intensities, and therefore cannot, as it 

 appears to me, be referred to the interference of two systems of 

 vibrations. 



74. This part of the investigation was, for a time, given up 

 almost in despair, and it was not until new light had been ob- 

 tained from another part of the inquiry, that any further advances 

 could be made towards a solution of the mystery. 



75. Before proceeding to the next Section, I may here state, 

 that the phenomenon mentioned, paragraph 54, in reference to 

 helix No. 4, is connected with the neutralizing action. The 



Vol. XXXVIII, No. 2.— Jan .-March, 1840. 29 



