of the Induction Current. 3 



closing, as an extra current, I do not hesitate to designate the 

 current in question as the extra current of the induction current. 



To test this view more accurately, it appeared best to inves- 

 tigate the deportment of various induction apparatus to each 

 other. 



I first combined two apparatus of this kind, as similar as pos- 

 sible, in opposite directions, by joining in a corresponding manner 

 the two external divisions of an inductorium with three divisions, 

 by bright copper wires of small length. Although each of these 

 divisions only contained 1200 feet of copper wire of 0*25 millim. 

 in thickness, and, both united in the same direction, exhibited no 

 perceptible trace of tension, yet when united in opposite direc- 

 tions their junction wires gave painful sparks. 



There was no current in this; for an electrical egg interposed 

 in one of the joining wires showed no luminous phenomena. 



Thereupon I combined this inductorium as a whole, in which 

 it contained about 3800 feet of wire, in an opposite direction 

 with another large apparatus whose induction coil consisted of 

 23,000 feet of wire fth of a millim. in thickness, in which I 

 passed one and the same voltaic current through the inducing 

 coils of both, and interrupted them by one and the same hammer. 



I began by testing the induction coils singly, by causing 

 one to give sparks at the micrometer while the other was closed 

 by metal. As was to be presupposed, the larger apparatus was 

 the more powerful; the striking-distance of its sparks was more 

 than double that of the sparks of the smaller. 



When they were now combined in an opposite direction (that 

 is, the similar poles of both coils united) by bright copper wires 

 of no great length, a current moved in the direction of the 

 stronger apparatus accompanied by a tension upon the joining 

 wires, which yielded even more piercing sparks than those in the 

 former case*. 



Both these results serve doubtless as a support of my view, in 

 so far as they show that when, in a closed circuit of wire, two 

 induction currents (whether equally or unequally strong is quite 

 immaterial) act in opposite directions to each other, free elec- 

 tricity occurs. 



It was now necessary to furnish a proof that in the original 

 experiment the current of the inductorium evoked an opposite 

 current (Gegenstrom) in the accessory wire. This was effected in 

 two ways. 



* I will not omit to mention that even when both apparatus were joined 

 in the same direction, a tension was indeed observed on the wires, though 

 somewhat feeble. This, however, I can only consider as abnormal, arising 

 from some not yet explained circumstance. For, if it were normal, it must 

 occur in each individual inductorium, as that may always be supposed to 

 consist of two unequal instruments acting in the same direction. 



B2 



