Induction of instantaneous Electric Currents. 505 



Leyden jar upon the actuating wire under the most favour- 

 able circumstances for obtaining the induced current; but the 

 galvanometer did not make the smallest movement ; nor was 

 the result different when experimenting with the bands of lead 

 instead of the copper wires ; and this proves that such ac- 

 tuated currents are instantaneous, like the actuating. 



XVII. On obliging the actuating current to pass through 

 a metallic wire several hundred meters in length, the induced 

 current was excited ; nor did I perceive any different effect 

 when it did not pass through that long wire. The same re- 

 sult also occurred when I forced the induced current to pass 

 through the long wire before reaching the re-electrometer. 



The induction did not fail either, when, instead of one end 

 of the actuated wire being in metallic contact with one end 

 of the coil of the re-electrometer, both were immersed in 

 water, and distant from each other more than a decimeter ; 

 nor was the result different when the actuating current was 

 made to pass through a stratum of water more or less thick. 



The inductions of the second and third orders also, did 

 not fail when made to pass through a long metallic wire or a 

 stratum of water, although under such circumstances they 

 appeared much weaker. 



XVIII. Making use of a small iron cylinder surrounded 

 by two parallel coils, similar to that mentioned in § I., I con- 

 nected the two ends of one of them, and having discharged 

 upon the other the small Leyden jar charged to fifteen de- 

 grees, no movement of the magnetized needle ensued ; and the 

 reason appears to me to be that the current induced in the 

 circuit so formed was contrary, and nearly equal in magneti- 

 zing force to the immediate current. 



I have also constantly observed, that the somewhat weaker 

 currents of the first two or three residual charges were 

 indicated by one or two degrees of deviation ; and this, as 

 it appears to me, arises from the weakest current not being 

 sufficient to cause a sensible induced current in the wire 

 circuit already mentioned. 



Thus I have seen that a stronger charge, for example of 

 forty or fifty degrees, was indicated by several degrees of de- 

 viation ; never, however, so many as were observed when the 

 other wire was unconnected : and this shows that when the 

 wire was joined the immediate current prevailed over the in- 

 duced. 



XIX. The phenomena of induction of which I have hitherto 

 spoken, presented no anomalies to me ; but this was not the 

 case with respect to the direction of the induced current. In 

 most of the experiments on this subject I made use of three 



