of the Induction Current. 5 



for the inducing induction current produces in it a current of 

 the same direction as the opposite current which reacts upon this. 

 But I had no coil of a sufficient number of windings, which I 

 might have inserted in the accessory coil, so as in this way com- 

 pletely to destroy the opposite current. 



The inductorium itself gives the second proof of the existence 

 of the supposed opposite current. For to produce the often 

 mentioned phenomena of tension it is unnecessary to use an 

 accessory coil ; the inductorium itself is quite sufficient. 



Nothing more is necessary than that, after the poles of the 

 instrument at work have been united with one another by a 

 short wire, the inducing coil together with its iron core be par- 

 tially withdrawn. On commencing, free electricity appears in 

 the junction wire, and it increases until about two-thirds or 

 three-fourths of the coil are withdrawn from the induction coil. 

 It is true that in this case the empty part of the induction coil 

 represents the position of the accessory coils in the earlier expe- 

 riments, and so far this result is not surprising. 



If now the inducing coil is slowly reinserted, free electricity 

 begins to decrease, and continues to entire disappearance when the 

 coil has been restored to its original position. This also is 

 natural. 



But, it may be asked, what happens in this second process ? 

 Obviously nothing else than that, in the coils of the empty part 

 of the induction coil, the original induction, partly or entirely 

 removed, is reproduced. This induction destroys the earlier 

 condition. But what destroys an induction can be only an in- 

 duction, and one of opposite direction ; hence by this experi- 

 ment the existence of the opposite current is proved. I do not 

 suppose that anything well founded can be urged against these 

 simple conclusions. 



1 will only add that the phenomenon of tension in question, 

 if purely one of resistance, could never entirely disappear, but 

 rather, even with the very best conduction between the poles of 

 the instrument, must occur in full force ; for each partial current 

 which is induced in an individual spire of the induction coil has 

 to traverse the sum of all the other spires of the coil, and hence 

 to overcome a resistance which would be quite sufficient to cause 

 free electricity to appear if this were merely evoked by resistance. 



From all this I consider the origin of free electricity in the 

 circuit of a metallic closed inductorium to be sufficiently esta- 

 blished, and hence I think myself justified in passing over other 

 experiments which I have undertaken in this direction. 



Yet I cannot help discussing an objection which seems to 

 follow from the statement that the striking-distance of the in- 

 duction spark undergoes no enfecblement from a wire circuit 



