INDUCED ELECTRICITY. 19 



every completion and interruption of the current, but in opposite JLP 

 directions for the two. y 



The current that is instantaneously developed in the second coil, 

 at the moment when the circuit formed by the first coil and the 

 battery is completed, pursues an opposite direction to that of 

 the current of the battery. It is, doubtless, for this reason that it 

 has been termed the negative or inverse induced current. On the 

 contrary, the current induced in the second coil, at the moment 

 when the circuit of the first coil is interrupted, travels in the same 

 direction as that of the generator current, and is called the positive 

 or direct induced current. Lastly, it may be shown that the 

 tension of the induced is infinitely greater than that of the extra 

 current. It therefore follows that the identity of the two currents 

 is not" perfect; and I shall hereafter show, experimentally and by 

 clinical observation, that the two currents differ essentially as 

 regards their physiological action. 



I have stated that the circuit developed in the first wire has 

 been called by authors the extra or inductive current ; and that 

 of the second or superimposed wire the induced current of the 

 first kind. I myself formerly called them the current of the first 

 and of the second kind. 1 now discard these appellations, in 

 order not to introduce confusion into scientific nomenclature, and 

 because the new terms that I propose are most in accordance 

 with reason and physiology. For the future I shall not employ 

 the expressions formerly used to denote the different currents, 

 because these expressions are liable to be misinterpreted by the 

 generality of practitioners, who are not familiar with the history 

 of the ancient nomenclature. 1 shall speak of the extra current as 

 the current of the first coil ; and of the current of the first kind, of 

 authors, as the current of the second coil. I hope that these 

 names, perfectly intelligible to everybody and not oj)posed to any 

 hypothesis, will be generally accepted by the profession.^ 



^ The experimental researches that 1 i felt, however, that I was justified in an 

 published some years ago, and of whicli | endeavour to express in the clearest 

 I may say that their exactness has never i manner the current with which we are 

 been dispuled, although the facts have \ now concerned. Perhaps I ought to ex- 

 been variously interpreted, have bhown \ plain on what the general nomenclature 

 in an incontestable manner that the two j of induced currents is founded, 

 induction currents possess each their That has happened with regard to the 

 special qualities, depending not only upon currents of induced electricity, whicli 



tlie length and thickness of the wire, 

 but also upon the mode of induction. 

 It was therefore necesi^ary to denote the 

 two currents by terms perfectly clear and 

 precise; for which purpose it was neces- 

 sary to modify the existing nomenclature : 

 a proceeding that should never be at 



commonly happens with regard to many 

 other matters ; the nomenclatuie of the 

 subject has been built up gradually, in 

 accordance with the growth of science. 

 The first discovery of Faradny was simply 

 that a fine metallic thread, rolled around 

 another thread that was traversed by a 



tempted without absolute necessity. I current, became itself the seat of an 



