278 LOCALIZED ELECTRIZATION. 



have ascertained that when, by suppressing the solution of con- 

 tact of the thick wire, and leaving its circuit interrupted, there 

 remained only the direct influence of the magnet upon the second 

 wire, the physiological effects produced by this influence are 

 reduced almost to nothing. 



To sum up. In my double-current electro-magnetic apparatus, it 

 is the current developed in the primary coil, under the simul- 

 taneous influence of the temporary modifications of the magnet, 

 and of tlie interruptions produced in the circuit of the thick wire, 

 which reacts upon the secondary coil. 



Although, until quite recently, the above proposition was con- 

 sidered inadmissible by eminent physicists, I do not the less 

 maintain my belief that it rests upon fact and experiments that 

 are incontestable. It has been demonstrated, in a more scientific 

 manner, and in more technical language, by M. F. P. Le Roux, 

 who, in his thesis presented to the upper school of pharmacy, 

 which 1 have already had occasion to quote, has maintained that 

 my idea is in great part correct, at least in the case of my magneto- 

 faradic apparatus. 



The following is an extract from the thesis, remarkable in 

 many other respects, in which this impoi'tant demonstration is 

 to be found. (The reader will easily understand this demon- 

 stration, if he is acquainted with the theory of magneto-electric 

 instruments which M. Le Iloux has laid down in his work, with 

 reference to the apparatus of Pixii, and which I have reprinted 

 on page 287) : — 



" M. Duchenne has attributed the particular effects which he 

 has observed in his second coil, to the action of currents, the 

 distribution and intensity of which are different from those of 

 the currents which are induced in the primary coil. Others, 

 on the contrary, have thought that the two coils differ only in 

 the length of their wires. I am induced to believe that Mhat is 

 wanting to the idea of M. Duchenne is to be supported hy precise 

 reasoning, and that it is in the main correct, at least in the case of 

 his magneto-faradic apparatiis. 



"It may be regarded as proved that, in all magneto-electric 

 instruments of small dimensions, the alternations of magnetization 

 and demagnetization are insuflScient to produce currents capable 

 of causing shocks, whatever be the speed of the armatures or the 

 reels, or whatever the length of the wires ; while the interruption 

 of the current, near the time of its maximum intensity, causes them 

 energetically. The reason of this is, that the diminution of inten- 

 sity which takes place at the moment of an interruption is much 

 more rapid than the most rapid demagnetization that can be pro- 



