INDUCED ELECTRICITY. 



31 



shown. This increase of the power of the current of the first helix 

 would have increased in proportion, by its influence, the power of 

 the current of the second helix. This is all. To say that the 

 magnet acts directly upon the second helix, and confers special 

 properties upon its current, is mere hypothesis, and the objection 

 is set aside by my experiments. 



We may therefore say that the special action of the current of 

 the second helix upon the cutaneous sensibility, or the special 

 action of a helix of fine and long wire induced by a helix of wire 

 that is thicker and shorter, cannot be explained entirely by the 

 great tension of the current. What, then, is the exact explanation 

 of the phenomenon? This is a question that ought to employ 

 the ingenuity of the learned physicists who have criticised my re- 

 searches ; and who, I repeat, by reason of their special knowledge 

 are far more competent than myself to enter upon such inquiries. 



Let us, however, admit for an instant that the greater action of 

 the current of the second helix upon cutaneous sensibility is due 

 solely to the greater tension of this current. How, then, shall we 

 explain why the current of the first helix, the tension of which is 

 infinitely less, excites much more acutely than the other the sensi- 

 bilities of certain sub-cutaneous organs (muscles, nerves, bladder, 

 rectum, testes) ? How, also, shall we explain the elective action 

 of the current of the second helix upon the sensibility of the 

 retina ? ^ 



^ M. Chauveau, endeavourinpf in a 

 recent boolc to generalize on the pliysio- 

 logical effects of induced currents, has 

 concluded from some experiments on 

 animiik : — " 1. That the physiological 

 effect of electricity is the result of a 

 mechanical disturbance of the molecules 

 in the track of the currents. 2. That 

 this disturbance depends entirely upon 

 the tension of the currents, and is not 

 directly influenced by the quantity of 

 electricity set in motion. 3. That the 

 various portions of the track of the elec- 

 tricity, in an animal conductor, do not 

 undergo the same degree of mechanical 

 excitation ; because the tension, instead 

 of being uniform throughout the con- 

 ductor, is always stronger at the extreme 

 points, and, especially, at the point of 

 escape (negative pole).'' 



The experiments made upon the human 

 subject, Ity the aid of localized electricity, 

 and described in the text, show that the 

 energy of all the physiological effects of 

 an induced current, far from being always 

 in direct proportion to its tension, is 

 sometimes greater under the influence of 

 a current of lower tension (the current 



of the first helix, or the extra current of 

 authors). 



I should observe also, that it is known 

 in physics, and may be shown by experi- 

 ment, contrary to the statement of M. 

 Chauveau, that the electric current lias 

 less tension at the negative than at the 

 positive pole ; so that a more powerful 

 physiological action at the negative pole 

 cannot be attributed to the greater tension. 



Lastly, M. le vicomte Dutuoncel gave 

 additional support to the position that I 

 defend, in a work that he addressed in 

 1859, to the Academy of Sciences. He 

 has shown by experiment that the physio- 

 logical power of an induced current is 

 not always due io its tension ; and his 

 experiment is described in the following 

 communication, witli which this inge- 

 nious and learned physicist has favoured 

 me. 



" We may," he says, " conclude from 

 this experiment, that the tension is not 

 the sole cause of the power of induced 

 currents to produce physiological effects ; 

 and that the different effects observed 

 by M. Duchenne, from the action of 

 secondary currents and extra currents, 



