297 



ever. The explanation of this fact was given by supposing that in 

 the inducted spiral, either electricity does not circulate in the minutest 

 degree or that two equal opposing currents produce no effect on the 

 human organism; reasoning by analogy from what occurs when the 

 magnetic needle, which, subjected to two equal and opposite currents, 

 remains in a state of perfect equilibrium. The individual endowed 

 with special nervo-muscular sensibility had a distinct sensation at the 

 wristband metacarpal portions of both hands. The experiment was 

 repeated in order that we might be assured of its accuracy. 



What probable explanation can we give of this phenomenon? It 

 appears to me that we are authorized to say, that two currents, taking 

 opposite directions, do not neutralize each other, just as in acoustics 

 the reflected wave is not destroyed by the direct one; but still the ex- 

 periencing of such a sensation supposes an organism of unusual deli- 

 cacy. We may, indeed, sa}-^ that there are electrical currents, by 

 indtiction, at the beginning and at the termination of the discharge 

 from the Leyden jar. Could these two actions, which must be sepa- 

 rated from each other by a very minute fraction of time, be the cause 

 of the abovementioned special sensation? The interval which sepa- 

 rates the opposite currents would be .0003 of a second, on the suppo- 

 sition that the medium velocity of the electric fluid is 100 metres in a 

 second. 



1 have felt gratified in comparing the electric nervo-muscular sensi- 

 bility with the mechanical power of the individuals subjected to the 

 preceding experiments. I have not found any assignable proportions, 

 either in a direct or inverse sense, between the two. The person 

 who felt the inducted current at the distance of 0.30, displayed by 

 the dynamometer of Renier a muscular power of the hand equal to 

 82 kilogrammes; and the one who felt the inducted current at the dis- 

 tance of 0.07 centimetres, exhibited, by the dynamometer, a power 

 equal to 92 kilogrammes. 



I will exhibit, at a glance, the series of these experiments, and indi- 

 cate some, at least, of the names of the young men who have been 

 subjected to them. 



Other individuals who had submitted to the experiments on the 



VOL. VI. — 2 T 



