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appreciable by a young man 20 years old. Nor have I even found 

 the nervo-muscular sensibility to be in inverse proportion to the dy- 

 namic force, as measured by a dynamometer. It follows, that there 

 is a^ quite peculiar and special ratio for which we can assign no 

 reason, and we are constrained to say there is none to be found. 

 The ascertained limits, among twelve persons, were from a distance 

 of 0.04 metres to that of 0.30 metres, between the inducting and 

 the inducted spirals. These extremes will give the proportion of 

 nervo-muscular sensibility of 1 : 56,25 calculated according to the law 

 of the inverse ratio of the squares of the distance. An electric tension, 

 therefore, 56,25 times greater in one would produce an equal degree of 

 tension as a simple unit in another; which is equivalent to saying that 

 the electric nervo-muscular sensibility in one individual was 56,25 

 times greater than in another. This individual at the distance of 25 

 centimetres of the inducted from the inducting spiral, experienced 

 such a distressing sensation that he could not bear the electric shock. 

 At the same distance, all the other individuals experienced no sensible 

 effects whatever: and with this, which might be termed the most at- 

 tenuated action, the effect on the organism was such that it gave rise 

 to pains in the bowels and copious evacuations as if a purgative had 

 been taken. In other respects the activity of the digestive function 

 was not increased, as is the case in some individuals. We learn 

 from all this what circumspection and caution ought to be exercised 

 in the application of electricity to the human frame. I must here 

 record a phenomenon of quite a special character, which was exhibited 

 in the individual who was endowed with such rare electric nervo-mus- 

 cular sensibility, on account of the interest which it excites towards 

 the explanation of a result that has given rise to grave discussions, 

 both in Italy and in other countries. I refer to the simultaneous 

 passage of two or more opposite electrical currents through the same 

 wire. The apparatus which I made use of was my differential dy- 

 namic inductionmeler, which is made of three plane spirals. It is well 

 ascertained that when the electric current travels along, in the same 

 direction, two inducting spirals, there is an electrical current in the in- 

 ducted spiral which is comprised in and restricted to the space inter- 

 posed between the two inducting spirals — an effect by induction which 

 is greater in proportion to the increased tension of the Leyden electrical 

 discharge, and diminished distance between the inducting and the in- 

 ducted spiral. It is equally well known that when the electric cur- 

 rent is sent in opposite directions along two inducting spirals, and that 

 these latter are precisely equidistant from the inducted spiral, the per- 

 son who completes the circle by this spiral experiences no effect what- 



