The Electric Current around the Gymnotus. 365 



1772. As, at the moment when the fish wills the shock, the 

 anterior parts are positive and the posterior parts negative, 

 it may be concluded that there is a current from the former 

 to the latter through every part of the water which surrounds 

 the animal, to a considerable distance from its body. The 

 shock which is felt, therefore, when the hands are in the most 

 favourable position, is the effect of a very small portion only 

 of the electricity which the animal discharges at the moment, 

 by far the largest portion passing through the surrounding 

 water. This enormous external current must be accom- 

 panied by some effect within the fish equivalent to a cur- 

 rent, the direction of which is from the tail towards the head, 

 and equal to the sum of all these external forces. Whether 

 the process of evolving or exciting the electricity within the 

 fish includes the production of this internal current (which 

 need not of necessity be as quick and momentary as the ex- 

 ternal one), we cannot at present say; but at the time of the 

 shock the animal does not apparently feel the electric sensa- 

 tion which he causes in those around him. 



1773. By the help of the accompanying diagram I will 

 state a ^o.^ experimental results which illustrate the current 

 around the fish, and show the cause of the difference in cha- 

 racter of the shock occasioned by the various ways in which 

 the person is connected with the animal, or his position al- 

 tered with respect to it. The large circle represents the tub in 

 which the animal is confined ; its diameter is forty-six inches, 

 and the depth of water in it three inches and a half; it is 

 supported on dry wooden legs. The figures represent the 

 places where the hands or the disc conductors (1757.) were 

 applied, and where they are close to the figure of the animal, 

 it implies that contact with the fish was made. I will desig- 

 nate different persons by A, B, C, &c., A being the person 

 who excited the fish to action. 



1774'. When one hand was in the water the shock was felt 

 in that hand only, whatever part of the fish it was applied to ; 

 it was not very strong, and was only in the part immersed in 

 the water. When the hand and part of the arm was in, the 

 shock was felt in all the parts immersed. 



1775. When hoth hands were in the water at the 5«wepart 

 of the fish, still the shock was comparatively weak, and only 

 in the parts immersed. If the hands were on opposite sides, 

 as at 1, 2, or at 3, 4, or 5, 6, or if one was above and the 

 other below at the same part, the effect was the same. When 

 the disc collectors were used in these positions no effect was 

 felt by the person holding them, (and this corresponds with 

 the observation of Gay-Lussac on Torpedos*,) whilst other 



* Annales de Chimie, xiy. p. 18. 



