30 VHILOSOPHICAL TRANSACTIONS. [aNNO 1776. 



shock in both of them, I accordingly tried the same experiment with the arti- 

 ficial torpedo ; and if the battery was charged about 6 times as high as usual, re- 

 ceived a small shock in each hand.* No sensible difference could be perceived in 

 the strength, whether the torpedo was inclosed in the basket or not. The trough 

 in which this experiment was tried was 36 inches long, 14-i- broad, and l6 deep ; 

 and the distance of that hand which was immersed in the water from the elec- 

 tric organs of the torpedo, was about 14 inches. As it was found necessary to 

 charge the battery so much higher than usual, in order to receive a shock, it 

 follows, that unless the fish with which Mr. Walsh tried this experiment was 

 remarkably vigorous, there is still too great a disproportion between the strength 

 of the shock of the artificial torpedo when received under water and out of it. 

 If this is the case, the fault might evidently be remedied by making it of some 

 substance which conducts electricity better than leather. 



When the torpedo happens to be left on shore by the retreat of the tide, it 

 loosens the sands by flapping its fins, till its whole body, except the spiracles is 

 buried ; and it is said to happen sometimes, that a person accidentally treading 

 on it in that situation, with naked feet, is thrown down by it. I therefore filled 

 a box, 32 inches long and 22 broad, with sand, thoroughly soaked with salt 

 water, to the depth of 4 inches, and placed the torpedo in it, entirely covered 

 with the sand, except the upper part of its convex surface, and laid one hand on 

 its electrical organs, and the other on the wet sand about l6 inches from it. I 

 felt a shock, but rather weak ; and about as strong as if the battery had been 

 charged half as high, and the shock received in the usual way. 



I next took 2 thick pieces of that sort of leather which is used for the soles of 

 shoes, about the size of the palm of my hand ; and having previously prepared 

 them by steeping in salt water for a week, and then pressing out as mucii of the 

 water as would drain off easily, repeated the experiment with these leathers 

 placed under my hands. The shock was weaker than before, and about as strong 

 as if received in the usual way with the battery charged one third part as high. 

 As it would have been troublesome to have trod on the torpedo and sand, I chose 

 this way of trying the experiment. The pieces of leather were intended to re- 

 present shoes, and in all probability the shoes of persons who walk much on the 

 wet sand will conduct electricity as well as these leathers, I think it likely, 

 therefore, that a person treacling in this manner on a torpedo, even with shoes 

 on, but more so without, may be thrown down, without any extraordinary 

 exertion of the animal's force, considering how much the efl^ect of the shock 

 would be aided by the surprize. 



* As well as I could judgu, die battery required to be charged about 1 6 or 20 times as high, to 

 give a shock of the same strength -when recci\ ed this way as w hen received in the usual manner \\ ith 

 the torpedo out of water. — Orig. 



