g'a. PHILOSOPHICAL TRANSACTIONS. [aNNO 1776. 



not pass, unless the knobs were brought so near together as to require the assist- 

 ance of a magnifying glass to be sure that they did not touch. 



I took a chain of small brass wire, and holding it in one hand, let the lowest 

 link lie on the upper surface of an electric organ, while my other hand was ap- 

 plied to the opposite surface. The event was, that if the link held in my hand, 

 was the 5th or 6th from the bottom, and consequently that the electricity had 

 only 4 or 5 links to pass through besides that in my hand, I received a shock ; 

 so that the electricity was able to force its way through 4 or 5 intervals of the 

 links, but not more. If, instead of this chain, I used one composed of thicker 

 wire, the shock would pass through a great number of links ; but I did not 

 count how many. It must be observed, that the principal resistance to the pas- 

 sage of the electrical fluid is formed by the intervals of the lower links of the 

 chain ; for as the upper are stretched by a greater weight, and therefore pressed 

 closer together, they make less resistance. Consequently the force required to 

 make the shock pass through any number of intervals, is not twice as great as 

 would be necessary to make it pass through half the number. For the same 

 reason it passes easier through a chain consisting of heavy links than of light 

 ones. Whenever the electricity passed through the chain, a small light was 

 visible, provided the room was quite dark. This however affords no argument 

 for supposing tliat the phenomena of the torpedo are not owing to electricity ; 

 for its shock has never been known to pass through a chain or any other inter- 

 ruption in the circuit ; and consequently it is impossible that any light should 

 have been seen. 



In all these experiments, the battery was charged to the same degree; namely, 

 such that the shock was nearly of the same strength as that of the leathern tor- 

 pedo, and which I am inclined to think, from my conversation with Mr. Walsh, 

 may be considered as about the medium strength of those of a real one of the 

 same size as this. 



As it appeared, that a shock of this strength would {)ass through a few inter- 

 vals of the links of the chain, I tried what a smaller would do. If the battery 

 was charged only to a 4th or 5th part of its usual height, the shock would not 

 pass through a single interval : but then it was very weak, even when received 

 through a piece of brass wire, without any link in it. This chain was quite 

 clean and very little tarnished ; the lowest link was larger than the rest, and 

 weighed about 8 grains. If I used a chain of the same kind, the wire of which, 

 though pretty clean, was got brown by being exposed to the air, the shock 

 would not pass through a single interval, with the battery charged to about one- 

 third or one-half its usual strength. 



It appears, that in this respect the artificial torpedo does not completely imi- 



