2o6 Memoir on the Torpedo as imitated by electricity 



stance of the shock's not being able to pass through any sensible space 

 of air. In all my experiments on this head, I used the first torpedo, or that 

 made of wood ; for as it is not necessary to charge the battery more than 

 one-third part as high to give the same shock with this as with the other, 

 the experiments were more likely to succeed, and the conclusions to be 

 drawn from them would be scarcely less convincing: for I find, that five 

 or six rows of my battery will give as great a shock with the leathern 

 torpedo, as one row electrified to the same degree will with the wooden 

 one ; consequently, if with the wooden torpedo and my whole battery, I 

 can give a shock of a sufficient strength, which yet will not pass through 

 a chain of a given number of links, there can be no doubt, but that, if 

 my battery was five or six times as large, I should be able to do the same 

 thing with the leathern torpedo. 



426] I covered a piece of sealing wax on one side with a slip of tinfoil, 

 and holding it in one hand, touched an electrical organ of the torpedo 

 with the end of it, while my other hand was applied to the opposite surface 

 of the same organ. The shock passed freely, being conducted by the 

 tinfoil; but if I made, with a penknife, as small a separation in the tinfoil 

 as possible, so as to be sure that it was actually separated, the shock would 

 not pass, conformably to what Mr Walsh observed of the torpedo. 



427] I tried the experiment in the same manner with the Lane's 

 electrometer described in Art. 405, and found that the shock would not 

 pass, unless the knobs were brought so near together as to require the 

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



428] 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 applied to the opposite surface. The event was, that if the link, 

 held in my hand, was the fifth or sixth from the bottom, and consequently, 

 that the electricity had only four or five links to pass through besides 

 that in my hand, I received a shock; so that the electricity was able to 

 force its way through four or five intervals of the links, but not more. One 

 gentleman, indeed, found it not to pass through a single interval; but in 

 all probability the link which lay on the torpedo happened to bear more 

 loosely than usual against that in his hand. 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 passage 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. 



