82 Sir Humphry Davy's Account of 



Naples, in May 1815, two small torpedos alive, I passed the 

 shocks through the interrupted circuit made by silver wire 

 through water, without being able to perceive the slightest 

 decomposition of that fluid ; and I repeated the same experi- 

 ments at Mola di Gaeta, with an apparatus in which the smallest 

 possible surface of silver was exposed, and in which good con- 

 ductors, such as solutions of potassa and sulphuric acid, were 

 made to connect the circuit ; but with the same negative re- 

 sults. 



Having obtained a larger torpedo at Rimini in June in the 

 same year, I repeated the experiments, using all the precau- 

 tions I could imagine, with like results ; and at the same time 

 I passed the shock through a very small circuit, which was 

 completed by a quarter of an inch of extremely fine silver 

 wire, drawn by the late Mr. Cavendish for using in a micro- 

 meter, and which was less than the ^ J^ ^dth of an inch in dia- 

 meter ; but no ignition of the wire took place. It appeared to 

 me after these experiments, that the comparison of the organ 

 of the torpedo to an electrical battery weakly charged, and of 

 which the charged surfaces were imperfect conductors, such 

 as water, was more correct than that of the comparison to the 

 pile : but on mentioning my researches to Signor Volta, with 

 whom I passed some time at Milan that summer, he showed 

 me another form of his instrument, which appeared to him 

 to fulfill the conditions of the organs of the torpedo ; a pile, 

 of which the fluid substance was a very imperfect conductor, 

 such as honey or a strong saccharine extract, which required 

 a certain time to become charged, and which did not decom- 

 pose water, though when charged it communicated weak 

 shocks. 



The discovery of CErsted of the effects of voltaic electricity 

 on the magnetic needle, made me desirous to ascertain if the 

 electricity of living animals possessed this power ; and after 

 several vain attempts to procure living torpedos sufficiently 

 strong and vigorous to give powerful shocks, I succeeded in 

 October of this year, through the kind assistance of George 

 During, Esq., His Majesty's Consul at Trieste, in obtaining 

 two lively and recently caught torpedos, one a foot long, the 

 other smaller. I passed the shocks from the largest of these 

 animals a number of times through the circuit of an extremely 

 delicate magnetic electrometer, (of the same kind, but more 

 sensible, than that I have described in my last paper on the 

 electro-chemical phaenomena, which the Royal Society has ho- 

 noured with a place in their Transactions for 1826,) but with- 

 out perceiving the slightest deviation of or effect on the needle ; 

 and I convinced myself that the circuit was perfect, by making 



my 



