364} Dr. Faraday's Experimental Researches in Electricity^ xv- 



fleeted, and perhaps a wire heated, by one single discharge of 

 the electric force of the animal. 



1769. I think a few further but brief details of experiments 

 relating to the quantity and disposition of the electricity in 

 and about this wonderful animal will not be out of place in 

 this short account of its powers. 



1 770. When the shock is strong, it is like that of a large 

 Leyden battery charged to a low degree, or that of a good 

 voltaic battery of perhaps one hundred or more pairs of plates, 

 of which the circuit is completed for a moment only. I en- 

 deavoured to form some idea of the quantity of electricity by 

 connecting a large Leyden battery (291.) with two brass balls, 

 above three inches in diameter, placed seven inches apart in 

 a tub of water, so that they might represent the parts of the 

 Gymnotus to which the collectors had been applied; but to 

 lower the intensity of the discharge, eight inches in length of 

 six-fold thick wetted string were interposed elsewhere in the 

 circuit, this being found necessary to prevent the easy occur- 

 rence of the spark at the ends of the collectors (1758.), when 

 they were applied in the water near to the balls, as they had 

 been before to the fish. Being thus arranged, when the bat- 

 tery was strongly charged and discharged, and the hands put 

 into the water near the balls, a shock was felt, much resem- 

 bling that from the fish ; and though the experiments have 

 no pretension to accuracy, yet as the tension could be in 

 some degree imitated by reference to the more or less ready 

 production of a spark, and after that the shock be used to in- 

 dicate whether the quantity was about the same, I think we 

 may conclude that a single medium discharge of the fish is 

 at least equal to the electricity of a Leyden battery of fifteen 

 jars, containing 3500 square inches of glass coated on both 

 sides, charged to its highest degree (291.). This conclusion 

 respecting the great quantity of electricity in a single Gymnotus 

 shock, is in perfect accordance with the degree of deflection 

 which it can produce in a galvanometer needle (367. 860. 

 1761.), and also with the amount of chemical decomposition 

 produced (374. 860. 1763.) in the electrolyzing experiments. 



1771. Great as is the force in a single discharge, the Gym- 

 notus, as Humboldt describes, and as 1 have frequently ex- 

 perienced, gives a double and even a triple shock; and this 

 capability of immediately repeating the effect with scarcely a 

 sensible interval of time, is very important in the considera- 

 tions which must arise hereafter respecting the origin and 

 excitement of the power in the animal. Walsh, Humboldt, 

 Gay-Lussac, and Matteucci have remarked the same thing 

 of the Torpedo, but in a far more striking degree. 



