Experiments on (he Torpedo. 357 



rilcate those shocks tcruied electric, althougli t'.ic feelino; is 

 very different from that which is occasioned hv the dis- 

 charge of a Leydeii phial. Having at band no other work 

 besides that of Aldini, in which he has combined into one 

 view the beautiful researches of Geoffroy witii those of 

 Spallanzani and Galvani, we shall not have it in our oower 

 to compare our own labours with those of preceduig phi- 

 losophers. 



1. Although the power of the torpedo cannot be com- 

 pared to that of the gvmnotus, it is not less capable of oc- 

 casioning disagreeable sensations. A person much in the 

 custom of receiving electric shocks, supports with some 

 difficulty the shock of a torpedo 14 inches long, and in a 

 state of perfect vigour. The gymnotus communicates its 

 influence under water, unless when much weakened. 



M. Gay-Lussac has observed, that the action of the tor- 

 pedo in this condition is not perceptible until it is raised ' 

 above the surface of the water. It is with this fish, as with 

 frogs on which Galvanic experiments are made : the cir- 

 cumstances under which the contraction takes place, vary 

 according to the degree of excitability in the organs. 



2. I have remarked, while in South America, that the 

 gymnotus gives the niost frightful shocks without making 

 any external motion of the eyes, head, or fins : it moves no 

 more than one person communicating an idea or sensation 

 to another. But the torpedo, on the rontrarv, moves its 

 pectoral fins in a convulsive manner before each shock ; 

 and the violence of the stroke isalwavs proportioned to the 

 extent of the surface of contact, 



3. The organs of the torpedo, or gvmnotns, cannot be 

 discharged by us at will, like a Leyden phial or a Galvanic 

 pile ; nor does the electric fish imiformlv conmiunicate a 

 shock when touched. It must be irritated that it mav give 

 its stroke; for this action depends upon tlie will of the 

 animal, which in all probability docs not always keep it^ 

 electric organs charged : it charges them, however, with 

 astonishing celerity, and is thus able to give a long scries 

 of shocks. 



4. The shock is felt, provided the animal is disposed to 

 give it, when a single finger' is appljcd to a single surface of 

 the electric organs ; or. when the two hands are placed one 

 on the upper and the other on its under surface at the same 

 lime. And in cither of these cases the shock is equally 

 communicated, whether the person be insulated or not. 



b. If a person while insulated touches the torpedo with 



his finger, it is indispensably necessary that the finger be in 



Z 3 immediate 



