ELECTRICITY. 



477 



IVseriptire fluids seemed in both cases necessary to the develope- 

 F.leetririty. m ent of the electrical effects. Volta himself believed, 

 *^Y" P/ that among the humid substances of which the elec- 

 trical organ of the torpedo is composed, some are adapt- 

 ed to excite the electric virtue by their mutual con- 

 tact, and others to transmit it ; and hence he supposes, 

 that the superposition of the different cells formed of 

 those substances corresponds to that of the metallic 

 and moist conductors, of which the pile consists. This 

 analogy, however, is more imaginary than real. Messr* 

 Humboldt and Gay Lussac remark, " that they would 

 rather be inclined to compare their action to a chain of 

 small Ley den phials than to the pile of Volta."- - - " The 

 nerves," say they, " without doubt, act the chief part in 

 the production of these phenomena; and the physiologist, 

 who takes a general and enlarged view of the vital ac- 

 tion;, would, with reason, oppose the ideas of the phi- 

 losopher, who conceives he can explain the whole by 

 the contact of the albumino-gelatinous pulp with the 

 * tendinous septa which nature has conferred in the for- 

 mation of the organs of the torpedo." 



For further information on this subject, see Redi j> 

 perimenla circa res diversas naturates. Lorenzini Os- 

 servationi intorno alle Torpedini. Fiorenze 16~8, an ac- 

 count of which is given in the Phil. Trans. 168 1, No. 1, 

 p. 42. Reaumur, Mem, Acad. Par. 1714, p. 344. 

 Bancroft's Natural Historyof Guiana, p. 19-t. Duhamel, 

 Traite general du Pechet, el Histoire des poissons, torn, 

 iii. sect. i*. Walsh, Phil. Trans. 1773, p. 461. Id. 

 1775, p. 465. Hunter, Phil. Trans. 1773, p. 481. 

 Hunter on the Animal Economy. Ingenhouz, Phil. 

 Tram. 1115, p. 1. Pringle's Discourse on the Tor- 

 pedo, Lend. 1775. Cavendish, PhiL Trans. 1776, 

 p. 196. Geoffrey, Annales du Museum, a" Hist. Nat. 

 p. 392, or in Tilloch's Philosophical Magazine, vol. 

 xv. p. 126. Volta, Annales de Ckimie, 1802, 30th 

 Frimaire, p. 255. Humboldt and Gay Lussac, An- 

 nalet de Chimie, 1805, No. 166, or in Phil. Mag. 

 1806, vol. xxiii. p. 356. Nicholson's Philosophical 

 Journal, vol. i. 4to, p. 355. Hauy, Traite de Phy- 

 sique, vol. ii. p. 44, Dr O. Gregory's Translation. 

 Bryant, American Transactions vol. ii. p. 166. Vassal! 

 Eandi, Journal de Physique, vol. xlix. p. 69. Lettre 

 de M. 1'Abbe Spallanzuni a M. Le Marquis de Lucche- 

 sini in Rozier's 0/iservalions sur la Physique, torn, xxiii. 

 . p. 217- Bertholon, De L' Eiectricite du Corps llumain, 



torn. i. p. 172. 



2. On the Electricity of the Gymnotus Eleclricus. 



On the dec- The gymnotus electricus, or the electrical eel of 

 tricity of the Surinam, possesses electrical properties different from 

 nymnntui those of the torpedo. The properties of this fish were 

 electricus. g rgt n^g known to philosophers by M. Richer, upon 

 his return from measuring the length of the pendulum 

 at Cayenne. This fish was mentioned by Condamine, un- 

 clerthe name of I'uratjua.and its electrical properties have 

 l>een successively noticed by 1'errere, Fermin, Bancroft, 

 and Vanderlott, the latter of whom speaks of its medi- 

 cal effects. At the desire of the Academy of Sciences, 

 the experiments of Vanderlott were repeated and con- 

 firmed by M. Bajon, at Cayenne, in 1773. The most 

 correct experiment*, however, which have been made 

 with it we owe to Dr Hugh Williamson of Philadelphia, 

 I )r( iarden of Charlestown, and Mr Walsh. The follow- 

 ing are the most interesting results which they obtained. 



1. When the eel was touched with the hand, a shock 

 was experienced in the fingers, and often in the wrist 

 and elbow. 



2. When the gymnotus was touched with an iron 



the gymno- 



rod 12 inches long, the shock wag experienced in the Descriptive 

 finger and thumb which held the rod. Electricity 



3. If the hand of any person is held in the water, at 



the distance of three feet, when another person provokes Wilham- 

 the eel by touching it, he will feel a less painful sensa- 

 tion than if he had touched the eel itself. 



4. When a cat-fish was thrown into the water to the tus. 

 eel, Dr Williamson put his hand in the water at some 

 distance, and watched what took place. The gymnotus 

 swam up to the cat, but turned away without offer- 

 ing any violence. It soon returned, however, and 

 viewing the cat-fish for some seconds, gave it a 

 shock which made it turn up its belly and continue 

 motionless. At this time Dr Williamson felt a shock 



in his fingers, as in experiment 3. When any of the 

 fish that were thus rendered motionless by the eel were 

 taken into another vessel, they always recovered. 



5. When the eel was touched and provoked with one 

 hand, and when the other was held in the water at a 

 small distance, a shock passed through both arms, as with 

 the Leyden phial. 



6. When the end of a wet stick was held in the water 

 with one hand, and the eel was touched with the other, 

 a shock passed through both arms. 



7. When the preceding experiment was made by two 

 persons joining hands, the shock passed through them 

 both. 



8. When one of two persons joining hands touched 

 the head roughly, while the other touched the tail gen- 

 tly, they both received a severe shock. 



9. When the first of 8 or 10 persons joining hands 

 touched the eel, while the last putmVhand in the wa- 

 ter at some distance from it, they all received a gentle 

 shock. 



10. When the first of the 8 pinched the tail, while 

 the last touched the head, they all received a severe 

 shock. 



1 1 . When two persons kid hold of the two extremi- 

 ties of a brass chain, and one of them put his hand in 

 the water, while the other touched and irritated the 

 eel, the shock passed through both. 



12. If a silk handkerchief is wrapped round the 

 hand, and the eel is touched with it, no shock is expe- 

 rienced, though another person will feel the shock, who 

 puts his hand into the water at a little distance from 

 the eel. 



IS. The communication between two persons was 

 formed by various bodies, such as charcoal, iron, brass, 

 dry wood, glass, silk, &c. and it was always found that 

 the shock of the eel was conveyed through those sub- 

 stances that conduct common electricity, while it refused 

 to pass through non-conductors. 



14. The shock was not conveyed by a brass chain, 

 unless the chain was stretched, or the shock severe. 



15. When an insulated person was electrified by the 

 eel, he exhibited no marks of electricity, nor did cork 

 balls diverge when suspended by silk threads over the 

 eel's back, or when touched by the insulated person 

 when he received the shock. 



16. A person, holding a Leyden phial in one hand, 

 put his hand to the tail of the fish, while another, hold- 

 ing a short wire in one hand that communicated with 

 the inside of the phial, grasped the fish near its head, 

 he received a severe shock in his hand and arms. 



17. Two pieces of brass wire, about one-sixth of an 

 iuch thick, were rounded at the ends, and fixed at the 

 distance of the hundredth part of an inch in a frame of 

 wood, then when one person held the farther end of one 

 of the wires, while a second person held the end of 



