360 Dr. Faraday's Experimental Researches in Electricity, xv. 



common in the Llanos de Caracas (near Calabozo), in all the 

 small rivers which flow into the Orinoco, in English, French 

 or Dutch Guiana, is not of difficult transportation. We lost 

 them so soon at Paris because they were too much fatigued 

 (by experiments) immediately after their arrival. MM. Nor- 

 derling and Fahlberg retained them alive at Paris above four 

 months. I would advise that they be transported from Suri- 

 nam (from Essequibo, Demerara, Cayenne) in summer, 

 for the Gymnotus in its native conntry lives in water of 25° 

 centigrade (or 77° Fahr.). Some are five feet in length, but 

 I would advise that such as are about twenty-seven or twenty- 

 eight inches in length be chosen. Their power varies with 

 their food, and their state of rest. Having but a small sto- 

 mach they eat little and often, their food being cooked meat, 

 not salted, small fish, or even bread. Trial should be made 

 of their strength and the fit kind of nourishment before they 

 are shipped, and those fish only selected already accustomed 

 to their prison. I retained them in a box or trough about four 

 feet long, and sixteen inches wide and deep. The water must 

 he fresh, and be changed every three or four days : the fish 

 must not be prevented from coming to the surface, for they 

 like to swallow air. A net should be put over and round the 

 trough, for the Gymnotus often springs out of the water. 

 These are all the directions that I can give you. It is, how- 

 ever, important that the animal should not be tormented 

 or fatigued, for it becomes exhausted by frequent electric ex- 

 plosions. Several Gymnoti may be retained in the same 

 trough." 



1754'. A Gymnotus has lately been brought to this country 

 by Mr. Porter, and purchased by the proprietors of the Gal- 

 lery in Adelaide Street; they immediately most liberally of- 

 fered me the liberty of experimenting with the fish for scien- 

 tific purposes ; they placed it for the time exclusively at my 

 disposal, that (in accordance with Humboldt's directions 

 (1753.)) its powers might not be impaired ; only desiring me 

 to have a regard for its life and health. I was not slow to 

 take advantage of their wish to forward the interests of sci- 

 ence, and with many thanks accepted their offer. With this 

 Gymnotus, having the kind assistance of Mr. Bradley of the 

 Gallery, Mr, Gassiot, and occasionally other gendemen, as 

 Professors Daniel 1, Owen, and Whealstone, I have obtained 

 every proof of the identity of its power with common electri- 

 city (265. 351, &c.). All of these had been obtained before 

 with the Torpedo (1750.), and some, as the shock, circuit, 

 and spark (1751.), with the Gymnotus; but still I think a 

 brief account of the results will be acceptable to the Royal So- 



