The Gymnotus experimented 'with. 359 



mined by the united and successive labours of Walsh*, Ca- 

 vendishf, GalvaniJ, Gardini§, Humboldt and Gay-Lussac ||, 

 Toddlf, Sir Humphry Davy**, Dr.Davyft) Becquerel ij:^, 

 and Matteucci§§. 



175 1 . TheGymnotus has also been experimented with for the 

 same purpose, and the investigations of Williamson || ||, Gar- 

 den^^, Humboldt***, Fahlbergt ft and Guisan:}: JJj have gone 

 very far in showing the identity of the electric force in this 

 animal with the electricity excited by ordinary means; and 

 the two latter philosophers have even obtained the spark. 



1752. As an animal fitted for the further investigation of 

 this refined branch of science, the Gymnotus seems, in certain 

 respects, better adapted than the Torpedo, especially (as 

 Humboldt has remarked) in its power of bearing confinement, 

 and capability of being preserved alive and in health for a 

 long period. A Gymnotus has been kept for several months 

 in activity, whereas Dr. Davy could not preserve Torpedos 

 above twelve or fifteen days ; and Matteucci was not able out 

 of 116 such fish to keep one living above three days, though 

 every circumstance favourable to their preservation was at- 

 tended to II II 1 1. To obtain Gymnoti has therefore been a mat- 

 ter of consequence; and being stimulated, as much as I was 

 honoured, by very kind communications from Baron Hum- 

 boldt, I in the year 1835 applied to the Colonial Office, where 

 I was promised every assistance in procuring some of these 

 fishes, and continually expect to receive either news of them 

 or the animals themselves. 



1753. Since that time Sir Everard Home has also moved 

 a friend to send some Gymnoti over, which are to be con- 

 signed to His Royal Highness our late President; and other 

 gentlemen are also engaged in the same work. This- spirit 

 induces me to insert in the present communication that part 

 of the letter from Baron Humboldt which I received as an 

 answer to my inquiry of how they were best to be conveyed 

 across the Atlantic. He says, " The Gymnotus, which is 



* Philosophical Transactions, 1773, p. 461. \ Ibid. 1776, p. 196. 



:j: Aldini's Essai sur le Galvanisme, ii. 61. 



§ De Electrici Ignis Natura, §. 71. Mantua, 1792. 



II Annates de Chimie, xiv. 15. ^ Phil- Trans., 1816, p. 120. [or 



Phil. Mag., First Series, vol. xlviii, p. 14.] "♦* Ibid. 1829, p. 15. [or 



Phil. Mag. and Annals, vol. vi. p. 81.] ft Ibid. 1832, p. 259; and 



1834, p. 531. [see Lond. and Edinb. Phil. Mag., vol. i. p. 67 ; xi. p. 57.] 



XX Traite de I'Electricite, iv. 264. §§ Biblioth^qne Universelle, 



18.37, torn. xii. 163. [see Lond. and Edinb. Phil. Mag., vol. xii. p. 196,] 



II II Phil. Trans., 1775, p. 94. It Ibid. 1775, p. 102. 



*** Personal Narrative, chap. xvii. f+f Swedish Transactions, 1801, 

 pp. 122. 156. XXX De Gyimnoto Electrico. Tubingen, 1819. 



II II II Bibliotheque Universelle, 1837, xii. p. 174. 



