Additional Nofa^ ?m 



bacV, nenr its hcad^ nnd another of tlu* opposite Imnd into iLf 

 water near its tail. In their native country they are said to ex- 

 ceed twenty feet in length, and kill any man who approaclies iheni 

 in a hostile manner. It is not only to escape its enemies that 

 this surprising power of the iish is useil, but iilso to take its prev ; 

 which it does by benumbing them, and then devourhig them \m' ■ 

 fore they have time to recover, or by perfectly killing them at 

 once J for the quantity of the power seems to be determined by 

 tlie will of the animal j as it sometimes strikes a tibh twice before 

 it is sufficiently benumbed to be easily swallowed. 



The organs productive of this wonderful accumuhlion of elec- 

 tric matter have been accurately dissected and described by Mr. .T. 

 Hunter, Fhilos. Trans, vol. Ixv. They are so di\ ided by nKinbranc* 

 as to compose a veiy extensive surface, and are supplied witli 

 many pairs of nerves, larger than any other nerves of the body : 

 but how so large a quantity is so qpiekly accunu\lated as to pro- 

 duce such amazing effects in a fluid ill adapted for the purpose, 

 is not yet satisfactorily explained. The Tcw7jtfr/t> possesses a simi- 

 lar power in a less degree, as was shown by Mr. Walbh : so does 

 another fish lately described by Mr. Paterson. — Phil. Tram, vol. 

 ixxxvi. Botanic Garden, part I, canto i, p. 12, note. 



Note (H), page 36. — Four epochas may be observed in the. 

 history of Galvanism, each of them distinguished by the develop- 

 ment of important facts. The first M'as formed by the publica- 

 tion of the fundamental Galvanic fact, viz. the production of 

 muscular contraction by the application of metals to the nenes 

 and muscles of animals, and which was entirely limited to orga- 

 nised bodies. The second may be derived from the discovery of 

 the Galvanic influence in inorganic matter. The researches of 

 Fabroni, Dr. Ash, and Creve, exhibiting the i)eculiar action ot 

 metals in contact with each other upon water, demonstrated the 

 production of the Galvanic influence in combinations wholly com- 

 posed of inorganic matter, and thereby connected it witli the 

 general principles of ph}'sics. The third epocha in the history of 

 Galvanism is founded on the discovery of the means of accumu 

 lating this influence by the battcrj/ or pile of \o\tii, which paved 

 the way for a distinct exhibition of the analogy between C-rl- 

 vanism and conmion electricity. The fuurth arises from the dis- 

 covery of the chcmiccd agencies of Galvanism. In the pro.-ecutiori 

 of this last train of inquiry, the principal degree of praise is due 

 to the British experimenters ^ and, among the^e, chiefly to Messrs 



