6 HISTOEICAL SKETCH. CHAP. I- 



stances by means of which the circuit was completed. 

 Both Galvani and Volta considered, however, that 

 the effect, the contraction of the muscle, was evidence 

 of the manifestation of electrical excitement; in 

 fact, the limb was then, as it is employed at the 

 present day, an indicator of electrical action. Both 

 were wrong in their exclusive notions respecting the 

 origin of the power; Galvani in denying or over- 

 looking the circumstance, that the power might 

 partly arise from the contact of the heterogeneous 

 substances forming the circuit ; Volta, on the other 

 hand, in denying the origin of the power in the 

 animal body. 



Humboldt", from his numerous experiments, came 

 to the conclusion, that the effects could not be en- 

 tirely referred to the mere, contact of the metals 

 as suggested by Volta, but that they were partly due 

 to some cause originating in the animal. 



I shall now refer to a communication pubhshed 

 at this period, in which will be found a concise view 

 of the then state of knowledge upon the subject. 

 It is of some value, inasmuch as it is a letter written 

 by Vassali Eandi, at that time one of the celebrated 

 professors at Turin, to M. Delamethbie, then Secre- 

 tary to the Eoyal Academy of Paris, who requested 

 his opinion " upon galvanism, and the origin of 

 animal electricity*." The position these two 



" Experiences sur le GalTonisme, Paris, 1799. 



* Lettre de Vassali Eandi, k J. C. Delamethbie. Svt U 



