10 HISTORY OF GALVANISM. 



silver, placed alternately upon each other ; a con- 

 struction which may be regarded as an approxima- 

 tion to the apparatus afterwards discovered by 

 Volta. 



Voita's let- In the same year in which Fowler's Essay was 

 ers, 1793. p^igh^ a verv va l ua ble communication appeared 

 in the Philosophical Transactions of London, from 

 the pen of Professor Volta, of Pavia, in the form 

 of letters to CavaLlo. He gives a luminous ac- 

 count of Galvani's discovery, and adds many cu- 

 rious experiments and observations of his own. 

 He attempted, and with complete success, to 

 overthrow Galvani's opinion, that the animal body 

 bears an analogy to the Leyden phial, its different 

 parts being in opposite states of electricity. He 

 supposed, that for the production of the effect it 

 was essential to have two different metals ; and 

 hence he arrived at the important conclusion, 

 which may be regarded as leading to all his future 

 discoveries, that the muscular contractions are 

 produced by small portions of electricity, that are 

 liberated by the action of the metals upon each 

 other. Another point which Volta established 

 was, that the nerve is the organ on which the 

 galvanic influence immediately acts ; but he found 

 that if a part of a muscle be laid upon two differ- 

 ent metals, and these be made to communicate, a 

 contraction is produced. This probably depends 

 upon the nervous matter that is dispersed through 

 the muscles, and also upon the moisture that is 

 always present, and which serves to conduct the 



