HISTORY AND PROGRESS. , 15 



the convulsions return whenever he took sparks from the 

 machine.* 



The professor, who was luckily not more learned in elec- 

 trical science than in some of the other branches of physics, 

 was unable to give the explanation of the phenomenon, with 

 which he would probably have contented himself, and have 

 let the matter drop? had he been an experienced electrician. 

 But he was struck by the novelty of the new fact, and he 

 determined to follow it up. 



Galvani thenceforth prosecuted his studies and experi- 

 ments on the electricity of animals, with perseverance, and 

 chance rewarded him for his industry by again coming to 

 his aid. In his experiments on the electricity of frogs, he 

 had occasion to separate the lower parts of the bodies from 

 the upper. Having prepared a frog in the ordinary manner, 

 on one occasion he remarked that on hanging it up to an iron 

 balustrade of his house, by a hook of copper wire passed 

 through part of the dorsal column remaining above the junc- 

 tion of the thighs, it all at once underwent a series of lively 

 convulsions. 



The professor was more than ever astonished, for there was 

 this time no electrical machine to account for the appearance, 

 and he was compelled to take refuge in the hypothesis of 

 what he called " animal electricity," supposing opposite kinds 

 of electricity to exist in the muscles and nerves of the 

 animal. 



In this hypothesis he regarded the muscles and nerves 

 as the charged coatings of a Leyden jar. It is worthy of 

 remark and regret that Galvani should have so thoroughly 

 mistaken the important part played in the affair by the two 

 metals, iron and copper. He regarded these, however, only 

 in the light of a compound conductor, through which the 

 opposite electricities, assumed to exist in the nerves and 

 muscles, discharged themselves. 



It is not a rare thing in the annals of science that mere 

 chance has suggested some great discovery. But we seldom 



* " Aloysii Galvani de Viribus Electricit. in motu musculari Com- 

 mentar.'' p. 2. 



