26o EIGHTEENTH CENTURY. pt. hi. 



several frogs and hung them by copper hooks upon an iron 

 balcony outside his house. As they hung there the wind 

 swayed them to and fro, so that the ends of the legs touched 

 the iron of the balcony; and every time they did so 

 he noticed that the legs were convulsed just as they had 

 been by the electrical machine and the lightning. But this 

 time he could not see that any electricity had come near 

 them from outside, so he supposed that there must be an 

 electric fluid in the leg itself, which passed round every time 

 the two ends of the leg were joined by the metal. These 

 discoveries of Galvani soon became spoken of far and wide 

 under the name of galvanism, and the supposed fluid was 

 called the galvanic fluid. 



Among the celebrated men who were attracted by this 

 new discovery was Alessandro Volta, Professor of Natural 

 Philosophy at the University of Pavia, who was born at 

 Como in 1745, and was at this time a well-known naturalist. 

 Not satisfied with merely reading about Galvani's experi- 

 ments, Volta tried them himself, and he began to suspect 

 that the electricity was not, as Galvani imagined, in the frog's 

 leg, but was produced by the two metals, copper and iron, 

 upon which the legs had been hung, and which were acted 

 upon by the moisture in the flesh. 



Then began a very famous controversy. Volta insisted 

 that the electricity came from the metals, Galvani that it 

 came from the animal. In each new experiment which 

 Galvani brought forward to prove his point, Volta still 

 showed that the electricity could be produced without the 

 animal, until at last Galvani succeeded in finding a test 

 which he thought must silence Volta for ever. He found 

 that by laying bare a nerve of the leg of a frog, called the 

 ' crural nerve,' and bringing the end of it to the outside of 

 the muscles of the leg, he could produce the convulsions 



