44 GALVANIC ELECTRICITY. 



spheric electricity. With this view la raised a conductor on the roof 

 of his house, from \vhich he brought an iron wire into his room. 

 To this he attached metal conductors, connected with the nerves of 

 the anim.il> destined to be the subject of his experiment* ; and to 

 their legs he faMen-d wires which reached the floor. These cxpe- 

 rimcnts were not confined to frogs alone. Di fie rent animals, both 

 of cold and warm Wood, were subjected to them; and in all ot 

 them considerable movements were excited whenever it lightened. 

 These preceded thunder, and corresponded with its intensity and re. 

 petition ; and even when no lightning appeared, the movements 

 took place when any stormy cloud passed over the apparatus. That 

 all these appearances were produced by the electric fluid was ob- 

 vious. 



Having soon after this suspended some frogs from the iron pali- 

 sades which surrounded his garden, by means of metallic hooks 

 fixed in the spines of their backs, he observed that their muscles 

 contracted frequently and involuntarily, as if from a shock of elec- 

 tricity. Not doubting that the contractions depended on the elec- 

 tric fluid, he at first suspected that they were connected with changes 

 in the state of the atmosphere. He soon found, however, that this 

 was not the case; and having varied, in many different ways, the 

 circumstances in which the frogs were placed, he at length disco, 

 vered that he could produce the movements at pleasure by touching 

 the animals with two different metals, which at the same time, 

 touched one another either immediately or by the intervention of 

 some other substance capable of conducting electricity. 

 , All the experiments that have been made may be reduced to the 

 / following, which will give the otherwise uninformed reader a pre- 

 / else notion of the subject. 



/ Lay bare about an inch of a great nerve, h -ading to any limb or 

 / nuiM-.Ie. Let that end of the bared part which is farthest from the 

 I limb be in close contact with a hit of zinc. Touch the xinc with a 

 o/ bit of silver, while another part of the silver touches, either the 

 ' naked nerve, if not dry, or, whether it be dry or not, the limb or 

 muscle to which it leads. Violent contractions are produced in 

 the limb or muscle, but not in any muscle on the other side of the 

 zinc. 



Or, touch the bared uervc with a piece of zinc, and touch, with 

 a piece of MJ\er, either the bared nerve, or the limb; no convulsion 

 i- ohH-rved, till the /inc and silver are also made to touch each 

 other* 



