Luigi Galvani found out that dead frogs twitched when connected to an electrical friction machine. When frogs’ legs were hung from a metal railing, they also twitched. Galvani thought that the nerves and muscles of the frog must contain an electrical power that caused the dead limbs to move.
Galvani was wrong. He used brass hooks to hang the frogs’ legs from the iron railings. The two metals, not the frogs were producing electricity, and the legs were acting as conductors. Naively Galvani discovered the principle of the electric cell.