Italian anatomist Luigi Galvani (1737-1798) demonstrates his experiments with frog muscles in this illustration from a children's book on electricity, circa 1900. Galvani noticed that the muscles of dissected frog legs twitched wildly when struck by an electric spark. Since lightning had been shown to be electrical in nature, Galvani reasoned that frog muscles might twitch during a thunderstorm. He therefore put samples on brass hooks & hung them outside on an iron latticework. They were found to twitch in the absence of lightning: in fact whenever they formed a contact between the two different metals. This effect was later used by Volta to produce the first battery.