A Foucault Switch, a type of automatic circuit interrupter used widely in the late 19th century & invented by the French physicist Jean Bernard Léon Foucault (1819-1868). During that century, scientists and engineers created new uses for electricity & developed increasingly sophisticated circuit elements to control instruments & electric phenomena. Among these elements were different interrupters—basic components that open or close an electric circuit to regulate conduction.
Battery, 1800 For the battery we must thank the frog. In the 1780s, the Italian physicist Luigi Galvani discovered that a dead frog's leg would twitch when he touched it with two pieces of metal. Galvani had created a crude circuit and the phenomenon was taken up by his friend, the aristocratic Professor Alessandro Volta, whose voltaic cells stacked in a Voltaic pile amazed Napoleon. The pile was also the first battery, whose successors power more than a third of the gadgets on this list.