Alessandro Volta (1745–1827) was an Italian physicist who built the world's first battery — the first device that could push a steady, reliable electric current. Before him, electricity was a fleeting spark; after him, it was a tool you could switch on.
Volta stacked discs of two different metals with salty cardboard between them, and out flowed a
continuous current — the "voltaic pile." It was the first
Volta's rival Luigi Galvani had noticed dead frog legs twitching when touched by metal, and declared he'd found a mysterious "animal electricity." Volta disagreed: the electricity, he argued, came from the two metals, not the frog. To prove it, he threw the frogs out entirely and built the battery from metal and brine alone — and it worked beautifully. The friendly feud pushed the whole science forward. Volta was such a star that Napoleon himself insisted on seeing the pile demonstrated in person.