Alesandro Volta, Italian physicist and inventor, c 1820.
© Science Museum / Science & Society Picture Library
Portrait engraving by Giovita Garavaglia of Count Alesandro Giuseppe Anastasio Volta (1745-1827). Volta was the inventor of the voltaic pile, an early battery and the first source of current electricity. It consisted of two different metals, separated by chemicals in order to enable a flow of electricity. In 1775, he invented the electrophorus, a precursor of the induction machine, and in 1777 an 'inflammable air' electric pistol. The SI (international standard) unit of electromotive force, the volt (V), is named after him. Illustration from his 'Le opere di Alesandro Volta' (The works of Alesandro Volta), published in Milan, 1918-1929.