Fruit-powered clock, 1998.
© Science Museum / Science & Society Picture Library
Using Alessandro Volta's (1745-1827) original design for a battery, this clock is powered by a fruit or vegetable which provides acid paste, or electrolyte. Volta was an Italian physicist and the inventor of the voltaic pile, the first battery. This consisted of two different metals, separated by chemicals, in order to enable a flow of electricity. It had previously been thought by the Italian scientist Luigi Galvani (1737-1798 ) that animal tissue was necessary to generate electricity. Volta has the unit of electromotive force, the 'volt', named after him.