Electrical chimes, 1780s.
© Science Museum / Science & Society Picture Library
Electric chimes were a common feature of 18th century lecture courses. These were probably made by the younger George Adams, instrument maker to the king, for the Prince of Wales, later George IV. They use the same principle as the electric orrery: charge is made to stream from metal points creating an electric wind. In this case the wind turns the fly so that a bras clapper strikes the bells in turn, sounding the notes of an octave.