Friction demonstration engine, George Graham

Demonstration of friction bearings made by George Graham, Fleet Street, London, before 1751. Once belonged to Stephen Demainbray.

This machine belonged to Stephen Demainbray and was used by him in his lectures on natural philosophy. It had a spiral spring which was attached to the base and the axle. When it was wound and released the wheel made oscillations and the number of these could be counted when the axle rested on the friction wheels. The spring could also be removed, the wheel spun and the time taken for the wheel to come to a rest measured. Demainbray worked as superintendent at the King's observatory at Kew from 1768 and his collection of instruments and apparatus was absorbed into the King's own collection