Friction machine, 1762.
© Science Museum / Science & Society Picture Library
This machine shows that friction is due to weight acting on the moving parts, and also demonstrates the advantage of 'friction wheels': the rollers on which the axle rests. When the spoked wheel was spun, it would turn 'more than the space of a mile', according to George Adams, instrument maker to the king, who made the machine. Alternatively a watch spring could make the wheel oscillate. Friction was provided using the small bras lever and the number of oscillations with and without friction compared.