Compound engine, 1762.
© Science Museum / Science & Society Picture Library
George Adams, instrument maker to the king, described this instrument as 'one of the simplest and most elegant compound engines I have ever seen'. It was he who made it. It combines three simple machines: two wheels and axles and a screw. The load was suspended from the axle at the base and hung through the centre of the frame. It was lifted by a 'power' on the large spoked wheel. In theory a weight 6000 times that of the applied force or 'power' could be raised but friction greatly reduced this figure in reality.