Folding inclined plane, about 1750. Made from mahogany. It is 3 feet in length and marked in quarter inches with every half inch numbered.

This is inclined plane is thought to be one of the two wooden inclined planes listed in the Queen's catalogue and as such is thought to be part of Stephen Demainbray's collection of demonstration equipment. That collection became amalgamated into King George III's own collection when Demainbray began working at Kew Observatory.