Model demonstrating the principle of a camera obscura, unknown maker, 1752, but once belonged to Stephen Demainbray.

Model showing the principle of a camera obscura. This belonged to Stephen Demainbray and was used by him in his lectures on natural philosophy. It was sketched by Pere Chabrol, an attendee of one of the lectures in 1753.

The light rays, represented by threads, start from the coloured cross on the right, through the lens and are then reflected by the 45 degree mirror onto the horizontal screen above it. The cross on the left demonstrates the path of the light rays had the mirror not been present. 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. It was itemised in the Queen's catalogue.