Where made: 
27 × 6 × 3 cm

Wollaston pattern camera lucida made in France.

The device allows simultaneous viewing of a scene and a piece of paper on a desk, so that a pencil can follow the outlines of the object being drawn. One of a  series of lenses can be placed in the scene optical path to allow both scene and paper to be in focus for the eye simultaneously. The eye needs to be maintained very close to the edge of a small prism so that the user can see around and through it at the same time, so it is not easy to use without practice.