Note:  Do not rely on this information. It is very old.

Camera Lucida

Camera Lucida, an arrangement with many modifications, invented by Wollaston, to produce an image of an object on a plane surface such as a sheet of paper. If this image be traced out with a pencil, a correct delineation of the object results. The diversion of the rays of light necessary to produce this apparent alteration in the direction of the object is generally effected by total reflection from the inner surface of a glass prism. It may also be produced by simple reflection at an angle of 45° from a plane piece of glass held over the paper at the same angle. When the operator places himself directly over the paper he will see the image thereon.