Camera lucida : An instrument which by means of a prism of a peculiar form, or an arrangement of mirrors, causes an apparent image of an external object or objects to appear as if projected upon a plane surface, as of paper or canvas, so that the outlines may conveniently traced. It is generally used with the microscope.

Example:


Taxonomy
camera lucida, drawing products, free encyclopedia, Latin, superimposition, evidence, dark room, arrangement, paper, photo, illustration, camera obscura, search, Roland Barthes, engraving, double exposure, duplicate key, perspective.

Defination from the web:
camera lucida performs an optical superimposition of the subject being viewed upon the surface upon which the artist is drawing. ... The camera lucida was patented in 1807 by William Hyde Wollaston. There seems to be evidence that the camera lucida was actually nothing but a ...