Camera lucida

device that uses a prism and mirrors to project the image of an object onto a flat surface so that it may be traced

A camera lucida is an optical device used as a drawing aid by artists. It was patented in 1806 by William Hyde Wollaston. There seems to be evidence that the camera lucida was actually nothing but a reinvention of a device clearly described 200 years earlier by Johannes Kepler in his Dioptrice (1611). By the 19th century, Kepler’s description had totally fallen into oblivion, so that nobody challenged Wollaston’s claim. The term "camera lucida" is Wollaston‘s. (cf. Edmund Hoppe, Geschichte der Optik, Leipzig 1926)
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Noun
1. an optical device consisting of an attachment that enables an observer to view simultaneously the image and a drawing surface for sketching it
(hypernym) optical device
(part-holonym) microscope

n. camera lucida, device that uses a prism and mirrors to project the image of an object onto a flat surface so that it may be traced

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.