An apparatus in which the images of external objects, formed by a convex lens or a concave mirror, are thrown on a paper or other white surface placed in the focus of the lens or mirror within a darkened chamber, or box, so that the outlines may be traced. An apparatus in which the image of an external object or objects is, by means of lenses, thrown upon a sensitized plate or surface placed at the back of an extensible darkened box or chamber variously modified
2
Plane or flat on one side, and convex on the other; as, a plano-convex lens
3
A refracting telescope, in which the image to be viewed is formed by the refraction of light in passing through a convex lens.
