- 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; -- commonly called simply the camera.