What is "zograscope"

n. A device used for viewing perspective prints, consisting of a lens and a slanting mirror on a stand.

A zograscope is an optical device for enhancing the sense of depth perception from a flat picture. It consists of a large magnifying lens through which the picture is viewed. Some models have the lens mounted on a stand in front of an angled mirror (Figure 1). This allows someone to sit at a table and to look through the lens at the picture flat on the table. Pictures viewed in this way need to be left-right reversed; this is obvious in the case of writing (as shown in Figure 2). A print made for this purpose is called a vue d'optique or perspective view.

According to Michael Quinion, the origin of the term is lost, but it is also known as a diagonal mirror, as an optical pillar machine, or as an optical diagonal machine.

Zograscopes were popular during the later half of the 18th century as parlour entertainments. Most existing ones from that time are fine furniture, with turned stands, mouldings, brass fittings, and fine finishes.