optigraph

Century Dictionary and Cyclopedia

1. n. A form of telescope constructed for the purpose of copying landscapes, etc. It is suspended vertically in gimbals by the object-end, beneath a fixed diagonal plane mirror, which reflects the rays from the objects to be drawn through the object-glass of the instrument to a speculum, and thence through the eye-glass to the eye. Between the eye and the speculum is a piece of parallel-faced glass with a small dot on its center, exactly in the focus of the eyeglass. This dot is made to pass over the outlines of an object, and a pencil fixed at the eye-end traces the delineation on paper.

Wiktionary

1. n. A telescope with a diagonal eyepiece, suspended vertically in gimbals by the object end beneath a fixed diagonal plane mirror. It is used for delineating landscapes by means of an attached pencil.

GNU Webster's 1913

1. n. A telescope with a diagonal eyepiece, suspended vertically in gimbals by the object end beneath a fixed diagonal plane mirror. It is used for delineating landscapes, by means of a pencil at the eye end which leaves the delineation on paper.