manograph

English

Etymology

From Ancient Greek μανός (manós, “thin, rare”) +‎ -graph.

Noun

manograph (plural manographs)

1. An optical device for making pressure volume diagrams for high-speed engines, involving a light-tight box or camera having at one end a small convex mirror reflecting a beam of light onto the ground glass or photographic plate at the other end. The mirror is pivoted so that it can be moved so as to copy the motion of the engine piston on a smaller scale.
   • 1909, Minutes of Proceedings of the Institution of Civil Engineers:

     In addition to the ordinary type of indicator, the Author describes the Hospitalier and the Schultze manographs, in which the diagram is produced photographically by reflecting a beam of light from a mirror attached to a diaphragm […]

Translations

optical device

• French: manographe (fr)