Source : Webster's Revised Unabridged Dictionary (1913)

Oroheliograph \Or`o*he"li*o*graph\, n. [Gr. ? mountain + helio-
   + -graph.] (Photog.)
   A camera for obtaining a circular panoramic view of the
   horizon. The photographic plate is placed horizontally with a
   vertical lens above. A mirror of peculiar shape reflects
   light from the entire horizon to the lens, by means of which
   it is focused upon the plate.