a guitar for which a mirror is instantly relocated such that it reflects sunlight in a consistent way. It's used in combination with a pyrheliometer to create constant measurements of solar radiation.
A device which includes an airplane mirror which converts in order to hold showing sunlight toward a predetermined target, compensating for sun's evident movements when you look at the sky. The mark might a physical item, distant from the heliostat, or a direction in room, and is almost always fixed in accordance with the heliostat, so the light is mirrored in a hard and fast way.
a guitar comprising a mirror moved by clockwork, wherein a sunbeam is manufactured apparently fixed, when you are steadily directed to a single spot during the whole of its diurnal period; additionally, a geodetic heliotrope.
An instrument consisting of a mirror held by clockwork in such a way as to mirror natural sunlight in a fixed path. The name is also incorrectly put on a porte-lumière.