from
The Collaborative International Dictionary of English v.0.48
Siderostat \Sid"er*o*stat\, n. [L. sidus, sideris, a star + Gr.
??? standing, fixed, fr. ???? to place.] (Astron.)
An apparatus consisting essentially of a mirror moved by
clockwork so as to throw the rays of the sun or a star in a
fixed direction; -- a more general term for {heliostat}.
[1913 Webster]
from
The Collaborative International Dictionary of English v.0.48
Heliostat \He"li*o*stat\, n. [Helio- + Gr. ? placed, standing,
fr. ? to place, stand: cf. F. h['e]liostate.]
An instrument consisting of a mirror moved by clockwork, by
which a sunbeam is made apparently stationary, by being
steadily directed to one spot during the whole of its diurnal
period; also, a geodetic heliotrope.
[1913 Webster]