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“siderostat”
A telescopic instrument used for reflecting a star's light in an unvarying direction: The main part of a siderostat is a plane mirror which is rotated by the mechanism of a time piece in order to compensate for the earth's rotation.
This entry is located in the following units:
sidero-, sider- (iron)
(page 3)
stato-, stat-, sta-, -static, -stasi, staso-, -stasis, -stasia, -stacy, -stitute, -stitution, -sist
(page 16)