sextant

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sextant Optical instrument for finding latitude (angular distance n or s of the Equator). A sextant consists of a frame with a curved scale marked in degrees, a movable arm with a mirror at the pivot, a half-silvered glass and a telescope. The instrument measures the angle of a heavenly body above the horizon, which depends on the observer's latitude. A set of tables gives the corresponding latitude for various angles measured.

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