AS'TROLABE, n. [Gr. a star, and to take.] 1. An instrument formerly used for taking the altitude of the sun or stars at sea.2. A stereographic projection of the sphere, either upon the plane of the equator, the eye being supposed to be in the pole of the world; or upon the plane of the meridian, the eye being in the point of intersection of the equinoctial and the horizon.3. Among the ancients, the same as the modern armillary sphere.
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