Astrolabe
AS'TROLABE, noun [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.