Quadrant

[L. quadrans, a fourth part.] An instrument used in astronomy, navigation, sur¬ veying, and gunnery, for measuring altitudes and determining angular measurements. It gene¬ rally consists of a bra limb, the quarter of the circumference of a circle, mounted 011 a frame and marked with degrees, minutes, etc., and having a plumb-line or spirit-level for fixing the vertical or horizontal direction.