- Navigational instrument - Navigator's aid measuring the angular distance between two visible objects - The sixth part of a circle. - An instrument for measuring angular distances between
objects, -- used esp. at sea, for ascertaining the latitude and
longitude. It is constructed on the same optical principle as Hadley's
quadrant, but usually of metal, with a nicer graduation, telescopic
sight, and its arc the sixth, and sometimes the third, part of a
circle. See Quadrant. - The constellation Sextans.