A quadrant is a handheld measuring device used by navigators to determine the altitude of celestial bodies above the horizon. It features a quarter-circle arc marked in degrees, a sighting mechanism and a plumb bob or mirror. Navigators use the resulting angle to calculate their latitude at sea.
Heard on the job
He shot the sun with the quadrant at noon to get our latitude.
Insider tip
While largely replaced by the sextant, early navigators relied on the quadrant for ocean crossings before the invention of precise chronometers.