In Renaissance Italian, quartiere (quarter) was synonymous with "quadrant." The reduction quadrant was generally engraved on nautical quadrants and astrolabes and provides graphic solutions to navigation problems. It is a square (also called nautical square or sinical quadrant) inscribed with a network of lines parallel to the sides and an arc divided into 90°. The instrument serves to reduce the computation of the trigonometric functions for an angle greater than 90° to the computation for an angle lying in the quadrant.