Quadrans Vetus

File:Quadrans Vetus inv 662 IF 22256.jpg]]

The Quadrans Vetus is a medieval astronomical instrument.

Known as the quadrans vetus ["old quadrant"], the three surviving medieval examples are in the Museo Galileo in Florence,{{cite web|title=Quadrans vetus|url=http://catalogue.museogalileo.it/object/QuadransVetus.html|publisher=Museo Galileo|access-date=29 October 2016}} the Museum of the History of Science in Oxford,{{cite web|title=Quadrans Vetus Horary Quadrant, French?, c. 1300|url=http://www.mhs.ox.ac.uk/object/inv/52020|publisher=Museum of the History of Science, Oxford|access-date=15 November 2019}} and the British Museum in London.{{cite web|title=sundial / horary quadrant / altitude dial|url=https://research.britishmuseum.org/research/collection_online/collection_object_details.aspx?assetId=111451001&objectId=55092&partId=1|publisher=British Museum|access-date=15 November 2019}}

There are two sights on one of the straight sides. The front carries the shadow square, the hour lines, and a mobile zodiacal cursor in its guide, to be positioned for the desired latitude. The back is inscribed with the zodiacal calendar. The instrument displays Gothic characters. Designed to measure heights, distances, and depths, the instrument could also be used as a universal dial. A similar quadrant is documented in a drawing by Antonio da Sangallo the Younger (c. 1520?) at the Gabinetto dei Disegni e delle Stampe (Department of Drawings and Prints) of the Uffizi.