QUADRANT

A copper alloy horary (unequal hour) quadrant of high medieval date. The quadrant is flat and wedge-shaped in plan with a curved bottom edge. The upper face is incised with lines and numbers to aid in the reading of time and also for measuring distances. The quadrant has several curved lines (arcs of circles) expanding from a central point in the centre (top). Dr. John Davis has kindly supplied the following information: "The numerals in the centre are 4-8-12-12-8-4 and are arranged along the edges of a shadow-square. The numbers around the periphery are [15], 30, 45, 60. 75, [90], although not all are easy to read. They indicate the height (altitude) of the sun in degrees and use the medieval form of the numerals.

The following information was written by Dr. John Davis of the British Sundial Society Bulletin and initially published in The Searcher Magazine (May 2015). It also appeared in the Society's Bulletin (June 2015) and further information and discussion can be found in these articles.
"...the engraved semi-circular line...indicates noon. The other part-circles with increasing radii show the successive hours either before or after noon: the user had to know which part of the day it was as the hours are symmetrical about noon and, in this case, they are not numbered. Note that all the hour lines pass through the origin of the quadrant. The same basic scheme of hour-lines is also commonly found on the backs of astrolabes. Astrolabes, though, were exceedingly expensive instruments and would only have been owned by the top levels of society. As a result, they were highly prized and several hundred of them have survived and are to be found in museums and other collections. Simple quadrants, more affordable but still expensive, might have been owned by scholars, wealthy merchants or senior churchmen, and were probably relatively common but are today almost unknown as they would not have been valued once they were superseded and the brass would have been recycled" (Davis 2015).

J. Davis: 'The Chetwode Quadrant - a medieval unequal-hour quadrant', British Sundial Society Bulletin, 27(ii), pp. 2-6 (June 2015).