A Royal English Medieval Astrolabe Made for Use in Northern Italy

Abstract

This article describes a medieval English astrolabe usually known as Mensing-26 and now in the Adler Planetarium and Astronomical Museum in Chicago. Details of its star positions and names, saints feast days, metallurgy, construction, and general style (featuring a “quatrefoil” rete) are examined and used to place the instrument as one of a small group of astrolabes, epitomised by the great Sloane astrolabe, which has been associated with King Edward III. Using this hypothesis, potential original owners of the instrument in c. 1330–1340 are proposed. It is also shown how the astrolabe was later modified to have a second life as a working instrument in Renaissance Florence.