An early English astrolabe at Gonville & Caius College,Cambridge,and Walter of Elveden’s Kalendarium

A small brass astrolabe belonging to Gonville & Caius College, Cambridge, has been studied. Referred to as “Caius B,” it is shown that it is almost certainly English and dates to the early fourteenth century, possibly c. 1326. It has not previously been studied in depth but has long been associated with the Cambridge scholar Walter of Elveden, the writer of a Kalendarium which was a predecessor of those by Nicholas of Lynn and John Somer. Strong evidence has been found to support this association, and to link the design and features of the astrolabe to church architecture of the time, particularly of Norwich Cathedral. The accuracy of the astrolabe layout has also been studied and some errors have been observed which shed light on the methods of drawing and the sources of astronomical data available to the maker.