This large brass instrument (Image 1), probably made in the 14th century, is typical of medieval English astrolabes. It has been engraved for the latitude 52 degrees. This is the latitude of London, so it is reasonable to suppose that it was intended for use in the capital.
The rete, a cut-out plate with pointers showing the position of stars, rotates over the projection. Most of the 41 pointers here are labelled with the names of stars, many of them in Arabic, reflecting the Arab influences on medieval European astronomy. One is in the shape of a bird but is not labelled - it is probably marking the beak of the constellation Corvus (the crow).
