Crafted from gilded brass in 1375, astrolabes such as this functioned as a two-dimensional way to measure the altitudes of the sun—or any fixed star. Invented by the Greeks and then perfected by Muslim astronomers in the medieval period, astrolabes could also be used to determine latitude, navigate on land and sea, chart horoscopes, and survey land.
The astrolabe shown here is one of the earliest European examples and bears a dated Latin inscription signed by its creator, which reads in English: “This astrolabe was crafted and tested, together with the rings, by Petrus Raimondus from the lineage of the kings of Aragon in A.D. 1375, in Barcelona. The latitude of Barcelona [being] 41 degrees, the longitude 39.”
This early example of an astrolabe can be seen at the Museum of Fine Arts in Boston.