Muhammad ibn Abi'l Qasim ibn Bakran (12th century)
Astrolabe, 1102-1103 (496 A.H.)
Florence, Istituto e Museo di Storia della Scienza, inv. 1105

This small astrolabe, possibly of Persian origin, has four tympanums engraved on both faces for different latitudes. On the back, a moving arm fitted with sights allowed the user to measure a star's altitude.