Abu Rayhan Biruni (or: al-Biruni) (born in Uzbekistan, 973; died in Afghanistan, 1048) was one of the most prolific scientists of the Islamic Middle Ages. He authored more than 110 works of which 26 are still extant and 24 have been published in some form. This dissertation is about the remaining two works, which exist only in Arabic manuscripts and are hitherto unknown. We have reconstructed these two works on the basis of the Arabic manuscripts and translated the most important of the two into English.
The two works deal with the astrolabe, a medieval astronomical precision instrument that is mathematically and also artistically interesting. The astrolabe can be used as a compass and also as a clock. The first text is a handbook on the standard applications of the astrolabe.
The second text, which has been preserved in only one Arabic manuscript, deals with variants of the astrolabe which were made at courts, as "gadgets". This text shows the high level of the exact sciences in the Eastern Islamic world in the eleventh century.