 He invented an observational instrument known as the torquetum, a mechanical device to transform between spherical coordinate systems.Several later Islamic authors were influenced by Jābir, including Ibn Rushd (Averroes) and Nur ad-Din al-Betrugi, both of whom worked in Andalusia.The work was transmitted to Egypt in the 12th century by Maimonides and further east by the end of the 13th century.