English: The astrolabe, an invention of Hellenistic Alexandria, was the principal Islamic instrument for telling the time, surveying and determining latitude. By the later 9th century it was used throughout the Islamic world from Spain to India and later reached Christian Europe. By modelling the apparent rotation of the stars about the celestial pole, it solves a number of astronomical, and astrological, problems. ... See full description on web site. This astrolabe is superbly engraved with a mass of technical information, Qur’anic verses and Persian poetry. The latter includes a chronogram, ‘It is Alexander’s mirror and the cup in which one can see the world’, giving the date 1060 AH (1650 AD). Muhammad Mahdi, who worked between 1649 and 1663, came of a family of astrolabists and was responsible for the instrument’s calibration, the most important stage of its manufacture. He provided the astrolabe with plates for five different latitudes with gazetteers of their principal cities.