Astrolabic quadrant, made by Muhammad ibn Ahmad al-Mizzi

From Damascus, Syria, AD 1333-34

The time-keeper of the Great Mosque of Damascus

This instrument is signed by Muhammad ibn Ahmad al-Mizzi, the muwaqqit (official time-keeper) of the Great Umayyad Mosque of Damascus. The muwaqqit is responsible for determining the correct times for Muslim prayer, which must be carried out five times a day at specific intervals. There are four other astrolabic quadrants signed by the same craftsman, and they are the earliest known examples of this type of quadrant.

The astrolabic quadrant was probably designed in the eleventh or twelfth century. The instrument combines geometry and trigonometry to resolve problems of spherical astronomy. The engravings on the front reduce to a quarter-circle the essential information engraved on the front of the astrolabe. A thread with a moveable bead is attached to a hole at the centre. On the back is a trigonometric grid, mapped like modern graph-paper. Similar grids are also found at the back of astrolabes. The astrolabic quadrant is designed for use at one latitude only, and this instrument was made for the latitude of Damascus: 31°30'.

D. King, 'Rub'' in The encyclopedia of Islam, vol. 8 (, 1995), pp. 574-75

C.B.F. Walker, Astronomy before the telescope (London, The British Museum Press, 1996)

F. Maddison and E. Savage-Smith, Science, tools and magic: the, vol. 12 (London, Nour Foundation, 1997)