Islamic metalwork

V&A — Physical description

The astrolabe consists of a mater (casing), with an extension at the top (called the kursi in Arabic) that is of complex shape and structure and ends in a loop for a suspension cord; a rete (openwork star map); seven plates for different latitudes; an alidade (viewing device); and the pin and "horse" that hold the instrument together. The accuracy of the scientific data engraved on the astrolabe has not been assessed, and the following is based on the presumption that the main captions engraved on the plates are correct. Going by these, the northernmost latitude at which the astrolabe could be used was 40° N, which is approximately the latitude of Astrakhan (now Volgograd in Russia), and the sourthernmost, 29° N, which is the latitude for Shiraz in Iran. There is, as expected, a plate engraved for 37° N, which is the approximate latitude of Urmia, the residence of the man who commissioned the instrument and its place of manufacture by 'Abd al-Ghafur. One plate bears a tablet of horizons on one side, but all seven have been engraved on both sides, so that there are 13 plates for specific latitudes. The captions on the plates that give the latitude and the length of the longest day are engraved in a crescent-shaped area below the horizon line. There are two different formats, one with the text presented unframed, as though written over the plant-based ornament that forms the background (A), the other with the two texts in separate scalloped cartouches (B). In A, the wording is, "for latitude ...", and in B, "latitude". This suggests that the instrument is composite. This is supported by the presence of two plates engraves for 30°N. On the other hand, two plates are engraved in format A on one side, and in format B on the other. The plates are for the following latitudes: 1/1 format B 29° N 1/2 format B 30° N, with 30 represented by the abjad letter L 2/1 format A 30° N, with 30 represented by the abjad letter L plus an astronomical sign marking the absence of further letters. 3/1 format A 32° N 4/1 format B 33° N 5/1 format B 34° N 6/1 format A 35° N 5/2 format B 36° N 2/2 format A 37° N 6/2 format B 39° N 7/1 format B 40° N 7/2 format B 43° N 3/2 format B 46° N 4/2 tablet of horizons Tim Stanley