Inventory no. 52332 - Former Display Label
Persian ASTROLABE TEMPLATE (dastûr)
?18th century
Not signed or dated. Dimensions of board: 225 x 235 x 20 mm. Dimensions of brass astrolabe blank: diameter 74 mm., thickness 4.5 mm. The inscription at the top reads: 'Circle of the template (dastûr) of the limb of the astrolabe'.
The instrument consists of two walnut boards nailed together, the upper board having had cut from it an aperture to hold the mater of an astrolabe. On top is a sheet of varnished paper bearing scales marked in ink. The outer scale is a circle of 360° divided to each degree and numbered clockwise in abjad 0-5-10-5-20 ... 360; within the degree divisions in the upper semi-circle a second series of abjad numerals runs 5-10-15-20-25 ... 90-90-85-80 ... 5. Within the lower semi-circle are two cotangent scales corresponding to the divisions of the shadow-square across the lower two quadrants.
The dastûr is a protractor or, as in this example, a board used by a craftsman as a template to simplify inscribing the scales on an astrolabe. The brass blank is placed in the recess, and a straight edge placed over its centre connecting corresponding degree markings on the circular scale. The degree positions can then be engraved on the limb of the astrolabe. This procedure avoids geometrically marking each instrument individually, a simple copying process greatly speeding production. Another type of dastûr, in the form of a bowl with a graduated limb, in the centre of which the astrolabe was held by mastic, was seen by Sir John Chardin when in 1674 he visited in Isfahan the astrolabists Hasan {ain}Alî and Muhammad Amin b. Muhammad oâhir. The astrolabe template is an important technological development.
The four items shown here with the template, and the large wooden Islamic quadrant on the floor of the quadrant case, were associated with the template when it was brought to Europe from Iran, and may have formed part of an astrolabist's equipment.
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