Astrolabe, by Ibrahim ibn Sharaf ad-din Husayn, Persian, 1641

The alidade is broken. The signature on the rim is much worn. Other inscriptions on the front of the kursi and along the rim.

Parts

It comprises: a mater, a rete, 4 plates, an alidade, a horse and pin.

Throne

The throne is of the indo-persian, engraved type and it is attached with a integrated base. This unusual shaped throne has trefoil decorations on both sides. The front and the back bear inscriptions.

Ring

The ring is missing.

Shackle

Shackle of the trefoil type.

Mater

The mater and limb are of one-piece construction. The tab that holds the plates in place is located at the bottom of the instrument, i.e., 180° from the throne. The rim is marked with a degree scale 0-360° divided every 5 degrees, subdivided every degree, and labelled in Abjad numerals every 5 degrees. The limb bears an inscription.

Womb

The womb is engraved with a gazeteer of the latitude, longitude and inhiraf of 46 towns.

Back

On the back are engraved a sine graph, the arcs of the signs of the zodiac and an unequal hour diagram, cotangent scales, a shadow-square, within which is an astrological table of limits, etc., and scales of degrees.There is an astrological table of limits.

Rete

The rete is of the foliate (single knob) type. The single rotational knob is made of copper. It features 26 stars.

Zodiac label

The zodiac on the rete is labelled: الحمل , الثور , الجوزا , السرطان , الاسد , السنبله , الميزان , العقرب , القوس , الجدي , الدلو , الحوت.

Pin and horse

The rete is attached using a pin and horse.

Alidade

Double-ended. The alidade has broken at the left sighting vane.

Plates

There are 4 plates, for latitudes 21°40', 38°; 29° 34°; 32°, 37°; including a plate engraved on one side as a tablet of horizons and on the other as a tablet of ecliptical co-ordinates. One of the plates is marked as a tablet of horizons on one side and as a tablet of ecliptical co-ordinates on the other.