Astrolabe, by Khalil Muhammad and Abd al-A'imma, Persian, 1707/8

Parts

It comprises: a mater, a rete, 5 plates, an alidade, a horse and pin, 2 greenish cords ('ilaqas).

Throne

The throne is of the indo-persian, engraved type. It is attached with a integrated base. Ornate throne embossed with floral pattern and inscription of vaguely Moorish-arch shaped. On the back of the throne the name of the Shah Husain I (1642-1722) is engraved.

Ring

The ring is of the simple, round cross-section type (i.e. simple plain ring made from a round rod or piece of metal).

Shackle

Shackle of the omega type (i.e. Ω-shaped shackle). Engraved texture added to the outer edge of the shackle.

Mater

The mater and limb are of one-piece construction. The rim is marked with a degree scale 0-360° divided every 15 degrees, subdivided every 5 degrees, further divided every degree, and labelled in Abjad numerals every 5 degrees.

Womb

The womb is engraved as a gazeteer of the longitude, latitude, and inhiraf of 44 places.

Back

On the back are scales of degrees; cotangent scales; a sine and cosine graph; the arcs of the signs of the zodiac with graphs of the sun's meridian altitude for latitudes 28°-42° at intervals of 2°, and of azimuths of the Qibla for Shîrâz, Baghdad, Isfahan and oûs; a shadow-square within which is a table of triplicities; and an astrological table of the signs of the zodiac, the terms and faces of the planets and the 28 mansions of the moon.

Rete

The rete is of the foliate type. The east-west band is counter-changed. There is a single tab for rotation. There are numerous construction marks on the back of the rete, including ecliptic divisions. It features 22 stars.

Zodiac label

The ecliptic circle is divided and labelled in Abjad numerals every 3 degrees. The zodiac is labelled: حمل , ثور , جوزا , سرطان , اسد , سنبله , ميزان , عقرب , قوس , جدي , دلو , حوت.

Pin and horse

The rete is attached using a pin and horse. A simple, thick pin and an ornate horse hold the rete and tympans together. The horse is particularly well made.

Alidade

On the finely decorated alidade there is an inscription which bears the name of the owner and the year [1]119 [A.H.]. There are also scales of degrees and solar declinations.

Ilaqa

There is an ilaqa of blue silk and another of yellow silk.

Plates

There are 5 plates, for latitudes 22°, 34°; 30°, 35°; 38°, 43°; 29° and a tablet of horizons of eastern type. On one plate there are hour lines for Babylonian hours (horæ ab ortu solis) in addition to the usual lines for unequal (planetary) hours, and on another the unequal hour-lines are omitted and hour lines for Babylonian hours are drawn for every quarter of an hour