Astrolabe, by Muhammad ibn Fattuh al-Khama'iri, Seville, 1221/2

A fine astrolabe of the maghrebi, North African style. Differently from the other object in the Museum's collection made by the same maker (HSM inv. 50934), this astrolabe does not have the silver knobs at the base of its stars, though the scales around the rim are notched, showing that the maker was experimenting with different ways of making the object usable at night, in poor light conditions.

Parts

It comprises: a mater, a rete, 5 platese, a horse and pin. The alidade is missing.

Throne

The throne is typical of Maghrebi astrolabes. It is attached with a integrated base. The front of the throne is undecorated. The back bears the maker's inscription.

Ring

The ring is of the simple, squared cross-section type.

Shackle

Shackle of the omega type (i.e. Ω-shaped shackle).

Mater

The mater and limb are of two pieces, soldered construction. 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 scale is notched every 15 degrees to facilitate the use in poor light.

Womb

The womb is marked with 10 concentric rings. The first four rings contain 2 scales of terms. The next ring contains a scale of triplicities, then a zodiacal calendar, another scale of triplicities, while the three innermost rings contain increments of fortune, decans, faces.

A central ring contains an inscription.

Back

The back is worn and parts are illegible. It contains 8 concentric scales: two altitude scales on the upper half of the rim 0-90° divideed and notched every 5 degrees, subdivided every degree and labelled in Abjad numerals every 5 degrees; a zodiacal calendar divided in 30 degrees labelled every 5 degrees on top of each sign; a Julian calendar with a scale of the days of the month, is divided every 5 days, subdivided every day, and labelled every 5 days plus the last day; a perpetual calendar for a 28-year cycle.

There is a shadow square in the central, lower half, both the the left and right sides are divided into 12 fingers vertical and 12 fingers horizontal, marked every 2. The lower half of the rim is marked with a shadow scale projection.

Rete

The rete is of the Maghrebi type with hook star pointers (4 of which are broken), some with inverted-heart bases, some with simple loops. It features 29 stars. Two knobs for rotation are missing.

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. The horse is a replacement.

Alidade

The alidade is missing.

Plates

There are 4 plates, for latitudes 30°, 31°, 33°, 34°, 36°, 37° and 41°. They are engraved with almucantars for every 3 degrees, azimuths for every 5 degrees, 12 unequal hours labelled in both Abjad numerals and words and 5 lines of Muslim prayers. They are marked المشرق (east) and المغرب (west). Some lines for Muslim prayers are roughly engraved on one of the plates.