A rare Andalusian brass astrolabe Islamic Spain, 13th Century, probably before 1238

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Lot 116
A rare Andalusian brass astrolabe
Islamic Spain, 13th Century, probably before 1238

Sold for £ 82,500 (US$ 103,137) inc. premium
A rare Andalusian brass astrolabe
Islamic Spain, 13th Century, probably before 1238
of cast brass, hammered and engraved with three lobed throne with shackle and suspension loop, rete, five plates, engraved in western kufic, to edge of back in later cursive script, later horse and pin, possibly later alidade
12.7 cm. max.


  • Astrolabes were widely used in the Islamic world both for navigation and for finding the Qibla, or the direction of Mecca. They were also used to find the times of sunrise in order to help schedule morning prayers. During the Islamic period, numerous innovations were developed such as the addition of angular scales, adding circles indicating azimuths on the horizon. The present lot is a very rare example of an astrolabe which produced in Islamic Spain.

    The limb was separately cast from the back plate, probably in one piece with a throne, possibly separately. In the former case the throne was broken off and the present throne, which may be the original but is not certainly so, attached or re-attached by two rivets. This operation caused the limb to fracture and the section between 42° and 75° was dovetailed back in. At the same time the upper part of the back plate was crudely re-riveted to the limb, three of the rivets being proud of the surface and breaking the engraving. The limb carries a 360° scale numbered by groups of 5 (with 100s but without 200s and 300s) and subdivided to single degrees. There is considerable wear to the numerals in the section running from 55° to 180°. In the first quadrant only (0°-90°) the 5° division lines are continued from the face of the limb over the edge to join the 5° lines on the back, the top of the back plate in this quadrant being notched for single degrees. Although the other quadrants are plain, the 180° and 270° positions are marked by a similar notch running over the limb to join the graduations on the face and back plate.

    The three-lobed throne is relatively low and pierced with three holes of which the central, smaller, one may have been pierced later than the other two. It is worked in the middle of an equilateral triangle centred on the 0/360° line of the limb. The shackle is likely to be original, but lacks two washers allowing it to fit closely to the top of the throne.

    The unusual rete now consists only of the ecliptic circle and twelve star pointers within it. These have curved or hooked pointers arising from low bases each set with a silver point (two missing). The Capricorn indicator is a thin rectangle with central index line. There is no east-west bar running across the rete, rather a plain arc within the ecliptic circle springing from 0° Aries and 30° Virgo. Since there is no indication that this arc continued outside the ecliptic ring, the chamfered edge of which carries incised lines for the divisions of the signs which are undisturbed, the ecliptic was probably connected to the arc for the tropic of Capricorn by only three struts arising from Libra and Pisces and Gemini where there are the remains of old repair work. If this be the case, then we may postulate that it caused a structural weakness in the rete that led to breakage and the loss of all the part outside the ecliptic.
    The ecliptic circle is divided into 6 degrees and labelled with the names of the signs of the zodiac.

    The twelve stars on the rete are (in order of right ascension):
    β Andromedae qalb al-ḥūt قلب الحوت
    α Aurigae al-ʿayyūq العيّوق
    ι Ursae Maioris al-dubb الدبّ
    β Leonis al-ṣarfa صرفة
    α Bootis al-rāmiḥ الرامح
    α Serpentis --- al-ḥayya --- الحيّة
    α Lyrae al-wāqiʿ الواقع
    β Orionis al-jawzā' الجوزا
    α Aquilae al-ṭā'ir الطاير
    α Cygni al-ridf الردف
    ? ? ?
    β Pegasi mankib al-faras منكب الفرس

    Note: The penultimate star is placed at 19° Aquarius and so should be ε Pegasi (enif - أنف) although the reading is not clear.

    As noted above, the upper part of the back of the astrolabe became detached from the limb, no doubt at the same time as the throne was broken off, and was re-riveted. The outermost of the three nested scales on the back carries two 90° altitude scales numbered every 5° and subdivided to 1°. The double inner scale is a zodiac calendar divided to numbered 5° divisions. This zodiac calendar shares 1° subdivisions with the altitude scales. The innermost scale is for the Julian calendar (0° Aries = 15/14 March) divided to numbered 5 or 6° divisions and subdivided to 1°.
    At the centre is a double shadow square for base 12 with every 3 units numbered. The vertical double inscriptions at the centre read 'the vertical shadow' and 'the vertical'. The horizontal inscription reads 'the horizontal [shadow].
    Because the inscriptions on the back plate, written in the same small and neat Kufic script as was employed to number the face of the limb, had become so worn as to be almost unreadable, they were re-engraved at a later date in a heavy cursive script. At the same time the division lines for the scales were somewhat crudely renewed. The lower two quadrants of the outer degree scale seem not originally to have been numbered; the scribe who added numbers to them also added the redundant inscription 'the vertical' to the shadow square.

    Mater. This is plain but gilt as the rest of the instrument may once have been.

    Plates. There are five plates, all engraved on both faces and each with a lug at the top for fixing it in the mater. Each plate carries almucantars (lines of equal altitude) on both faces with 6° intervals numbered from 6 to 72° on both sides of the plates except for plate 2b which numbers to 78; plate 5a to 66; plate 5b to 60°. The plates are engraved for azimuths on both faces for every 10 degrees numbered 10 to 90°. All the plates also carry lines for the unequal hours below the horizon; each hour being numbered. Plates 2a, 2b and 4a have the names engraved below the horizon for east on the left and west on the right. Plate 1 has jagged damaged to a part of the circumference. The centre of each plate is inscribed with the latitude. These inscriptions read:

    1A for the latitude of Valencia 39° 30ʹ li-arḍ balansiyya 39 30 لعرض بلنسية لط ل
    1B for the latitude of Basra 33° li-arḍ Baṣra 33 لعرض البصرة لجـ
    2A for the latitude of Marrakesh 30° li-arḍ Marākush 30 لعرض مراكش ل
    2B for the latitude of Ceuta 35° li-arḍ Sabta 35 لعرض سبتة له
    3A for the latitude of Almeria 36° 30ʹ li-arḍ Almarīʿa 36 30 لعرض المريع لول
    3B for the latitude of Barca 32° li-arḍ Barqa 32 لعرض برقة لب
    4A for the latitude of Medina 25° li-arḍ Yathrib 25 لعرض يثرب كه
    4B for the latitude of Mecca 22° li-arḍ Makka 22 لعرض مكة كب
    5A for the latitude of Cairo 30° li-arḍ Qāhira 30 لعرض قاهرة ل
    5B for the latitude 37° 30ʹ li-arḍ 37 30 لعرض لز ل

    The latitude of 37° 30ʹ for which no place is indicated normally corresponds on early astrolabes with Seville, Malaga and Granada. This means that, Mecca and Medina being excluded as automatic inclusions in almost any astrolabe, three of the remaining eight places are found in Spain, four located in the northern Magreb and one (Barca) in Libya. Unlike the others, the latitudes of the Spanish cities are given to a precision of 30ʹ. Non-Spanish places are located with variable accuracy but all with values that can be paralleled on several other astrolabes from al-Andalus.

    Alidade, pin and horse. The alidade is likely to date from the restoration of the instrument. The pin and horse are modern.

    The presence of plates for three Spanish cities of which the latitudes are indicated to 30ʹ, unlike the other seven places, suggests that this astrolabe is to be located in al-Andalus. If this be so, then inclusion of a plate for Valencia suggests a date in the early 13th century CE, before the fall of this city to the crown of Aragon in 1238. This hypothesis finds some confirmation from the vernal equinox date of 15/14 March, which is compatible with this period. Unfortunately it is not conclusive and the reading is somewhat doubtful. The relatively low pierced lobed throne is consistent with astrolabes from Islamic Spain (see Gunther plates lxi, lxiii) or from the northern Maghreb (Gunther plate lxiv). Scope remains for further research on an instrument on which the damage it has suffered bears witness to the vicissitudes to which astrolabes may be subjected, while the repairs made to it testify to the esteem in which they were held.

    Robert T. Gunther, The Astrolabes of the World, 2 vols. Oxford 1932.
    David A. King, In Synchrony with the Heavens, Studies in astronomical Timekeeping and Instrumentation in medieval Islamic Civilization: ii, Instruments of mass Calculation, Leiden & Boston 2005.

    We are grateful for the assistance of Dr. Anthony Turner in cataloguing this lot.
A rare Andalusian brass astrolabe Islamic Spain, 13th Century, probably before 1238
A rare Andalusian brass astrolabe Islamic Spain, 13th Century, probably before 1238
A rare Andalusian brass astrolabe Islamic Spain, 13th Century, probably before 1238
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