A Maghribi astrolabe, North Africa, circa 1800

Brass

Old repair to the rete, overall good condition, as viewed.
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This unsigned and undated Maghribi astrolabe, previously unrecorded, is typical of the standard astrolabes that were made in the Maghrib during the period up to the 19th century. The engraving is accurate and the calligraphy rather elegant. The instrument is probably from c. 1800.

The numbers are marked in alphanumerical notation according to the Maghribi convention.  The throne is raised and without decoration. The shackle and the suspensory apparatus are original.  The outer rim of the mater bears a 360° scale divided into 5°-intervals, subdivided into single degrees. The 5°-arguments are labelled thrice up to 100°, then up to 60°. The surface of the mater is carefully engraved with an extravagant foliate design.

The rete is typically Maghribi in style, with counter-changes along the horizontal bar and star-pointers of different, but all standard, design. The ecliptic scale is labelled with the names of the zodiacal signs and is divided into 6°-intervals. The following 5+5+6+6 = 22 stars are represented in each quadrant of the ecliptic beginning with the vernal equinox (on the left), each pointer bearing standard star-names, mainly in abbreviated form:
1^st quadrant: batn qaytûs - dabarân - ghûl - qadam al-jawzâ' - 'ayyûq
2^nd: 'abûr - ghumaysâ' - jahba (?) - al-dubb - al-ghurâb
3^rd: a'zal - râmih - fakka - 'unuq al-hayya - qalb al-'aqrab - ra's al-hawwâ'
4^th: wâqi' - al-tâ'ir - dulfîn - dhanab al-jady - mankib - dhanab qaytûs

There are three plates with astrolabic markings for the following latitudes and associated localities: 21°40' - Mecca; 30° - Cairo, Sijilmasa; 31°30' - Marrakesh; 33°30' - no localities mentioned; 34° - Meknes; 35° - Tangiers.  On each side, there are altitude circles for each 6° and azimuth circles for each 10, as well as curves for the seasonal hours below the horizon. On all plates, there are curves highlighted with fishbone markings representing the t.mes s of the two daylight prayers, the zuhr and the 'asr, whose t.mes s are defined in terms of shadow-lengths. On the second and third plates, there are highlighted curves at 18° below the horizon for the prayers at daybreak (fajr) and nightfall (shafaq). The orthography of the name Sijilmâsa - a city destroyed centuries before this astrolabe was made, and included only because of tradition - is curious: it is written as two words, sijil mâsa. The plate for Mecca is badly scratched.

There is another plate with unlabelled and incomplete markings for latitude 36° (not stated). Here the altitude circles are for each 5° and there are no azimuth circles.  On the back of one of these plates there is a set of universal markings of the kind associated with Ibn Bâso ca. 1300. These are for performing the operations of spherical astronomy for all latitudes. Such markings are common on Western Islamic astrolabes.

The back bears the usual scales found on late Maghribi astrolabes. On the upper outer rim, there are two altitude scales. Within these, there is a solar scale with each 30° marked with the names of the zodiac. Then within this there is a calendar scale with the months labelled in the Western Islamic (= European) convention, as follows (showing only consonants and long vowels):
ynyr - fbrâ'r - mârs - 'brîl - mâyh - yûnyh
yûlyh - 'gh-sh-t - sh-tnbr - 'ktûbr - nûnbr - djnbr
The equinox corresponds to March 14, by which one could date the piece to ca. 1300, but this should not be taken too seriously. (In late Islamic instrumentation, blind tradition prevailed.) Below the horizontal diameter, there is a double shadow-square, with each scale marked in digits (base 12), labelled for each 3 digits and subdivided for each 1 digit. The horizontal scale is labelled mabsût and the vertical ones mankûs, indicating that they display the cotangents and tangents, respectively, of the solar altitude.  The alidade is unmarked and, along with the pin and wedge, is original.

We are grateful to Professor David King for his assistance in cataloguing this lot.

Bibliography: For a survey of Maghribi astronomy and a list of Maghribi astronomical instruments see: King, David A., "On the History of Astronomy in the Medieval Maghrib", in Études Philosophiques et Sociologiques Dédiées à Jamal ed-Dine Alaoui, Fez, 1998, pp. 27-61.
Gunther, Robert T., The Astrolabes of the World ... , 2 vols., Oxford: The University Press, 1932, reprinted in 1 vol., London: The Holland Press, 1976.
Hartner, Willy, "The principle and use of the astrolabe", a chapter in Arthur Upham Pope, ed., A Survey of Persian Art from Prehistoric t.mes s to the Present, 9 vols., London & New York NY: Oxford University Press, 1938-39, reprinted without the original plates in Willy Hartner - Oriens-Occidens - Ausgewählte Schriften zur Wissenschafts- und Kulturgeschichte - Festschrift zum 60. Geburtstag, Hildesheim: Georg Olms, l968, I, pp. 287-3ll, and again with them in Astrolabica (Paris: Société Internationale de l'Astrolabe), 1 (1978).
King, David A., In Synchrony with the Heavens - Studies in Astronomical t.mes keeping and Instrumentation in Islamic Civilization, vol. 1: The Call of the Muezzin - Studies I-IX, and vol. 2: Instruments of Mass Calculation - Studies X-XVIII, (Islamic Philosophy, Theology and Science - Texts and Studies, vols. LV:1-2), Leiden & Boston: Brill, 2004-05.
King, David A., World-Maps for Finding the Direction and Distance to Mecca: Innovation and Tradition in Islamic Science, Leiden: Brill, & London: Al-Furqan, 1999.
Mayer, Leo A., Islamic Astrolabists and their Works, Geneva: Albert Kundig, 1956.
Price, Derek J. de Solla, et al., A Computerized Checklist of Astrolabes, New Haven, Conn.: Yale University, Department of the History of Science, 1973.