AN IMPORTANT MAMLUK EGYPTIAN ASTROLABE MATER AND PLATES DATED A.H. 693/A.D. 1293/94 WITH A REPLACEMENT OTTOMAN TURKISH RETE DATED A.H. 1087/A.D. 1676/77 AND AN ADDITIONAL PLATE

Brass with some silver inlay on the scale around the front of the mater

In overall fairly good condition, with some oxidization and minor patination on surface, as viewed.
"In response to your inquiry, we are pleased to provide you with a general report of the condition of the property described above. Since we are not professional conservators or restorers, we urge you to consult with a restorer or conservator of your choice who will be better able to provide a detailed, professional report. Prospective buyers should inspect each lot to satisfy themselves as to condition and must understand that any statement made by Sotheby's is merely a subjective, qualified opinion. Prospective buyers should also refer to any Important Notices regarding this sale, which are printed in the Sale Catalogue.
NOTWITHSTANDING THIS REPORT OR ANY DISCUSSIONS CONCERNING A LOT, ALL LOTS ARE OFFERED AND SOLD AS IS" IN ACCORDANCE WITH THE CONDITIONS OF BUSINESS PRINTED IN THE SALE CATALOGUE."

This composite astrolabe is an object of singular historical interest. It was presumably missing its rete when it came into the hands of the Ottoman craftsman who fitted it with a new rete and an additional plate for his own latitudes. Fortunately he did not dispose of one of the original plates, for these enable us to pinpoint the location of the original maker. The latitudes served are: 21º, 24º, 27º, 30º and 33º, which at first show only that they were intended for each 3º of latitude. However, the first two are for Mecca and Medina, the third is for Qulzum on the Red Sea coast and the last two would serve Cairo and Damascus. All of these localities belonged to the Mamluk domains, and we can be fairly certain that this was an astrolabe made in Egypt, if only because there is no plate for 36º to serve Aleppo.

There was considerable interest in astronomy and instrumentation in Mamluk Egypt and Syria, and Mamluk astronomers excelled in their field, particularly in the compilation of tables for astronomical timekeeping and in the design and construction of instruments. Close to two dozen Egyptian, Syrian and Yemeni astrolabes from the 13th and 14th centuries survive. This one is extremely competently made but only the original rete would give us an idea of its original artistic sophistication, which was surely remarkable.

the mamluk astrolabe components

The engraving is an elegant Kufic. The front and back of the throne is each decorated with an elaborate tangle of vegetal fronds, each symmetrical with respect to the vertical through the shackle and ring at the top. No related designs on astrolabe thrones can be adduced for comparison.

The scale on the rim of the mater is divided and labelled for each 5º up to 360º, subdivided for each 1º. Traces of silver inlay are found on some of the numbers, which, as elsewhere on the back, mater and plates on the instrument, are in the standard Arabic alphanumerical notation (abjad).

The mater is engraved with a set of half-horizons arranged in four quadrants for latitudes:

12        16        20        26        32        37        41        45        49        65

13        17        22        28        34        38        42        46        50

14        18        23        29        35        39        43        47        55

15        19        25        31        36        40        44        48        60

On each of the four axis, the declination scales are divided and labelled on either side of the celestial equator for each 6º up to 24º, subdivided for each 1º.

Below these markings is the date 693 (Hijra), which corresponds to 1293/94.

The three original plates are organised as follows, with latitudes ('ard) and lengths of longest daylight (sa'atuhu):

1a        21º       [Mecca]           13h 18m

1b        24º       [Medina]         13h 31m

2a        27º       [Qulzum]         13h 44m

3a        30º       [Cairo]             13h 58m

3b        33º       [Damascus]     14h 13m

The lengths of daylight are all accurately computed for a value of the obliquity of the ecliptic of the long-outdated value of Ptolemy of Alexandria (c.125), namely 23º 51' (this slavish adherence to tradition is typical of Islamic instrumentation; it means that the astrolabists had at their disposal some early Islamic table which ignored the new values of the obliquity derived by Muslim astronomers in the 9th century (23º 33' and 23º 35'). The values of longest daylight for these parameters would differ only by a minute or two from the ones given on these plates). On each plate there are altitude circles for each 3º and azimuth circles for each 10º, as well as curves below the horizon for the seasonal hours.

Plate 2b bears a complete set of universal markings known as the shakkaziyya. These result from an astrolabic projection in the plane of the solstitial colure (the great circle through the solstices perpendicular to the celestial equator) and are to be used with a graduated alidade for the solution of certain problems of spherical astronomy for any latitude. The shakkaziyya was first devised by Ibn al-Zarqalluh (Azarquiel) in al-Andalus in the 11th century and it was transmitted to Mamluk Syria and Egypt (and to medieval Europe). Its incorporation on Mamluk astrolabes is rare but not exceptional.

It is rather surprising that the back of the mater is engraved only with four sets of altitude scales around the rim. The horizontal and vertical diameters and the two concentric circles may be original, although to what end the latter were intended is unclear. It is completely against the tradition of medieval astrolabes that no further markings were engraved. The alidade appears too simple for it to be the original.

the ottoman additional components

These are distinguished by the use of a tidy naskhi typical of Ottoman astrolabes.

The rete is simple and in the Ottoman tradition with a horizontal bar counter-changed twice on each side and the supports of the lower equatorial bar extended to the ecliptic. The shapes of the star-pointers vary between a sabre and a hook. The names of the 6+6+5+6=23 stars in the four quadrants around the ecliptic are as follows:

dhabab qaytas [sic for qaytus] / al-ghul / 'ayn al-thawr / rijl al-jawza' / al-'ayyuq / mankib al-jawza' / shira yamaniya / shira al-sha'miya / al-dubb / rijl al-dubb / shuja' / fam al-ka's / simak al-a 'zal / al-ramih / 'unuq al-hayya / al-fakka / ra's al-hawwa' / al-waqi' / al-ta'ir / al-dadan [sic for al-ridf] / fam al-faras / mankib al-faras / dhanab qaytas [sic] shamali

The additional plate bears astrolabic markings on each side, as follows:

4a        41º       [Istanbul]         15h

4b        42º       [Edirne]           15h 2m

The altitude circles for each 3 are labelled only up to 9º, and the altitude circles for each 10º are not labelled. The lengths of longest daylight are not precise.

On the back a double shadow square has been inserted within the inner circle (which may also be an addition). Both sets of scales are for base 12 and those on the right are correctly labelled 'horizontal shadow or cotangent' (al-zill al-mabsut) and vertical shadow or tangent' (al-zill al-mankus). On the left these labels have been inappropriately switched. Below these squares is engraved '(in) the year 1087 (Hijra)', which corresponds to A.D. 1676/77.

It is possible that the person who added these items to the original mater and plates was the Istanbul craftsmen Ibrahim ibn Muhammad al-Balawi. He made replacement parts for a 13th-century Iraqi mater and plates, as well as two astrolabes of his own, both with Maghribi retes, all of his additions having been made between 1097 and 1099 Hijra. The style of his work resembles the additional parts on the present piece. His vocation in life – unique in the history of Muslim instrumentation – seems to have been making substitute parts for incomplete astrolabe components that were well worth saving.

We are grateful to Professor David King for his assistance in preparing the catalogue entry for this lot.

bibliographical notes

On Mamluk astronomy see King, "The Astronomy of the Mamluks", now supplemented by Charette, Mathematical Instrumentation in 14th-Century Egypt and Syria. On the shakkaziyya plate see the article "Shakkaziyya" in Enc. Islam, 2nd Edn. For an ordered list of Mamluk astrolabes see King, In Synchrony with the Heavens, II, pp.1009-1010. For an ordered list of Ottoman astrolabes see ibid., II, pp.1013-1014. On the geography of astrolabes – that is, the interpretation of latitudes and longest daylight on astrolabe plates – see ibid., II, pp.915-962. Al-Balawi is not listed in Mayer, Islamic Astrolabists.