A Maghribi astrolabe, unsigned, datable to the 18th or early 19th century,
Brass -- Diameter: 11cm. (4 5/16in.); Thickness: 0.4cm. ( 1/8in.)
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 but the calligraphy rather inelegant. The instrument is probably from the 18th or early 19th century.
The numbers are marked in alphanumerical notation according to the Maghribi convention.
The throne is unusual and elegantly cut at the edges, resembling a wide jester's hat. 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 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 6+5+6+6 = 23 stars are represented in each quadrant of the ecliptic beginning with the vernal equinox (on the left), each pointer bearing standard star-names:
1st quadrant: batn qaytu/ûs - al-dabarân - (al-)ghûl - qadam al-jawzâ' - (al-)'ayyûq - yad al-jawzâ'
2nd: (al-shi'râ al-)'abûr - (al-shi'râ al-)ghumaysâ' - shujâ' - rijl al-dubb - janâh al-ghurâb
3rd: (al-simâk al-)a'zal - (al-simâk al-)râmih - (al-munîr min al-)fakka - 'unuq al-hayya - qalb al-'aqrab - ra's (al-)hawwâ'
4th: (al-nasr al-)wâqi' - (al-nasr) al-tâ'ir - al-dulfnn - dhanab al-jady - (al-)ridf - mankib (al-faras)
There are three plates with astrolabic markings for the following latitudes and associated localities:
1a: 21° - Mecca1b: 30° - Cairo, Sijilmasa
2a: 31°30' - Marrakesh2b: 33° - Salé, Tripoli (Libya)
3a: 34° - Meknes, Fez3b: 36° - 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 times of the two daylight prayers, the zuhr and the 'asr, whose times 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 circles at 18° above the horizon are highlighted (they can be used for twilight determinations) and, for reasons unclear, the altitude circles corresponding to 30° as well.
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 12, 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 4 digits and subdivided for each 2 digits. 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.