Collection M.D., années 1960

Puis par descendance

This quadrant is a fascinating example of Morocco’s important scientific tradition in the manufacture of astronomical instruments, active from the tenth century and continuing until the end of the nineteenth century. The inscription on one of its faces identifies its patron, as well as the astronomers responsible. The reverse bears a scale of degrees and a diagram for sines and cosines (rabiʿ al-dastur). Two other quadrants, also produced in Jumada I 1219 by ʿAbdullah Aḥmad b. ʿAlī Marsil, are known: one in the History of Science Museum, Oxford (inv. 1956-127), and a second sold in London, Plakas Auctions, 16 December 2025, lot 176.

This quadrant, which represents a quarter of an astrolabe, is used to measure the altitude of celestial bodies above the horizon. This angular measurement then allows the calculation of various data such as latitude and time of day. The instrument also enables trigonometric calculations, thereby predicting the future positions of celestial objects. This type of quadrant also allows the computation of prayer times.

According to the lengthy engraved inscription on the quadrant, it was made in Rabat in 1219 AH for a certain Muḥammad, a jurist and scribe, son of Sidi ʿAbd al-Salām of Salé. The astrolabe is said to have been made by Sidi ʿAbdullah Aḥmad b. ʿAlī Marsil al-Andalusī, who is known to have been overseer of the Great Mosque of Rabat, while his father, ʿAlī Marsil al-Andalusī, was timekeeper of the al-Sunna Mosque, also in Rabat. The inscription also names al-Muʿṭī b. al-Ṭayyib al-Marīnī, timekeeper to Sultan Muḥammad III al-ʿAlawī (r. 1757–90) and his successor Mawlāy Sulaymān (r. 1792–1822), who is said to have supervised its production (see Muṣṭafā Mukhtār, Arabic text, Ashaʿm ḥāḍirat al-Ribāṭ fī al-ʿulūm al-kawniyya [The contribution of the city of Rabat to cosmic sciences], https://www.arrabita.ma/, 8 April 2026). Another engraved inscription indicates that the quadrant was calibrated for the latitude of Meknes.

The two other examples of this quadrant mentioned above are smaller in size: 14.7 cm (Oxford, inv. 1956-127) and 13.5 cm (Plakas Auctions), whereas the present example measures 18 cm. The dedication and signature on the quadrants appear identical, with the exception of the date, which is given on the two smaller examples in Western Arabic numerals typical of Moroccan usage, whereas here it is unusually rendered in Eastern Arabic numerals. It is possible that this date was added later by someone other than the maker.

Inscription (translated from Arabic):

Praise be to God, and prayers upon our master Muhammad and his family. This quadrant was made for the learned scribe Sayyid Muhammad b. al-Muqaddas al-Ibn (?) Sayyid al-Hajj ‘Abd al-Salam al-Salawiyyin (i.e. from Salé), in Rabat al-Fath, ‘Abdullah Ahmad b. ‘Ali Marsil al-Andalusi, made it under the guidance of the learned scholar al-Mu'ti ibn al-Tayyib Marin al-Nasab, in the text of Jumada I, 1219 H.

الحمدلله والصلة على سيدنا محمد واله مشالله صنع للفقيه الكاتب الأربع السيد محمد بن المقدس الإبن السيد الحاج عبد السلام السلاوين برباط الفتح صنعه عبدالله أحمد بن علي مرسيلي الأندلسي بإرشاد الفقيه المعدلي السيد المعطي بن الطيب مرين النسب في متن جمادى الأول سنة ١٢١٩