From: Thomas Hockey et al. (eds.). The Biographical Encyclopedia of Astronomers, Springer Reference. New York: Springer, 2007, pp. 561-562
Ibn al‐Majdī: Shihāb al‐Dīn Abū al‐ʿAbbās Aḥmad ibn Rajab ibn Ṭaybughā al‐Majdī al‐Shāfiʿī
Born Cairo (Egypt), August 1366
Died Cairo (Egypt), 27/28 January 1447
Ibn al‐Majdī was one of the major Egyptian astronomers during the first half of the 15th century. He occupied the positions of muwaqqit (timekeeper) at al‐Azhar Mosque and of “head of the teachers” at the Jānibakiyya madrasa (privately endowed religious college).
Ibn al‐Majdī received a traditional religious education in the fields of Quranic studies, the prophetic traditions (ḥadīth), jurisprudence (fiqh), and Arabic grammar and philology. He also became an expert in arithmetic, geometry, the algebra of inheritance, theoretical astronomy (hayʾa), and applied astronomy (mīqāt, literally, the science of timekeeping). He learned the latter discipline under Jamāl al‐Dīn al‐Māridīnī, who had been a student of the celebrated astronomer of Damascus, Ibn al‐Shāṭir. Later, Ibn al‐Majdī himself became a highly regarded teacher in most of the above‐mentioned traditional disciplines as well as in the mathematical sciences. Virtually all of his younger contemporaries and immediate successors who were active in astronomy in Cairo were his pupils at one time or another. A prolific and competent writer, Ibn al‐Majdī played an important role as a didactic author; his writings were still read and commented upon in Egypt in the late 19th century.
Ibn al‐Majdī's numerous astronomical treatises deal with a wide range of topics. Several of them are devoted to the compilation of annual ephemerides but have yet to be carefully studied, notably his important treatise Jāmiʿ al‐mufīd fī bayān uṣūl al‐taqwīm wa‐ʾl‐mawālīd (which also deals with arithmetic, chronology, and astrology) and his Ghunyat al‐fahīm wa‐ʾl‐ṭarīq ilā ḥall al‐taqwīm. However, his important set of auxiliary tables for facilitating the calculation of planetary positions, entitled al‐Durr al‐yatīm fī tashīl ṣināʿat al‐taqwīm, has been investigated by E. S. Kennedy and D. King. These tables contain numerical entries for the Sun, Moon, and planets and make a clever use of periodic relations very similar to those that are at the core of Babylonian astronomy combined with an intelligent application of the methods and parameters of Ptolemaic zījes (astronomical handbooks). An anonymous set of such auxiliary tables based on the same principle is known from 11th‐century Iran, so we are witnessing an older tradition that reappeared in Cairo, circa 1400. Ibn al‐Majdī's auxiliary tables, supplemented by his contemporaries and successors, were extremely popular in Egypt up to the 19th century and inspired other, more extensive sets of tables based on the same methods and on the newer parameters of the zīj of Ulugh Beg.
Ibn al‐Majdī's activities dealt intensively with astronomical instruments. He composed numerous works, often didactical in character, dealing with the astrolabe, the theory of stereographic projection, the use of the standard astrolabic and sine quadrants as well as several unusual varieties of quadrants (most of which had been invented by his 14th‐century predecessors), and works on sundial theory. Among his writings we also find treatises on the determination of the lunar crescent visibility, a topic of prime importance to Muslim religious practice since the Islamic calendar is lunar. Ibn al‐Majdī also dealt with the applied problems of finding the qibla (the holy direction toward Mecca) and the orientation of roof ventilators.
Ibn al‐Majdī's contributions to arithmetic and algebra deserve further investigation. His treatise on sexagesimal arithmetic, a topic of fundamental importance for astronomers, was praised by his former pupil Sibṭ al‐Māridīnī as being the only satisfactory treatment of the subject known to him.
As a rule, astronomers during the Mamluk period in Egypt and Syria (1250–1517) did not engage in astrology because of their associations with religious institutions — either as muwaqqits in mosques or as teachers in madrasas or Sufi convents. Ibn al‐Majdī was something of an exception: A noted religious scholar, he nevertheless treated the topic of mathematical astrology in his al‐Jāmiʿ al‐mufīd and even cast a horoscope for a Mamluk amīr.
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King, David A. (1974). “A Double‐Argument Table for the Lunar Equation Attributed to Ibn Yūnus.” Centaurus 18: 129–146, esp. 131, 133, 141–142. (Reprinted in King, Islamic Mathematical Astronomy, V. London: Variorum Reprints, 1986; 2nd rev. ed., Aldershot: Variorum, 1993.)
——— (1986). A Survey of the Scientific Manuscripts in the Egyptian National Library. Winona Lake, Indiana: Eisenbrauns, no. C62.
King David, A. and E. S. Kennedy (1980). “Ibn al‐Majdī's Tables for Calculating Ephemerides.” Journal for the History of Arabic Science 4: 48–68. (Reprinted in King, Islamic Mathematical Astronomy, VI. London: Variorum Reprints, 1986; 2nd rev. ed., Aldershot: Variorum, 1993.)
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