From: Thomas Hockey et al. (eds.). The Biographical Encyclopedia of Astronomers, Springer Reference. New York: Springer, 2007, pp. 577-578
Isfizārī: Abū Ḥātim al‐Muẓaffar ibn Ismāʿīl al‐Isfizārī
Flourished Khurāsān, (Iran), late 11th/early 12th century
Isfizārī, a contemporary of ʿUmar Khayyām and ʿAbd al‐Raḥmān al‐Khāzinī, constructed an accurate balance, composed books on mathematics and meteorology, and was inclined to the sciences of astronomy (hayʾa) and mechanics. Few details of his biography are known. The historian Ibn al‐Athīr and the astronomer Quṭb al‐Dīn al‐Shīrāzī link him to the observatory in Iṣfahān sponsored by the Saljūq king Malik‐Shāh (reigned: 10721092). Niẓāmī‐i ʿArūḍī reports that he met with Isfizārī in Balkh (in present‐day Afghanistan) in 1112 or 1113 in the company of Khayyām. Finally, Khāzinī writes, in 11211122, that he was already deceased. The most significant extant writing of Isfizārī is his treatise Irshād dhawī al‐ʿirfān ilā ṣināʿat al‐qaffān (Guiding the learned men in the art of the steelyard), a two‐part text on the theory and the practice of the steelyard balance. Three other texts constitute the rest of his scientific oeuvre: a summary of the so‐called 14th book of Euclid's Elements, a text on geometrical measurements, and a treatise on meteorology in Persian.
No work of astronomy by Isfizārī has reached us. However, he was one of the astronomers of Malik‐Shāh Observatory in Iṣfahān, although we do not know the exact date he joined the observatory or how long he stayed there. This observatory was one of the most important institutions of its kind in the 11th‐century Islamic world. Its program of astronomical research was active for about 20 years, from 10741075 until 1092, terminating with the death of both Malik‐Shāh and his influential minister Niẓām al‐Mulk. According to Quṭb al‐Dīn al‐Shīrāzī, there were eight men on the staff of the observatory, which included Isfizārī, ʿUmar Khayyām, Maymūn ibn Najīb al‐Wāsiṭī, Muḥammad ibn Aḥmad al‐Maʿmūrī, and Abū al‐ʿAbbās al‐Lawkarī.
The collective work done at the Malik‐Shāh Observatory was directed principally toward the reform of the solar calendar then in use in Iran. The result was the Jalālī calendar, which was one of the most accurate calendars ever devised. (For more information on this calendar, see the entry on Khayyām.)
Abattouy, Mohammed (2001). Greek Mechanics in Arabic Context: Thābit ibn Qurra, al‐Isfizārī and the Arabic Traditions of Aristotelian and Euclidean Mechanics. Science in Context 14: 179247.
al‐Bayhaqī, ʿAlī ibn Zayd (1988). Tārīkh ḥukamāʾ al‐islām, edited by M. Kurd ʿAlī. Damascus. (Contains a paragraph on al‐Isfizārī.)
al‐Isfizārī, Abū Ḥātim al‐Muẓaffar ibn Ismāʿīl (1977). Risālah‐i āthār‐iʿulwī. Tehran. (On his meteorological treatise.)
Sayılı, Aydın (1960). The Observatory in Islam. Ankara: Turkish Historical Society.
Youschkevitch, A. and B. A. Rosenfeld (1973). Al‐Khayyāmī. In Dictionary of Scientific Biography, edited by Charles Coulston Gillispie, Vol. 7, pp. 323334. New York: Charles Scribner's Sons.