| From: Thomas Hockey et al. (eds.). The Biographical Encyclopedia of Astronomers, Springer Reference. New York: Springer, 2007, pp. 567-568 |
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Courtesy of 
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Ibn al‐Ṣalāḥ: Najm al‐Dīn Abū al‐Futūḥ Aḥmad ibn Muḥammad ibn al‐Sarī ibn al‐Ṣalāḥ
Paul Kunitzsch
Born Sumaysāṭ
(Samsat, Turkey) or Hamadan (Iran)
Died Damascus (Syria),
1154
Ibn
al‐Ṣalāḥ was famous
for his acute understanding and critique of several Greek scientific texts
that had been translated and were circulating in Arabic. By profession, Ibn
al‐Ṣalāḥ
was a doctor. After studying and beginning his career in Baghdad, he is said
to have been appointed court‐physician in Mārdīn at the court
of the local ruler. He later settled in Damascus, where he died.
Especially of astronomical interest is his critique of the transmission
of the coordinates in Ptolemy's
star catalog (Almagest VII.5–VIII.1, dating from circa 150).
He knew and used five different translations of the Almagest: one in
Syriac and four in Arabic. For 88 of Ptolemy's 1,025 stars, Ibn al‐Ṣalāḥ notes the mistakes in the transmitted coordinates and proposes, for
most of them, better values found by him by observation and by comparison
with the celestial globe. Another text relevant for astronomy is his Treatise
on Projection. Projection here refers to the projection of the surface
of the sphere on to a plane, a procedure that was of fundamental importance
for the development and the construction of the astrolabe; Ptolemy's text
on this topic, the Planisphaerium, had also been translated into Arabic.
Other critical works of Ibn al‐Ṣalāḥ deal with mathematical and philosophical problems. But most of his
writings are still unpublished and unstudied.
Selected References
Ibn
al‐Ṣalāḥ
(1975). Zur Kritik der Koordinatenüberlieferung im Sternkatalog des Almagest, edited by Paul Kunitzsch. Göttingen: Vandenhoeck und Ruprecht. (Text, translation, and study.)
Lorch, Richard
(2000). “Ibn al‐Ṣalāḥ's
Treatise on Projection: A Preliminary Survey.” In Sic itur
ad astra: Studien zur Geschichte der Mathematik und
Naturwissenschaften. Festschrift für
den Arabisten Paul Kunitzsch
zum 70. Geburtstag,
edited by Menso Folkerts
and Richard Lorch, pp. 401–408. Wiesbaden: Harrassowitz Verlag.