Ptolemaeus Arabus et Latinus

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Work C.1.20

Muʾayyad al-Din al-ʿUrḍī
مقدّمة في تصحيح برهان الشكل الرابع من تاسعة المجسطي
Muqaddima fī taṣḥīḥ burhān al-shakl al-rābiʿ min tāsiʿat al-Majisṭī

This short note provides a correction (taṣḥīḥ) of the geometrical argument related to Figure 4 in Chapter IX.6 of Ptolemy’s Almagest. In most manuscripts the proof is provided with a diagram similar to that in the Almagest, but with the deferent and apsidal line added. For an abbreviated version, which probably goes back to Quṭb al-Dīn al-Shīrāzī or his circle, see C.1.29. Alternative title: Muqaddima nāfiʿ fī taṣḥīḥ burhān al-shakl al-rābiʿ min tāsiʿa bi-l-Majisṭī.

Text: [Istanbul, Nuruosmaniye, 2971]

[Incipit] (93v) ليكن الخطّ المارّ بالمراكز والأوج البطئ الحركة ا ب ج د وليكن ا مركز البروج وب مركز معدّل المسير وج مركز المدير. [Explicit] (94r) ولأنّ زاويتي ل م قائمتان ووتري ب د ب ه متساويان فمربّعا د ل ا ل مثل مربّعي ه م ا م لكنّ مربّعا د ل ه م متساويان فمربّعا ا م ا ل متساويان فخطّا ا ل ا م متساويان وزاويتا د ا ل ه ا م متساويان وذلك ما أردنا أن نبيّن.

Bibl.: GAS VIFuat Sezgin, Geschichte des arabischen Schrifttums. Vol. VI: Astronomie bis ca. 430 H., Leiden: Brill, 1978, pp. 94 (no. 31g) and 292 (Nachtrag zu S. 94); George Saliba, The Astronomical Work of Muʾayyad al-Dīn al-ʿUrdī. A Thirteenth Century Reform of Ptolemaic Astronomy. Kitāb al-Hay’ah. Edition and Introduction, Beirut: Center for Arab Unity Studies, 1990, p. 31.

Ed.: None.