An Arabic version of a treatise on the meteoroscope which is attributed to Theon of Alexandria in the two surviving manuscripts (cf. C.5). In MS Istanbul, Topkapı, Ahmet III 3505, the description of the construction of the instrument is followed by 32 numbered chapters on its use. MS Mumbai, Cama Institute, R I.86, contains 39 unnumbered chapters, the first of which describes the assembly of the rings and is not included in the Topkapı manuscript (Flora Vafea, private communication). Al-Yaʿqūbī attributes a treatise on an instrument with nine rings to Ptolemy, but a confusion with Theon appears likely: in his detailed description of the work the explanation of the construction is followed by the titles of 39 chapters on the use of the instrument, which generally correspond to the contents of the two manuscripts. The identification of the author and the work is further complicated by the fact that the Arabic sources use the general term dhāt al-ḥalaq for the meteoroscope, which is also used for the ordinary armillary sphere with seven rings. Full title: Tafsīr dhāt al-ḥalaq alladhī dhakara-hu Thayūn al-Iskandarānī (Topkapı ms, 117r, title page). Alternative titles: al-ʿAmal bi-dhāt al-ḥalaq li-Thāwun al-Iskandarānī (Mumbai ms), Kitāb fī dhāt al-ḥalaq (Yaʿqūbī), Kitāb al-ʿamal bi-dhāt al-ḥalaq (Ibn al-Nadīm, Ibn al-Qifṭī), Kṯāḇā ḏ-sāʿūrūṯ ḥūḏrē nḥāšāyē (Bar Hebraeus).

Text: [Istanbul, Topkapı, Ahmet III 3505]

(117v–133r) هذا كتاب تفسير ذات الحلق الذي ذكره ثيون الإسكندرانيّ. إنّ الحكماء عملو〈ا〉 للذي عملو⟨ا⟩ أمثالًا للفلك ليعرفو⟨ا⟩ بها حساب تداوير الفلك واختلاف الليل والنهار في أقاليم الأرض وقياس مسير طول الشمس والقمر والكواكب المتحيّرة وعرضها ومعرفة جميع ما يحتاج إليه من العلم النجوم الذي وضعوه في القوانين وهي تسع حلقات. — فينبغي لمن أراد أن يعمل لمعرفة الطول بتقدير المسير أن يبدأ فيقدر ذلك حتّى يعلم كم مقدار الجزء هناك من مسير الأيّام والفراسخ والأميال ثمّ نعمل ذلك فلا نخطئ إن شاء الله. تمّ الأبواب.

Bibl.: al-Yaʿqūbī, Taʾrīkh Ibn Wāḍiḥ (ed. HoutsmaM. T. Houtsma, Ibn Wādhih qui dicitur al-Jaʿqubī, Historiae. Pars prior Historiam ante-Islamicam continens, Leiden: Brill, 1883, vol. I, pp. 154–157; English tr. Gordon et al.Matthew S. Gordon, Chase F. Robinson, Everett K. Rowson and Michael Fishbein, The Works of Ibn Wāḍiḥ al-Yaʿqūbī. An English Translation, 3 vols, Leiden: Brill, 2018, vol. II, pp. 420–424); Ibn al-Nadīm, Fihrist (ed. FlügelGustav Flügel, Kitâb al-Fihrist, 2 vols, Leipzig: Vogel, 1871–1872, vol. I, p. 268; German tr. SuterHeinrich Suter, ‘Das Mathematiker-Verzeichniss im Fihrist des Ibn Abî Jaʿḳûb an-Nadîm’, Zeitschrift für Mathematik und Physik. Supplement 37 (1892), pp. 1–87, pp. 21 and 53; English tr. DodgeBayard Dodge, The Fihrist of al-Nadīm. A Tenth-Century Survey of Muslim Culture, 2 vols, New York / London: Columbia University Press, 1970, vol. II, p. 641); Ibn al-Qifṭī, Taʾrīkh al-ḥukamāʾ (ed. LippertJulius Lippert, Ibn al-Qifṭī’s Taʾrīḫ al-ḥukamā, Leipzig: Dieterich, 1903, p. 108); Bar Hebraeus, Chronicon Syriacum (ed. BedjanPaul Bedjan, Gregorii Barhebraei. Chronicon syriacum. E codd. mss. emendatum ac punctis vocalibus adnotationibusque locupletatum, Paris: Maisonneuve, 1890, p. 54; English tr. Budge, p. 54). — Martin Klamroth, ‘Über die Auszüge aus griechischen Schriftstellern bei al-Ja‘qûbî’, Zeitschrift der Deutschen Morgenländischen Gesellschaft 42 (1888), pp. 1–44, here pp. 19–20 and 20–23; Moritz Steinschneider, Die arabischen Uebersetzungen aus dem Griechischen, Leipzig: Harrassowitz, 1897, pp. 341–342; KrauseMax Krause, ‘Stambuler Handschriften islamischer Mathematiker’, Quellen und Studien zur Geschichte der Mathematik, Astronomie und Physik, Abteilung B: Studien 3 (1936), pp. 437–532, p. 525 (no. 16); Otto Neugebauer, ‘The Early History of the Astrolabe. Studies in Ancient Astronomy IX’, Isis 40 (1949), pp. 240–256, esp. p. 242; GAS VFuat Sezgin, Geschichte des arabischen Schrifttums. Vol. V: Mathematik bis ca. 430 H., Leiden: Brill, 1974, pp. 173 and 180–184; GAS VIFuat Sezgin, Geschichte des arabischen Schrifttums. Vol. VI: Astronomie bis ca. 430 H., Leiden: Brill, 1978, pp. 101–102; Richard Lorch, ‘The “Meteoroscope” Attributed to Theon of Alexandria’, in I. International Congress on the History of Turkish-Islamic Science and Technology. İstanbul Teknik Üniversitesi, 14-18 September 1981. Proceedings, Istanbul: İstanbul Teknik Üniversitesi. Bilim ve Teknoloji Tarihi Enstitüsü, 1981, vol. I, pp. 33–38.

Ed.: An edition, translation and study of this work are currently being prepared by Flora Vafea.