Liber proiectionis radiorum stellarum
This short text on the projection of rays is attributed to Ptolemy in two manuscripts: ‘Explicit liber proiectionis radiorum sapientissimi Ptholomei’ (Madrid, BN, 10063 (olim Toledo 98-19)) and ‘Capitulum proiectionis radiorum secundum Ptholomeum’ (Vienna, ÖNB, 3124), while one manuscript makes it the last chapter of Alcabitius’s Introductorius (Oxford, BL, Savile 17). In the other copies the text is anonymous, but the attribution to Ptolemy is however implicit, for in most manuscripts, including the earliest one (Pommersfelden, GSB, 60 (2633), copied c. 1200), the text follows the Quadripartitum in the translation of Plato of Tivoli (A.1.2) without a break, and in five instances (Munich, BSB, Clm 3857; Paris, BnF, lat. 7302; Vatican, BAV, Barb. lat. 328; ed. 1493; ed. 1519), it is even considered part of the Quadripartitum, as is also the case in commentaries C.2.3, C.2.4. The connection between the projection of rays and Ptolemy was already clear in Albumasar’s Introductorium maius VII.7, whose title reads ‘Differentia VII in proiectione radiorum planetarum secundum opus Tholomei’ in John of Seville’s translation (ed. R. Lemay, Abū Maʿšar al-Balḫī [Albumasar]: Liber introductorii maioris ad scientiam judiciorum astrorum, Napoli, 1995-1996, V, 308; Arabic text in K. Yamamoto, C. Burnett, The Great Introduction to Astrology by Abū Maʿšar, Leiden, 2019, I, 795). Contrary to Lemay’s opinion (ibid., IV, 56), however, the present text does not derive from Albumasar’s chapter.
‘(Munich, BSB, Clm 3857) Cum proiectiones radiorum stellarum scire volueris, scias gradus ascendentis — (43vb) et quod collectum fuerit erit locus radiationis equate.’
F. J. Carmody, Arabic Astronomical and Astrological Sciences in Latin Translation. A Critical Bibliography, Berkeley-Los Angeles, 1956, 21 (nos 43-44).