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Ptolemaeus Arabus et Latinus

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Work B.13

Liber de compositione universalis astrolabii


‘(Fermo, BC, 85) Incipit in nomine Dei pii et misericordis liber (added above the line: Tolomei) de compositione universalis astrolabii. Ptolomeus igitur Mercurii incedens vestigiis in libro suo qui vocatur Almagesti de motu sic ait: Ait enim omnis motus aut de puncto aut ad punctum — cum una eademque utrique conveniat ad plenum dicetur. Explicit liber Ptolomei de compositione astrolabii quem scilicet Robertus Cestrensis in civitate Londonie ex Arabico in Latinum transtulit, era millesima centesima LXXXVa.’


On the construction of the astrolabe.


According to the colophon, this text was translated from Arabic by Robert of Chester (‘Robertus Cestrensis/Castrensi’) in London in ‘era 1185’, i.e. in 1147 A.D. However, Kunitzsch, 490, has shown that this work is not a translation, but a Latin compilation that borrowed from previous works on the astrolabe. This, of course, does not disqualify Robert of Chester as the author or compilator.


Some sections of the oldest corpus on the astrolabe, put together from Arabic sources in Catalonia c. 1000, were already attributed to Ptolemy: see Horologium regis Ptolomei, or part C of the Sententie astrolabii, in 22 chapters (ed. J. M. Millàs Vallicrosa, Assaig d’història de les idees físiques i matemàtiques a la Catalunya medieval, Barcelona, 1931, 280-288); and Compositio astrolapsus secundum Ptolomeum, inc. ‘Iubet rex Ptolomeus bene politam fieri tabulam…’ (ed. ibid., 322-324). The Sententie astrolabii as a whole is attributed to Ptolemy in Sevilla, BCC, 5-2-16, s. XII, f. 1r-8r (‘Incipit liber de labore vel scientia astrolapsus et horologii interpretatus de Arabigo in Latinum a rege Tolomeo’). The De utilitatibus astrolabii is attributed to Ptolemy in five MSS (Avranches, BM, 235, s. XII, f. 58r: ‘Capitula Ptolomei de astrolabio’ and ‘Regulae Ptolomei super astrolabium’; London, BL, Addit. 17808, s. XI, f. 73v: ‘Regulae ex libris Ptolomei regis de compositione astrolapsus’; Los Angeles, J. Paul Getty Museum, Ludwig XII.5, s. XII, f. 101v-103r: ‘Incipit Spera Tholomei vel astralabium ipsius’; Paris, BM, 3642, s. XIII, f. 56v: ‘Tractatus Tholomei de astrolapsu’; Paris, BnF, lat. 14065, s. XI-XII, f. 48v-51r: ‘Regulae ex libris Ptolomei regis de compositione astrolapsus’). According to Charles Burnett (‘King Ptolemy and Alchandreus the Philosopher: The Earliest Texts on the Astrolabe and Arabic Astrology at Fleury, Micy and Chartres’, Annals of Science 55 (1998), 329-368: 341), the attribution of these texts to Ptolemy would rather be ‘the responsibility of later redactors and scribes, and not to the original translator/compiler of the Latin texts from Arabic sources’. See also E. Zinner, ‘Über die früheste Form des Astrolabs’, Naturforschende Gesellschaft Bamberg 30 (1947), pp. 9-22; E. Zinner, ‘Cl. Ptolemaeus und das Astrolab’, Isis 41 (1950), 286-287.


F. J. Carmody, Arabic Astronomical and Astrological Sciences in Latin Translation. A Critical Bibliography, Berkeley-Los Angeles, 1956, 19 (no. 19, also nos. 14-18); P. Kunitzsch, Glossar der arabischen Fachausdrücke in der mittelalterlichen europäischen Astrolabliteratur, Göttingen, 1983, 489-491. For works on the astrolabe attributed to Ptolemy in Arabic, see F. Sezgin, Geschichte des arabischen Schrifttums, V: Mathematik, Leiden, 1974, 171-174 (nos. 2-3), and VI: Astronomie, Leiden, 1978, 95 (no. IV).