Jābir ibn Aflaḥ’s al-Kitāb fī l-Hayʾa (‘Book of Astronomy’) – better known in modern scholarship as Iṣlāḥ al-Majisṭī (‘Correction of the Almagest’) – translated by Gerard of Cremona. This text is a new edition of the Almagest in nine books as follows: trigonometry (Book I); spherical astronomy (II = Almagest I-II); Sun (III = Almagest III); Moon (IV = Almagest IV-V.10); description of an observational instrument, parallaxes, distances and eclipses (V = Almagest V.11-VI]; fixed stars (VI = Almagest VII-VIII); planetary spheres (VII = Almagest IX-XI); retrogradation (VIII = Almagest XII); and planetary latitudes (IX = Almagest XIII). The work includes criticism of Ptolemy on several points (see also C.1.18). Geber’s Liber super Almagesti gave rise to a supercommentary (C.1.6) and was used as a source in commentaries C.1.3 and C.1.21.

Note Four manuscripts (Dresden, SLUB, Db. 87; Vatican, BAV, Vat. lat. 2059; Vienna, ÖNB, 5392; Vienna, ÖNB, 10905) have a short appendix on spherical trigonometry, which is essentially a commentary on I.13-14: ‘Nota in figura tredecima libri primi Geber quod arcus AG subtensus recto potest esse quarta circuli — In eadem figura potest contingere quod uterque duorum arcuum AG AB sit maior quarta circuli et quod uterque sit minor, sed Geber’. This appendix breaks off mid-sentence but it is found in a longer – and no doubt original – version in three manuscripts which do not have Geber’s text (Paris, BnF, lat. 7377B, f. 41r-42v; Madrid, BN, 10010, s. XIII, f. 51v-52r; and Vatican, BAV, Reg. lat. 1268, s. XIV, f. 210r-210v) among a substantial set of notes discussing various texts, including Theodosius’s Spherica, Geber’s Liber super Almagesti, Menelaus’s Spherica and Ametus filius Josephi’s Liber de proportione et proportionalitate (these notes appear most complete in Paris, BnF, lat. 7377B, f. 38r-60v: ‘Hec probationes sunt necessarie in theoremate undecimo partis secunde libri Theodosii de speris…’; and only partial in Madrid, BN, 10010, f. 50v-52v; and Vatican, BAV, Reg. lat. 1268, f. 207v-211v). This appendix is discussed and edited by Lorch, ‘Jābir ibn Aflaḥ’ (1995), 12-20 (15-18 for the edition, where the longer form includes the three final chapters numbered 14(iii)-14(v)). In Vienna, ÖNB, 5392 and Vienna, ÖNB, 10905, the appendix is followed by an additional chapter on VII.14 (‘Nota in figura decima quarta septimi libri Geber quod centrum orbis signorum potest esse infra triangulum — ad dyametrum circuli ABG quod proponebatur’) and by further notes on various chapters (‘Annotationes in Gebrum. Textus fo. 1. Et de eis. Prima difficultas propter narrationem prachticae et theorice — orbe signorum aliud est solus meridiem ab eo’), as already noted by Lorch, ‘Jābir ibn Aflaḥ’ (1995), 14.

Text ‘(Cesena, BCM, Plut. S.XXVII.2) (1ra-3ra) [preface] Verba Geber filii Afla Yspalensis. Scientia species habet quarum melior post scientiam fidei — cuius socius non est. Et hinc incipio premittere illa quorum premissio necessaria est. (3ra-19rab) [book i] Tractatus primus de propositionibus huius libri vel theorematibus. Et incipiamus exponere intentiones nominum usitatorum in eo, dico ergo polus circuli — per illam quantitatem, et illud est cuius voluimus declarationem. Explicitus est tractatus primus. (19rb-36ra) [book ii] Initium tractatus secundi de ordinibus specierum huius scientie. Inquit Ptholomeus primum a quo nos oportet incipere in hoc libro est consideratio in summa dispositionis totius terre apud totum celum — et sinus arcus eius est notus, ergo ipse est notus, et illud est quod voluimus. Finit tractatus secundus huius libri. (36ra-43ra) [book iii] Incipit tractatus tertius huius libri in motu Solis medio. Et postquam declaratum est illud cuius demontratio precessit de istis scientiis particularibus — dies equales ad dies diversos, et illud est quod voluimus declarare. Completus est tractatus 3 huius libri. (43ra-57ra) [book iv] Initium tractatus quarti in Luna. Et postquam declaratum est ei totum quod premissum est de esse Solis, possibile est ei inquirere de re Lune — diametri orbis revolutionis, et illud est cuius voluimus declarationem. Finit tractatus quartus huius libri. (57ra-78rb) [book v] Initium tractatus quinti in acceptione instrumenti quo scitur diversitas aspectus Lune. Et propterea quod non est quantitas spere terre apud speram orbis Lune — ergo longitudo puncti L ab illo puncto est nota, et illud est cuius voluimus declarationem. Expletus est tractatus quintus huius libri. (78rb-95ra) [book vi] Incipit tractatus secundus (!) de stellis fixis. Quod stelle fixe sunt commitantes proprietates suorum locorum cum quantitate spatii unius semper inter se ad invicem. (78va) Inquid Ptolomeus: Et postquam narravimus in eis que precedunt hunc sermonem illud quod accidit in spera recta — qualiter inveniantur quantitates eorum in fine libri in stellis currentibus secundum rectitudinem. Finitus est tractatus sextus. (95ra-115rb) [book vii] Incipit tractatus septimus in stellis <quinque> currentibus. Et quia ostensum fuit ei totum cuius precessit declaratio de esse Solis et Lune et stellarum fixarum — et Martis super sedecim quadraginta Cancri. Expletus est tractatus septimus huius libri. (115rb-123ra) [book viii] incipit tractatus octavus in statione stellarum quinque et earum retrogradatione. Propterea quod vir rememoratus est inventionis stationis stellarum secundum quod non sit ei nisi diversitas — super punctum L positum singulariter. Completa est eius declaratio. Completus est tractatus octavus. (123ra-134ra) [book ix] Incipit tractatus nonus in latitudinibus planetarum. Et propterea quod remanserunt de scientia stellarum quinque hesitantium due res — sunt digniores et evanescant et destruantur. Completa est eius declaratio. Completus est tractatus nonus et est ultimus libri. Hunc librum Geber transtulit in Toleto magister Gerardus Cremonensis de Arabico in Latinum.’

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Modern ed. None. The Arabic text has been partly edited by Bellver, Críticas.