Credit: Wellcome Library, London. Wellcome Images images@wellcome.ac.uk http://wellcomeimages.org Canones Arzachelis in tabulas Toletanas. Theorica planetarum. Wrritten in a neat book hand in double column of 39 lines to a column. Initial with marginal decoration in alternate red and blue, and blue and red. Paragraph marks in alternate red and blue, headings in red. Illustrated wth 8 geometrical figures in red, and 3 large astronomical diagrams in black, and geometrical figure in black: with a table of sines in red (fol. 4v), and another in red and black (fol. 25) of 'Motus planetarum in die secundum ptolomeum'. Fol. 1 (red) Incipiunt canones super tabulas/astronomie. (Text begins) Quonian cuiusque/accionis quantitatem temporis/metitue... 19v, col. 2 ... Scies, quoque diem et horam/et quantitatem eclipsium si deus uo/lerit.//Expliciunt canones astrono//mie de gracias. 20 (red) Incipit theorica planetarum. CIrculus/dicitur eccentricus uel egisse cuspidis... 25, col. 2 ... erunt/uincti lumine ipsi planete et non corporaliter.//Explicit theorica planetarum.///[Table 'Motus planetarum']. 26 Tree of Species. 26v Zodiacal diagram. 27 Armillary sphere. 27v Diagram of the Spheres. 28 Geometrical figure, with notes by a contemporary hand. 28v (red) De vera primatione./Si vis scire diem et horam et punctum reuo/lutionis lune... In this note an example is given based on the year 1286.

Ot these two works the 'Theorica planetarum' is probably by Gerard of Cremona, himself, but the 'Canones' are a translation by him of the 'Toledan Tables' originally edited by Iban al-Zarquala or al-Zarqali [c. 1029-c. 1087], an Arabic astronomer of Corodova [cf. Sarton. 'Introduction to the History of Science', VOl. I, pp. 758-759]. 14th Century Gerardus Cremonensis (1114-1187) Published: -