Jacob became known by a series of
Hebrew translations of
Arabic scientific and philosophical works, and above all by two original works on
astronomy. His translations are: • the
Elements of
Euclid, divided into fifteen chapters • the treatise of
Qusta ibn Luqa on the
armillary sphere, in sixty-five chapters •
Sefer ha-Mattanot, the
Data of Euclid •
Autolycus'
On the Moving Sphere •
Theodosius'
Spherics •
Menelaus'
Spherics • ''Ma'amar bi-Tekunah,
or Sefer 'al Tekunah,'' in forty-four chapters • a treatise on the use of the
astrolabe • compendium of the
Almagest of
Ptolemy • ''Iggeret ha-Ma'aseh be-Luaḥ ha-Niḳra Sofiḥah'' • preface to
Abraham bar Ḥiyya's astronomical work • an extract from the
Almagest on the arc of a circle • "Ḳiẓẓur mi-Kol Meleket Higgayon,"
Averroes' compendium of the
Organon (Riva di Trento, 1559) • Averroes' paraphrase of books xi–xix of
Aristotle's history of animals • ''Mozene ha-'Iyyunim,
falsely attributed to Ghazali, including also a large part deriving from the Encyclopedia of the Brethren of Purity (Rasā’il Ikhwān al-Ṣafā’'') The two original works of Jacob are: • a description of the astronomical instrument called the quadrant (Bibliothèque Nationale, Paris, MS. No. 1054), in sixteen chapters, the last of which shows how to construct this instrument. This was translated several times into Latin (once by
Armengaud Blaise) • astronomical tables, beginning with 1 March 1300 (Munich MS. No. 343, 26). These tables were translated into Latin and enjoyed great repute. ==See also==