His great-grandfather was Abraham [Diogo Rodriguez] (1450?‒_post_ 1510) _de_ Samuel _de_ Abraham Zacut, the astronomer, mathematician and historian. In 1473, while a professor in the University of his native town, Salamanca, he wrote his world-famous: ביאור לוחות׃ [B. M.] (Astronomical Tables), and here he became acquainted with Christopher Columbus (1446?‒1506). His pupil Joseph Vecinho (Vizino) [Diego Mendes], physician to João II., the Great (1455‒1495), King of Portugal (1481‒1495), translated the work into Latin. It was printed by a Jew, Samuel D’Ortas, at Leiria in 1496, and entitled “Almanach Perpetuum.” Dr. Vecinho presented a copy to Columbus, which he always carried with him and consulted on his voyages, deriving invaluable help from it. It was this very book that he used to predict the eclipse of the moon, which so terrified the Indians in Jamaica that they became obedient to him, and furnished his party food. After his death it was found in his library. On the margins are calculations in his penmanship, which were doubtless made to verify those of Zacuth.¹ ¹ _The Authentic Letters of Columbus._ By William Eleroy Curtis, ... Chicago, ... 1895, _pp._ 115‒116. On the exile from Spain, 2 August, 1492, the author went to Lisbon, where he was appointed astronomer and historiographer to João II. He was of material assistance to the great navigator Vasco da Gama (1460?‒1524), in preparation of his voyage to India. The ships were provided with Zacuto’s newly perfected iron astrolabes, which hitherto had been of wood. He was highly esteemed by da Gama, who took leave of him on the 8 July, 1497, in the presence of his entire crew. Portugal also expelled the Jews, so he fled with his son Samuel to Tunis, and here in 1504 he wrote his famous ספר יוחסין which is a chronological history of the Jews from the Creation up to 1500. It was first printed in Constantinople in 1566 [B. M.], and an issue edited by Herschell Filipowski (1817‒ 1872) was published in London in 1857, some copies of which were printed on vellum [B. M.]. Tunis being invaded by Spain he emigrated to Turkey, where he died some time after 1510. XXII. JACOB JUDAH ARYEH D̅E LEON