Sepher Ivronoth [astronomy and calculations of intercalation and the Jewish calender]

A Rare Copy, Complete With All Volvelles, Fully Assembled, in Their Original State and in Fine Condition. The Jewish calendar is lunisolar; the months are reckoned by the moon and the year by the sun. The astronomical expertise required to make the necessary adjustments, mandated an interest in astronomy for religious Jews. Maimonides devotes an entire section of his Mishneh Torah to what he lists as a positive commandment “to know how to determine which is the first day of each month of the year.” Sepher Ibronoth was prepared by R. Beilin as a manual “to help an individual fulfil the commandments.” This edition is particularly beautiful with fine illustrations and volvelles for calculations. See A. J. Karp, From the Ends of the Earth-Judaic Treasures of the Library of Congress, (1991) pp.197-8.