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

BEILIN, ELIEZER BEN JACOB

Israel ben Moses

Offenbach

1722

Title within architectural arch featuring Moses and Aaron, with cherubs flanking a zodiac sphere. Numerous mathematical tables and illustrations. Woodcut illustrations of hand palms on ff.23v. and 24r. Spherical charts on ff. 25 and 28. Single sphere tipped between ff.36v and 37r. Lacking volvelles.

Vinograd, Offenbach 63

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 Beilin as a manual “to help an individual fulfil the commandments.” See A. J. Karp, From the Ends of the Earth-Judaic Treasures of the Library of Congress, (1991) pp.197-8 For a rare complete copy with all volvelles sold at auction, see Kestenbaum & Company, Sale X, June 27th, 2000, Lot 28