Obj. ID: 39291  Evronot by Shimon bar Yonah Katz, Żółkiew, 1770

This text was prepared by William Gross:

Sefer Evronot is a book for calculating of the months and the seasons of the Jewish year. Because the months are reckoned by the moon and the year by the sun, astronomical expertise was required to make the necessary adjustments, in order to ensure that the holidays are celebrated at the proper time. Interest in astronomy was thus mandated for religious Jews. Maimonides in fact devotes an entire section of his Mishnah 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.”
Ever since the 1615 edition of Sefer Evronot from Lublin, the name of Eliezer b. Jacob Belin Ashkenazi has appeared as "author" on title pages of sifre evronot. Although his name does not even appear on the title page of that edition, which he in fact brought to press, Belin came to be credited with the Jewish computus to the virtual exclusion of all other individuals who preceded him. Some contemporary bibliographers and catalogers have followed suit, attributing all sifre evronot to this elusive "author", about whom very little is known.
Thirteen editions of this important work appeared up to the middle of the 19th century. This edition contains numerous illustrations, and diagrams, including one of a hand, "lu'ach ha-yad'.
This edition includes a list of the fairs in the lands of Poland, Russia and Ashkenaz.