ouses and to the ascendant. He also provides the longitudes and latitudes of the main cities; finally he devotes a chapter to the fixed stars. In the second part of the canons, Zacut explains the circumstances of the other planets (Saturn, Jupiter, Mars, Venus, and Mercury) and devotes one chapter to the Jewish, Christian, Islamic, and Persian calendars. This second part comes to a close with Chapter 19, where he explains the movements of the seven planets and of the lunar node (Dragon Head). After the canons, he gives the tables for the material discussed in these 19 chapters. The structure of the tables is influenced by Jacob Poel (Bonet Bonjorn), an intermediary who connected the work of Gersonides and Zacut. More than 50 manuscripts are known of these tables, of which we should particularly note MS Sassoon 823 for its detailed “representation” of its catalog of stars. In addition to mentioning Bonet Bonjorn, whom the translator Salaya refers to by his Hebrew name Jacob Poel (Po ‘el meaning “the artisan”), Zacut mentions the Jewish scholar Yehuda ben Aser. There are also references to the tables and calendar of King Alfonso X.
The canons of the Almanach perpetuum also exist in another Spanish version that was made by the same José Vizinho who made the Latin translation. A copy of this Spanish version is kept in an incunabulum of the Colombin Library of Seville's Cathedral. It consists of 23 chapters dealing with the ascendants of the 12 houses, explanations of the positions of the Sun and the Moon and their eclipses, the places and movements of the planets, and a reference in the last chapter to an “animodar.”
Zacut's empirical interests are indicated by his observation in 1474 of the Moon covering the star of the spike in Virgo's hand, when this constellation was approximately in the middle of the sky. Other astronomical observations attributed to him are an occultation of Venus by the Moon in July 1476, and a total solar eclipse in June 1478.
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Chabás, José and Bernard R. Goldstein (2000). Astronomy in the Iberian Peninsula: Abraham Zacut and the Transition from Manuscript to Print. Philadelphia: American Philosophical Society.
Flórez, Cirilo et al. (1989). La ciencia del cielo. Salamanca: CAJA DE AHORROS.
Romano, David (1992). La ciencia hispanojudía. Madrid: Mapfre.
Noel M. (1977). “A Summary of the Derivation of the Parameters in the Commentariolus
from the Alfonsine Tables with an Appendix on the Length of the Tropical Year
in Abraham Zacuto's Almanach Perpetuum.” Centaurus 21: 201–213.