Canones vel operationes in operando quadrante
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This elegant codex on the functions of the astrolabe quadrant includes computational methods for determining altitude, latitude, the positions of stars, and the twelve houses of the horoscope. It is open to a diagram depicting the quadrant’s use in locating a star, including an appropriately positioned astronomer in the margin, and two tables indicating the ascensions of the zodiac signs and the attributes of the fixed stars.
Other illustrations and tables in this manuscript include the back of the quadrant (fol. 5v), two diagrams showing how to measure the height of a tower (fols. 21v, 23v), a square diagram showing the computation of the astrological houses for Nov. 14, 1501 (fol. 16v), and tables providing the hours of day and night (fol. 10r) as well as sunrise and sunset (fols. 15r-15v) at 45°N. Written in Southern Italy, it is bound in a reused leaf from a twelfth-century copy of Augustine’s In Iohannis evangelium tractatus, written in the Bari form of Beneventan script.