Very rare edition of the Veronese astronomer and mathematician Pietro Pitati, author of numerous astronomical treatises and almanacs. 
Pitati's name remains linked to chronological studies and calendars. The inadequacy of the Julian calendar and of the rules established by the Council of Nicaea for the calculation of Christian movable feasts - Easter in primis - had been known for at least four centuries, but the numerous reform proposals had not found outlets. While the Council of Trent did not deal directly with the reform of the calendar, the last session recognized the urgency of the matter by delegating its care to the pontiff. The problem of the date of Easter had already been addressed by Pitati in his first work, the Paschales atque noviluviorum mensurni canones addressed to Paul III (1537); shortly afterwards he arrived at the rule still in use to keep the date of Easter close to the vernal equinox, which now fell on March 10 (rather than 21 as assumed by the Council of Nicaea).  The origin of the rule is not mentioned either by Giglio or by the German Jesuit Christopher Clavius in his defense of the Gregorian reform (1603), authors who dealt with the reform of the Calendar, but modern critics agree in assigning its origin to Pitati.
Riccardi I, 285 and 286.