Quote:The astronomical details are followed in the third paragraph by the explanation of the calendar. The latter consists of eight concentric circles, of which the innermost gives the dates of Easter for ninety-five years, from April 1, 1453, to April 10, 1547; when Easter falls in April, A is written in the small compartment, when in March, M; leap years are designated by B (“bissextile years”).

The second circle shows the names of the months, beginning with March, which was officially reckoned the first month of the year in the Republic of Venice until as late as 1797 [8]; it also tells the day, hour, and minute when the sun enters each of the twelve signs of the zodiac.

[8] H. Grotefend, Zeitrechnung des deutschen Mittelalters und der Neuzeit, Vol. 1, Hannover, 1891, p. 203 (reference kindly suggested by Dom Hugh G. Bévenot of Weingarten Abbey, Württemberg, Germany).