The central block

Fit into a structure made from sculpted and painted wood, the central unit offers a number of indications on a series of brass dials.

It also holds the four driving mechanisms, which provide motion to the automated figures and clock hands. The central pendulum swings to mark the seconds.

The central unit’s various indications are divided into three sections. The dials are circular and give a partial view of the mechanisms behind them. You can see the escape wheel, which drives the second hand.

The middle section has 17 dials organised in a flower shape. They provide the current year’s Roman indiction (a year’s position in a 15-year cycle), dominical letter, epact (a quantification of the difference between the solar and lunar calendars), solar cycle, and golden number, which are collectively used in the computus paschalis (the calculation of the date of Easter, the central date in the calendar of the Catholic Church). The middle section’s dials come to life at the stroke of midnight each 31 December to 1 January.

On either side of the middle section are two sections with ten dials each. Eight of those dials indicate the hour and minute of a meridian. They contain 24 markers: 12 white ones for day hours and 12 blue ones for night hours.

At the top of the left-hand section, two dials indicate the Chaldean cycle—the periodic return of solar and lunar eclipses. These dials have 18 markers and their hands advance at the start of every year.

At the top of the right-hand section, one dial indicates whether the current year is a common year or a leap year and the other indicates if the current century begins with a common year or a leap year. The latter dial contains 11 markers corresponding to 11 periods of 400 years. As such, its hand advances by one marker every 400 years !