After the pleasure of the ear with the hint on the striking mechanism how about lifting outr eyes to the sky.
The "Grand oeuvre " or Magnum Opus" as VC calls it will feature a star chart representing the consetallins visible in the night sky from the owner's home city , around its edge are inscribed the months of the year.
The sidereal or star time can be read from the corresponding outer 24-hour scale by choosing a star at the appropriate time and tracking that same star at it rotates, wherever the chosen star is found in relation to the 24-hour scale indicates to the user the current sidereal time.Sidereal time is the sidereal day which is the interval between two consecutive upper transits of the vernal point in the plane of the meridian. Since in practice this can be measured as the earth's rotation with respect to distant celestial objects. The sidereal day is 23 hours, 56 minutes and 41 seconds. The sidereal year contains one more day than the solar year. With the stars used as a point of reference, sidereal time enables a more regular scale of time than that afforded by using the sun as a reference. Naturally the sidereal sky chart is mainly used during hours of darkness when the star constellations are visible and therefore the dominant indications on the present watch are for the hours between 8pm in the evening and 4 am in the morning. Concentric around the outer border is the sector scale for the retrograde date of the perpetual calendar, this function self-corrects for the appropriate number of days in each month including leap-years, at the end of each month the hand instantaneously jumps back to its start point.