Perpetual V

The Gregorian calendar is an imprecise instrument. Months of 28, 29, 30, and 31 days exist for historical and astronomical reasons that have nothing to do with mechanical logic. The Perpetual V solves this by encoding the calendar’s irregularities into a cam-and-lever system designed in 1979 by our founder, revised in 2008, and still manufactured in-house.

The Mechanism

The perpetual calendar module adds 312 parts to the base movement. The date-change mechanism advances at midnight through a series of jumps: instantaneous for the date, gradual for the month. The difference in behaviour is intentional : the date announces itself; the month turns quietly.

The Moonphase

Two rotating discs, each painted with a hemisphere of the moon. The display is driven by a 135-tooth wheel that advances one tooth every 24 hours and 44 minutes. Over 122 years, the accumulated error amounts to one day. This is a mechanical truth: no moonphase display is perfectly accurate. Ours is simply the least inaccurate.

The Dial

Slate blue enamel. The moonphase aperture at 6 o’clock is surrounded by a chapter ring in polished white gold, each hour marker applied individually. The month, day, and date are displayed through apertures in the upper hemisphere of the dial: three windows that read left to right, in the natural order of a date.

Setting

The Perpetual V requires no manual correction until March 1st, 2100, when those who carry it forward will need to advance the date by one day to account for the century’s non-leap year.