Complication · Calendar & astronomy

Triple Calendar

Partially verified

A calendar complication displaying day, date and month simultaneously (often alongside moon phase), but without the perpetual calendar's automatic leap-year and month-length logic, so it requires manual correction after every short month.

Definition

Historical origin

A recognised category of complicated watch from at least the early twentieth century, sitting between the simple date-only calendar and the full perpetual calendar in both display richness and mechanical complexity; often produced alongside moon phase as a 'triple calendar with moon phase' combination.

How it works

Three separate subsidiary indications — day (via a day disc or rotating day ring), date (via a date ring or hand) and month (via a month disc) — are each advanced once every 24 hours by the same underlying motion-work trigger, in the same manner as the simple calendar but tripled across three displays.

Because none of the three discs is linked to a program cam encoding variable month lengths, all three must be advanced manually at the end of every month with fewer than 31 days, and the day disc must also be corrected whenever the date is corrected out of sync with the actual day of the week.

This makes a triple calendar mechanically simpler than an annual or perpetual calendar (no month-length program wheel is required) but functionally more demanding of the owner, since correction is needed roughly seven times a year rather than once or never.

Pocket watch context

A well-established nineteenth- and early twentieth-century pocket watch calendar format, frequently combined with moon phase in a single calendar dial layout on mid-to-high-grade watches.

Wristwatch context

Produced today largely as a classically styled complication referencing this historical calendar-with-moon-phase dial layout, valued for its display richness relative to its mechanical simplicity compared with a perpetual calendar.

Identification

Day, date and month all shown simultaneously, typically in apertures or subsidiary dials
Requires manual correction at the end of every month shorter than 31 days, unlike an annual or perpetual calendar
Very frequently paired with a moon phase display on the same dial

Servicing notes

With three separate calendar trains to keep synchronised, correction after service (particularly after the watch has stopped) needs to be done in the correct sequence to avoid forcing a disc against its stop; this is routine but calibre-specific work for a watchmaker.

General guidance only. Complicated mechanisms should be assessed and serviced by a qualified watchmaker or clockmaker specialist, not adjusted at home.