Watch Complications: The Calendar
This complication provides an indication of various aspects of the calendar, for example the date, the month and the year. Calendar watches can be very simple or incredibly complicated depending on just how much information they provide and how often they need manual adjustment to retain accuracy. Some of the most expensive watches in the world feature calendar complications and can sell at auction for many £millions. In this article we look at the different types of calendar complication.
A simple calendar provides only the date and requires manual adjustment for any month where there are fewer than 31 days. The date may be displayed digitally via an aperture in the watch dial or by means of a hand pointing at the days of the month arranged in a circle or arc. Some simple calendars also display the day, so called day-date watches.
An annual calendar displays not only the date, but also the day and the month. It is configured to show the date correctly for months with fewer than 31 days, but does need adjusting once a year at the end of February due to the leap year anomaly, hence the term annual calendar.
A perpetual calendar goes one step further and takes into account the leap years. In fact a perpetual calendar is so complicated that it will not need adjusting until the year 2100. This is because every year that is exactly divisible by four is a leap year, except years that are exactly divisible by 100. However, these centurial years are leap years if they are exactly divisible by 400. For example, the years 1700, 1800, and 1900 are not leap years, but the year 2000 is. The next centurial year that is not a leap year is therefore 2100. Perpetual calendars will follow their 4-year-mechanism and they will display 29th February even in the year 2100.
Secular perpetual calendar
The secular perpetual calendar is so sophisticated that it has hardly ever been built into a watch. Not even the Patek Philippe 1933 Graves Supercomplication sold by Sotheby’s in November of last year for £13.4 million had this feature, although certain Patek pocket watches such as the Calibre 89 do. The secular perpetual calendar accounts for the 400-year-rule, which means that only these calendars will jump directly from 28th February to 1st March in the year 2100.
If you have any watches that you would like to sell, please contact Simon Rufus, watch specialist at Grand Auctions, Folkestone, Kent for further details.