These days we take for granted the fact that the mechanical watch on our wrist can reliably tell us the precise date as well as the time.
If you stop to think about the complexity of the Gregorian calendar for a moment, however, you begin to realise that this is a lot more remarkable than it first appears. Firstly, there’s the alternating 30- and 31-day months to contend with (thank you, Caesars Julius and Augustus!), then there’s February, which only has 28 days, unless of course it is a leap year, and yet some timepieces can factor in all these adjustments and more, for hundreds of years without interruption and without any assistance required from their owners.
Ever since watchmakers began creating complications several centuries ago, they have been attempting to find ways to monitor the date, the days of the week, the months, the moon’s phases, the sun’s path, and other astronomical idiosyncrasies more effectively. Civilisation has been built upon the accurate recording of time and date, with calendars allowing us to plan for the seasons, take into account ceremonial occasions, and mark important events. As such, the haute horology industry grew partly out of an obsession with precisely measuring our calendar.
From the humble date watch, which simply indicates the day of the month, to the perpetual calendar, which can demonstrate the day, date, month, and year while only needing to be adjusted once every hundred or so years, the calendar watch is an incredible example of precision engineering. Read on to learn more about some of the major different variations.
The Summation of 24 Hours: The Simple Date
The most basic form of the calendar watch is the date watch, which indicates the day of the month via an aperture on the dial. This aperture, also known as a date window, displays one part of an inner date disc that holds the numbers 1 through 31. The basic date watch is not capable of accounting for any month that has less than 31 days, which means the timepiece’s date must be corrected by its owner five times a year, in February, April, June, September, and November. The change from one day to the next can be gradual or instantaneous depending on the watch’s inner mechanism. The classic Cartier Drive de Cartier — powered by the self-winding mechanical Calibre 1904-PS MC — for instance, is the perfect example of a date watch that enjoys a gradual shift in date as the time approaches midnight. The Jaeger-LeCoultre Master Control Date on the other hand is an example of a quick-change date, where the date instantaneously changes at the stroke of midnight thanks to a jumping mechanism driven by the watch’s automatic Calibre 899/1.
I Don't Like Mondays: The Day-Date
Indicating the day of the week in addition to the date of the month is the day-date watch, also referred to as a double calendar watch. Via an additional aperture on the dial, the watch showcases one of the seven days of the week thanks to additional inner day disc. First launched in 1956, the Rolex Day-Date is one of the most recognisable examples of this type of watch and, as the first of its kind, rapidly became a favourite among celebrities and dignitaries. Today the watch is powered by one of two new-generation movements, calibre 3155 or calibre 3255 (depending on the model you choose), both of which are entirely developed and manufactured by Rolex. This self-winding mechanical movement features a day and date calendar disc mechanism, enabling the watch to indicate the precise day and date. Though some day-date watches only indicate the day using the first three letters of each day of the week, the Rolex Day-Date demonstrates each day spelled out in its entirety, hence why it remains the prime example of this category of watch.
It's All There on Your Wrist: The Full Calendar
One step up from the day-date is the full calendar watch, also known as the triple calendar watch. This timepiece indicates the day, the date, and the month of the year. If the instrument also indicates the lunar phases via an additional moon disc, then it can be considered a full or complete calendar watch. With the release of the Clifton Collection, Baume and Mercier put forth a striking version of this kind of watch. Encased in steel and paired with a rich blue dial, the Clifton 10057 is equipped with an automatic movement that boasts moon phase, week day, and month functionality, as well as a central hand that indicates the date via a peripheral date track.
The Year's Shortest Month: The Annual Calendar
Taking us into the realm of more intricate complications is the annual calendar watch. Unlike the three kinds of calendar watches mentioned previously, this type of watch only needs adjustment once per year to account for February’s unique amount of days. Months with 30 and 31 days pose no challenge as an annual calendar watch is capable of automatically adjusting the date accordingly, while still showcasing the moon phase, the day, date, and month of the year. With its three sub-dials and enlarged date window, A. Lange and Söhne’s Saxonia Annual Calendar is a stunning example of the annual calendar. Powered by the Manufacture Calibre L085.1 SAX-0-MAT, rather than indicate the day and the month via apertures, as is commonly done, this timepiece uses two sub-dials to point to the correct details, thus giving the watch a symmetrical, balanced aesthetic.
A Leap of Faith: The Semi-Perpetual Calendar
Mid-way between an annual and the much-lauded perpetual calendar is the not-so-common semi-perpetual calendar watch. As with full and annual calendar watches, this is an instrument capable of tracking the date, day, month, and current lunar phases, however, the twist comes in the fact that a semi-perpetual watch needs adjustment just once every 1,461 days or four years. This single adjustment is required to take into account the Gregorian calendar leap year, otherwise, a wheel that rotates once every four years powers the calendar indications. Proving its watchmaking mastery once again, Breitling created the Transocean Chronograph 1461 as a standard for this kind of mechanism (note the name refers to the number of days in a four-year span). Driven by the self-winding mechanical Breitling Calibre 19, this watch boasts an intricate dial with a nod to vintage style.
Eternity on the Wrist: The Perpetual Calendar
The crowning jewel in the eyes of many haute horology collectors and connoisseurs is the perpetual calendar watch. This grand complication is manufactured by only a handful of watchmakers worldwide because of the unparalleled complexity of its mechanism. Like the semi-perpetual calendar, this category of watch needs adjustment only after years, but rather than every four years, it can accommodate a century’s worth of date changes. Consequently, the next year that most perpetual calendar watches will need adjustment is the year 2100 as it will not be a leap year because centurial years are only leap years if they are exactly divisible by 400.
Some perpetual calendar watches are even more complicated, capable of calculating hundreds of years’ worth of date idiosyncrasies. Currently, the world’s most complex perpetual calendar watch is the IWC Portugieser Perpetual Calendar, which diverges by just a single day every 577.5 years — an incredible achievement by any engineering standard. IWC have long been the champions of the perpetual calendar thanks to the company’s legendary watchmaker Kurt Klaus, who first developed the complex system for the Manufacture with the Da Vinci Perpetual Calendar introduced in 1985. Shocking the watchmaking world at the time, this timepiece only needed adjustment once every 122 years. Equipped with the manual-wind Calibre 52610, the modern Portugieser Perpetual Calendar offers a generous 7-day power reserve.