In 1884, Vacheron Constantin presented its first pocket watch with a perpetual calendar known to date. For more than a century, this mastery of astronomical indications has been confirmed in the Maison’s grand complication calibres. The Vacheron Constantin collections perpetuate this tradition in which technical sophistication vies with aesthetic elegance.
The vagaries of the Gregorian calendar have enabled watchmakers to exercise their genius in devising mechanical representations of these quirks. At Vacheron Constantin, this resolutely horological approach to astronomy was strongly expressed as early as the 19th century. Greatly appreciated by connoisseurs, it continues today in the Maison’s collections.
The perpetual calendar is one of the horological complications regarded by connoisseurs as masterpieces of mechanical engineering. This is due to their level of complexity, as well as because these calendar displays are a direct consequence of astronomical observations made since the first civilizations. For those who grasp its full depth, a watch with a perpetual calendar very quickly becomes a link with the cosmos – and one that is all the more symbolic in that it requires consummate watchmaking science to create.
The perpetual calendar is a mechanical solution to an astronomical problem. From ancient Egypt to Rome and Greece, and from astronomers to mathematicians and priests, the history of the calendar has mainly revolved around the question of fitting the lunar and solar calendars within a system of integers (whole numbers).
In 1582, Pope Gregory XIII reformed the Julian calendar used in Europe since its introduction by Julius Caesar in 46 BC and instated the Gregorian tropical solar calendar. Subsequently adopted over the centuries by the international community, it is currently the most widely used civil calendar. The reason for the reform was that the Julian calendar was drifting, so that the Easter feast day, linked to the spring equinox, was no longer in step with its ritual season.
The Julian calendar had 365 days, whereas the solar year or “tropical year” – meaning the time required for a complete revolution of the Earth around the Sun – lasts exactly 365 days, 5 hours, 48 minutes, 45 seconds, or 365.2421875 days. The Gregorian calendar compensates for this difference by adding a 29th day to February every four years. It provides a system that indicates the seasons accurately and runs from January 1st to December 31st in 365 days and 12 months. However, given its solar nature, its dates do not indicate moon phases.
The 12 months of the Gregorian calendar consist of 28, 30 and 31 days. Each year divisible by four is a leap year, apart for those divisible by 100, although there is an even exception to this exception: century years exactly divisible by 400 are nonetheless leap years. For example, the years 1700, 1800 and 1900 were not leap years, whereas the year 2000 was.
The only thing that owners of a perpetual calendar watch and their descendants will need to do is to adjust it at each turn of the century, unless the given century is divisible by 400.
For a long time, such peculiarities proved a problem for watchmakers seeking mechanisms capable of reproducing them without human intervention. The solution finally came from the invention of a component called a “cam”, a kind of mechanical memory generally based on a 48-month cycle. This disc has notches of different depths, each of which indicates a certain type of month with either 30 or 31 days.
The February satellite, which is on two levels, indicates months of 28 and 29 days. The deeper the groove, the shorter the month. The information provided by the cam is passed on via a feeler-spindle to a large yoke that activates the various displays.
The perpetual calendar is complex to adjust because it must be set according to a four year cycle, and four years must pass to ensure that it works perfectly – even if the four-year cycle is simulated on a machine.
The archives of Vacheron Constantin reveal a first perpetual calendar in 1884, integrated into a double sided yellow gold pocket watch, now part of the Maison’s private collection.
This was the beginning of a mechanical “epic” that would singularly take shape at the turn of the century. In 1900, the Maison set up a workshop exclusively dedicated to the assembly of watches with complications.
And orders did indeed flow in for complicated, even very complicated watches. The perpetual calendar was then combined with other technical feats such as in this 1905 pocket watch featuring a minute repeater, split-seconds chronograph and perpetual calendar with phases and age of the moon.
The months wheel makes a complete rotation every twelve months, the exterior of the cam indicates the 31-day months, the teeth the 30-day month and the February planetary wheel (which makes a complete rotation every four years) indicates whether the month has 28 or 29 days. This information is transmitted via the main lever to the date wheel.
The historical golden age of complications in Vacheron Constantin was on the horizon. It was to reach its full potential in the 1920s and 1930s, particularly with the astronomical pocket watch made in 1929 for King Fouad I of Egypt. This masterful timepiece combines a chronograph, a perpetual calendar, a minute repeater and a petite and grande sonnerie.
For much of the 20th century, Vacheron Constantin remained faithful to its classic and elegant approach to horological complications, which was applied to the perpetual calendar as a pocket watch until the 1980s.
These decades were thus marked by exceptional achievements, including the yellow gold hunter-type pocket watch acquired in 1948 by Count Guy du Boisrouvray, which offered a minute repeater striking on three hammers, alarm, split-seconds chronograph and perpetual calendar with moon phases. Elegance was particularly conveyed through models featuring impressive slenderness made possible by the thinness of their movement.
In 1955, Vacheron Constantin had already presented its manual-winding Calibre 1003, barely 1.64 mm thick and a major accomplishment.
Some 12 years later, the Maison made its presence felt in the automatic field with its Calibre 1120, measuring just 2.45 mm thick.
It is precisely this movement, skeletonised for the occasion that would serve as the basis for the first perpetual calendar (Calibre 1120 QP) proposed as an ultra-thin wristwatch by Vacheron Constantin in 1984.
Since then, the perpetual calendar has been part of the Maison’s Patrimony, Traditionnelle and Overseas collections, as well as being incorporated within Grand Complications movements, an immutable tradition at Vacheron Constantin.
In recent years, the Manufacture has distinguished itself by its models whose very complexity has become an art in its own right, such as the Tour de l’île and its 16 horological and astronomical complications created in 2005 to mark the Manufacture’s 250th anniversary.
That same year saw the launch of the Saint-Gervais watch equipped with the new Calibre 2250 featuring a perpetual calendar, a tourbillon and a 10-day power reserve – another world first.
More recently, in 2015, Reference 57260 and its 57 complications, a specially commissioned one-of-a-kind model, laid a new milestone in watchmaking history.
This was followed two years later by the Cabinotiers Celestia Astronomical Grande Complication 3600 watch, which once again pushed the limits of feasibility with its combined display of civil, solar and sidereal time.
All this was naturally complemented by a perpetual calendar with moon phases, a common denominator in the watchmaking world according to Vacheron Constantin.
In 2019, the Traditional Twin Beat perpetual calendar features an innovative mode of operation with two gear trains running at different rhythms: in moving from a first high frequency oscillator (5Hz or 36,000 vph) – synonymous with ultimate precision – to the second rate of 1.2Hz (8,640 vph), the watch switches to ‘resting’ mode, thereby serving to extend the power reserve to at least 65 days.
The accuracy of the calendar indications thus remains intact for more than two months, avoiding any improper handling of the calendar mechanism.
Finally, in a style that is both timeless and contemporary, the new Patrimony ultra-thin perpetual calendar adds its discreet elegance to the technical prowess of the 1120 QP calibre, by displaying moon phases and perpetual calendar on a sunburst midnight blue dial.