The beauty of a mechanical watch often cited by those who love them is the human interaction they require—winding, setting, operating a chronograph—but there is one kind of mechanical watch that is celebrated for its mechanical independence: the perpetual calendar.
Far from lesser complications that merely rely on gear reductions and clutches to perform functions, the perpetual calendar watch is endowed with a true mechanical memory, a sort of artificial intelligence that, as long as it is kept running, will tell you the correct day and date for generations.
Our Cursed Calendar
If you check your watch on December 1st and find that it still tells you it’s November 31st, blame the ancient Romans. The months themselves, January, named for their god Janus, March for Mars, and so on, are evidence of that fallen empire’s bearing on our modern lives. The earliest Roman calendar followed a lunar cycle with only ten months, which is why September (“seventh”) through December (“tenth”) now doesn’t make sense for those who paid attention in Latin class. A later calendar added months to honor the Caesar dynasty – Augustus and Julius— and those months had to have the most days (31), as did October (Octavius).
The Roman calendar came close to adhering to the sun’s travel across the sky, but those imperially decreed 31-day months became the curse of future horologists.
Most watches that simply tell the time and date are created with the longer months in mind. Their geared date wheels count off 31 24-hour cycles before starting all over again. To build a watch movement that can account for those shorter months that come around five times a year requires the addition of a cam wheel with lobes and notches that activate the date wheel to advance to “1” after the 30th of, say, November.
The annual calendar is a handy complication–and definitely a smart watch–but it still needs to be manually corrected for that oddball month February with its 28 days.
And then there is Leap Year. This year, 2016, is one of them.
Like the longer months of the Roman calendar, Leap Year also finds its roots in a decree, but a religious one instead of a political one. In order to ensure that Easter fell as close as possible to the spring equinox every year, Pope Gregory declared that every fourth February would get an extra day to keep the calendar synchronized to the seasons.
This “Gregorian” calendar compensates for the fact that a 365-day year is six hours shorter than a true solar year by resetting it every four years. But while the Roman and Gregorian calendars presented daunting cycles, watchmakers rose to the challenge and in the late 18th century, such horological luminaries as Thomas Mudge and Abraham-Louis Breguet created pocket watches that solved the problems presented by an imperfect calendar.
In the 1920s, the perpetual calendar first found it’s way into a wristwatch, and ever since the complication has been a coveted addition to any collection.
The perpetual calendar watch is, as its name suggests, autonomous in its date calculations, even in Leap Years, thanks to a “mechanical memory” of 1,461 days. At its heart is a program wheel that, once set in motion, triggers correct date changes in near perpetuity. Just keep the watch wound or there’s a considerable amount of setup you’ll have to do to get it back in synch. Perpetual calendars show off their prowess by displaying the day, date, month, time and often moonphase displays and often add an indication of the current position in the four-year
Leap Year cycle.
How the watches display this prodigious data varies wildly as evidenced by the breadth of offerings from top timepiece companies, old and new.
The name Breguet has been on watches made for Napoleon and Marie Antoinette; the brand’s founder was behind most of watchmaking’s milestones during his lifetime. His company’s legacy continued long after his death, including the distinction of building one of the first perpetual calendar wristwatches in the 1920s. The current Classique 5327 carries forward many of the brand’s historical aesthetic cues, with blued hands named for Breguet himself, a guilloché dial and distinctive off-center displays for month, day, date, moonphase and leap year. The 5327 is a classic piece but it is also shows how Breguet has kept up with the times, with a silicon hairspring that is immune to the detrimental effects of magnetism.
No listing of perpetual calendar watches is complete without a Patek Philippe. The brand was one of the first to present a perpetual wristwatch and they’ve arguably been the gold (or sometimes platinum) standard ever since. The reference 5140 is one of the most iconic timepieces in Patek Philippe’s current collection. The Geneva company’s legacy alone is enough to make this watch significant, but its classic subdial arrangement of all relevant calendar details is reminiscent of many Patek Philippe perpetual calendars dating back to the turn of the last century. When you turn it over and gaze on the exquisitely decorated movement and you can see why Patek Philippe sits at the top of the heap.
Another heavyweight name in watch complications is Audemars Piguet. In fact, Jules Audemars built a perpetual calendar pocket watch in 1875 as his school project before he went on to found his own company and in the mid-1950s. Audemars Piguet became the first to include a leap year indication on a perpetual calendar wristwatch.
The latest in this storied lineage is the Royal Oak Perpetual Calendar in yellow gold, a watch first shown at this January’s Salon International de la Haute Horlogerie in Geneva. The calibre 5134 inside the watch is an evolution of an earlier Audemars Piguet movement, increased in size to keep proportion with the watch’s 41mm sporty Royal Oak case. The watch maintains a svelte 4.31mm stack height, remarkable for such a complicated movement.
Speaking of thin perpetuals, Vacheron Constantin also debuted a new quantième perpetuel at this past SIHH as part of its refreshed Overseas collection. The Overseas Ultra-Thin Perpetual Calendar bears the same angular case, crenelated bezel and integrated bracelet that are hallmarks of this luxury sports watch family, but the series of subdials upfront show all the relevant calendar information. Despite being a self-winding timepiece, the Overseas perpetual comes in only a hair over 8mm high. Ultra-thin indeed.
A. Lange & Söhne has also built its share of perpetual calendars since the German brand’s rebirth in 1994. This January, it added the complication to its Datograph, already a modern icon. The flyback chronograph with an oversized date display seemingly could not have gotten more complicated, but Lange not only fitted it with a perpetual calendar that makes use of the chronograph subdials to legibly show the calendar information, but also threw in a tourbillon for good measure. The watch was one of the undisputed stars of the SIHH 2016.
Look for more perpetual calendars on iwmagazine.com and in the upcoming issue of iW Magazine.