Functions + Techniques: The Perpetual Calendar

If you were to list the complications that form the pinnacle of watchmaking, you’d be remiss to not include the mighty perpetual calendar. The idea of a calendar that can keep track of the changing length of months and leap years does not inherently sound all that complex when speaking to those without any background knowledge in the watch category, but anyone with even a vague understanding of mechanical watchmaking understands the level of complex micro-engineering required to make this a reality in a wristwatch. There’s good reason that so few makers have a perpetual calendar in their watch collections, and even with refinements in automated manufacturing capability, there’s little in the way of “entry level” perpetuals in the market to this day.

The almighty question, as it often is, is where did it all start, and how does it all work. The former is an element that we’re about to dive into, whereas the latter we’ll skim the surface. Simply put, at a technical level, a perpetual calendar is effectively a big game of gearing and levers, and unlike a chronograph, a remontoire, or a deadbeat seconds complication, the mechanics of a perpetual calendar are a little less glamorous when it comes to how they operate. They can be beautifully finished and a treat to look at through an exhibition caseback, mind you, but the technical explanations are best left for watchmaking textbooks.

In the Beginning

 Like many complications, the beginnings of the perpetual calendar go back centuries. No, this is not a new innovation, nor is it one that took modern advancement in production capability to turn into a reality. Like many watchmaking accomplishments, the Brits own this one. Thomas Mudge was a pioneer of British watchmaking, and his very first perpetual calendar pocket watch was completed in 1792, and presently resides safe and sound in the British Museum. For a bit of context, Mudge was a watchmaker in the era whose work was commissioned by King George III. Though he claims rank as first creator of a perpetual calendar, his notoriety in watchmaking comes from a smaller innovation that changed the face of watchmaking forever—the creation of the lever escapement. The lever escapement as Mudge created evolved into the “Swiss lever escapement” or anchor escapement, over time, but its influence remains present in the industry to this day.

What’s surprising in some respects is the gap from this first perpetual to the next. Based on what little information is out there, it wasn’t until over 100 years later that the next evolution of the perpetual calendar surfaced. In 1889 Patek Philippe filed a patent for a perpetual calendar mechanism, which was eventually deployed in pocket watches and pendant watches, though the specific details of what and when remain scarce to this day. We do know that Patek completed a wristwatch on commission for an American collector named Thomas Emery in 1925, using one of its pendant watch calibers.

It’s a bit surprising considering this early phase of innovation, but when it comes to the first perpetual calendar wristwatch with a movement specifically designed for use in a wristwatch, that title doesn’t go to Patek. It is instead the Breguet 4244 that holds this title—a wristwatch that was produced in 1929 and sold in 1934 for a hefty (for the time) 11,000CHF. When the piece went to auction in 2011, its hammer price came in north of 400,000CHF, as one would expect from such a historically significant piece.

From this initial sale, the next big change came with actual series production. In 1941 Patek Philippe came to market with a pair of perpetual calendars (one with a chronograph attached) in the form of reference 1526 and 1518. In both configurations, the design codes we often see today were already present—a day and month window at 12 o’clock, and a pointer date sundial at six. Over the course of 12 years, roughly 210 of the reference 1526 were produced before being replaced by the larger 37.6mm Calatrava cased reference 1527. This was seen as a pretty big step up from the original reference’s 34mm dimensions.

While the evolution carried on through the decades with Patek Philippe and others, we’re going to gloss past these relatively inconsequential changes. Instead, it’s time to skip ahead to the most surprising time to have significant advancement in haute horlogerie—the 1980s.

Unexpected Advancements

 The year was 1985, and the name was Kurt Klaus. Sound familiar? This was right in the thick of the Quartz crisis, and brands like IWC were fishing for ways to keep mechanical watchmaking alive. Starting in the mid 70s Klaus had been developing calendar modules for pocket watches, but he eventually got the go-ahead to start building a perpetual calendar wristwatch. Given the fragility of the market, it had to be as simple as possible to put into standard production, and it couldn’t be astronomically expensive either. With that in mind, Klaus set to building IWC’s first perpetual calendar wristwatch using the Valjoux 7750 automatic chronograph as its base. Where things get interesting is in the design of its setting mechanism. The standard process for perpetual calendars prior to this was to have hidden correctors around the case in order to separately advance the various elements of the calendar. In the case of this new IWC, all setting was completed via the crown—a detail that has since been making its way through a handful of brands to present day. The prototypes of the IWC’s perpetual calendar were displayed under the name Da Vinci, and were shown in Basel in April of 1985. By November of that year, the first 500 examples had been sold, and the direction of IWC began evolving into the brand we know and love today.

Thirty years later, the luxury watch market was a different beast altogether, however elements of Klaus’ logic path were further expanded upon in a completely different direction. This time it was Greubel Forsey’s turn to change the game, with the QP À Équation. Aside from adding additional functions to the equation, the big advancement here was in the “idiotproofing” of the perpetual calendar setting process. Unlike any perpetual calendar to come before or after, the QP calendar could be adjusted, advanced, and set at any time of day and in any direction. At any point prior, setting a perpetual calendar was a touchy process, meant to be unidirectional, and certainly not an adjustment to make anywhere near a midnight date change.

Now that we’ve done a surface level pass at the progression of the perpetual calendar, it’s time for a look at some of the more notable references in the category.

Bvlgari Octo Finissimo Perpetual Calendar

Kicking things off with the new “one to beat” in many respects, the new Octo Finissimo Perpetual now holds the record as the world’s thinnest perpetual calendar on the market. It ousted the recently launched Royal Oak Ultrathin Perpetual by a small margin, coming in at a shocking 2.75mm thick, and is just one of several record breaking Bvlgari watches to launch in the last handful of years. If you’re more interested in modern design rather than the classics, this thing is a no brainer.

MB&F Legacy Machine Perpetual

 One of MB&F’s most complicated watches ever made, the Legacy Machine Perpetual’s claim to fame rests not only in its unique design and fantastic finishing. The perpetual calendar uses a split escapement, where the balance wheel is a significant distance from the escapement. This requires an increased level of precision, especially in the construction of its balance staff, to ensure that this separation isn’t able to create any sort of imbalance. Having the balance wheel front and center on the “dial side” of this LM is the perfect bit of outside the box design to tie its openworked floating sundial construction together.

Patek Philippe 5320G

 From contemporary to classic we go, as this list couldn’t be complete without a modern Patek perpetual. The 5320’s dial layout carries all of the hallmarks of the references that preceded it, though with a little bit of a twist. Its crisp white SuperLuminova-filled indices resting above its cream lacquer dial give the modern reference an oddly tool-like aesthetic that border on pilot watch vibes. At 40mm in diameter it’s also large enough to serve as more than only dress watch duty.

F.P. Journe Octa Quantième Perpétuel Black Label

 After dabbling in both the classic and contemporary classes of perpetual calendars, the F.P. Journe Octa Quantième Perpétuel enters the conversation with the intent of blurring those lines entirely. In terms of movement finishing and case design, this watch obviously has traditional roots, however both its dial and functions are anything but traditional. It’s one of very few to use a dual disc date complication, but what’s more impressive is the timing of the instantaneous jump of ALL calendar elements at midnight. During R&D, Journe invested in high-speed video capture equipment in order to properly test and time these things. OCD? Perhaps, but totally worth it and worthy of appreciation.

Audemars Piguet Royal Oak Perpetual Calendar

 Can you go wrong with an AP perpetual calendar of any sort? No, and especially not when its a perpetual calendar variant of the most iconic Audemars Piguet watch ever made. The Royal Oak Perpetual Calendar is a modern classic in an extremely easy-to-wear 41mm case size. The “stainless steel integrated sports watch with blue dial” craze remains as out of control as ever, and there’s really no better way to beat the competition than to tick all of those boxes with one of the industry’s most desirable complications.

Blancpain Le Brassus Perpetual Calendar Chronograph Limited Edition

 Icons, legends, and classics are great, but not every perpetual calendar needs to be any of the above to be worthy of consideration. Most of you didn’t even know this watch existed, and some of you likely didn’t even know that there was a perpetual in the recent Blancpain catalog. This platinum cased perpetual chronograph was a limited run of only 100 pieces from around 2007, but that’s not the only thing that makes it special. Though it trades for relatively modest secondary market prices, it’s one of very few perpetuals that actually offers a split-seconds chronograph indication. This is bordering on grand complication territory, and in a platinum case its $34k sticker price feels like an absolute bargain.