“Of course, watchmakers just love a perpetual calendar,” enthuses Stephane Widmer, technical office manager for Bovet. “I mean, here’s a complication, parts of which don’t move for hundreds of days and then which have to move precisely at one particular time on one particular day. It’s mechanically pure – and us watchmakers tend to be a bit square. Admittedly it’s not a very playful complication – you can’t press buttons and see something happen for the fun of it. That said, we do have customers who get together to sit and wait for midnight on a leap year to see the date flip over. The perpetual calendar inspires that kind of adulation.”
A perpetual calendar in progress, courtesy of A. Lange & Söhne.
Indeed, it may come down to a tie with a minute repeater, but the mechanical perpetual calendar is certainly one of the most complicated of complications – after all, it displays the date in a way that, unlike most watches, not only allows for the various number of days in different months, but also compensates for leap years, such that a perpetual calendar worn consistently from today won’t need resetting until 2100. By then, dear reader, you’ll be long gone but your watch will still be whirring on.
The movement of the earliest known perpetual calendar made by Thomas Mudge. The complexity is evident from its thickness, courtesy of Sotheby’s
The first perpetual calendar pocket watch was invented by Thomas Mudge in 1762, yet it wouldn’t be until 1925 when Patek Philippe produced the first perpetual calendar wristwatch. That’s how hard it is to miniaturise this complication, just so that its wearer isn’t thrown out of sync for a moment every four years.
“But that matters,” laughs Anthony De Haas, director of product development at A. Lange & Söhne. “The leap year indicator is so complex. It may be the only real difference between a perpetual calendar and an annual calendar [which can handle the variable lengths of each month], yet the former is typically twice the price of the latter. And a perpetual calendar just looks cool precisely because it looks complicated, with all those dials. It’s very ‘wow!’.”
The first perpetual calendar to be made in series, the Patek Philippe ref. 1526, courtesy of Christie’s.
It’s also very now. IWC’s 1985 Da Vinci perpetual calendar may, as De Haas argues, have helped the wider revival of mechanical watches in the immediate aftermath of the ‘Quartz crisis’. It is only in the last 10 years or so that interest in taking such an old complication forward has really found momentum. This is a good thing – up until recent times, perpetual calendars were (and some still are) so complex that they were all too easily sent haywire by even the most gentle mishandling.
Wind the setting too far forward and you’d likely need to move it through another 364 days to get back to where you wanted – such winding adding all the more wear and tear to an already fragile mechanism – or, alternatively, you’d be in for a long wait. Incredibly, in some examples you can even wind on the movement at the wrong time of day and break teeth off cogs. Setting such watches can be hellishly confounding.
A Patek Philippe advertisement from 1954 espousing the benefits of owning a ref. 2497, courtesy of PuristSPro.
“Even with design improvements people still find them difficult to adjust. I see a lot of perpetual calendars that aren’t set properly – the owner has left, say, the moon phase. It’s just a step too far for them,” concedes De Haas. “Really you just have to read the manual to use one just fine. But we don’t do that anymore do we? I’m the same as many men – if I get a new toy, I start by pressing all the buttons to see what they do. And that’s not a good idea with a perpetual calendar.”
Certainly, the complexity of this complication isn’t just about scale. It’s about energy. If a chronograph requires a lot of energy just to move those three extra hands, now imagine the energy demands of a watch whose entire mechanism needs to be constantly running, even while it appears to be doing not much at all. This requires minimal friction, minimal weight and whatever else can be done to conserve energy.
Getting up close on an Audemars Piguet QP salmon dial and open dial Royal Oak.
“The stupid thing about months is that some have 28 days, some 30, some 31, and then every few years one has 29. It’s not a great system, but somehow the watch has to progress its wheels to display these jumps, and to do that over really long time frames, especially with the leap years,” explains Walter Volpers, associate director of technics at IWC. Then, he adds, there’s the incredibly high tolerances required of the parts – which is one reason why there are so few perpetual calendars, since invariably they have to be handmade, automation still only allowing for much bigger tolerances.
“Get one tolerance off and the whole thing won’t work,” says Volpers, who says tolerances could likely be greatly improved by use of advanced micro-mechanical engineering out of Japan or China, if only that didn’t ruin the ‘Swiss Made’ image of the resulting watch. “This pressure on tolerances also means that to make a tougher watch – of the kind this should really be, so you can wear it actively – you need to compromise on diameter and thickness, but then you have a less elegant watch. And this is typically meant to be an elegant watch.”
A quintessential perpetual calendar from Patek Philippe, the ref. 3940.
It’s why such an esteemed watchmaker as Roger Smith has yet to go anywhere near a perpetual calendar wristwatch – at least, he hints, not yet – fitting the movement only into pocket watches. “I like a robust watch, and the fact is that the fragility of any watch, but the perpetual calendar especially, is a product of having to scale down something of a complexity that works perfectly well given the space, but much less well if it isn’t. And you do need to give the perpetual calendar space,” he explains. “When you hear of million pound perpetual calendars that only last a few months before needing attention, that suggests you also need a complete change of design approach.”
All of which begs the question, if perpetual calendars can not only be challenging to make, but even to own, what quite is their appeal? Michael Friedman, who holds the fantastic title of ‘head of complications’ at Audemars Piguet – makers of rods for its own back, and hence the RD2, the world’s thinnest self-winding perpetual calendar watch – gets philosophical on this question. If, he says, watches are so often celebrated for their precision in the moment, for their nowness, for splitting seconds, the perpetual calendar celebrates slow time. Indeed, the very name says it all: the perpetual calendar might as well be called the forever watch.
A slightly sportier perpetual calendar in the shape of a Royal Oak.
“I think it’s a real reminder of where you’ve been, where you are and where you’re heading,” says Friedman. “I think a movement that measures time over months and many years can only speak to something deeper than just being a great watch – it speaks to our evolution, to our observance of natural cycles and their impact on navigation, on agriculture, on the course of human development. The perpetual calendar links us back to pre-mechanical horology, to the measure of time as an aspect of astronomy. And in times when mechanical things are commonplace, it’s easy to forget what a pivotal innovation the perpetual calendar was – because it is very much a computational device.”
That’s apt because, says Friedman, Audemars Piguet’s more recent advances with its perpetual calendar movements – seeking to strip away literal layers of complexity, to make components multi-functional – have only been possible because computers of the silicon chipped kind have been available to do the necessary maths.
The wonderfully textured dial of an Audemars Piguet QP.
Indeed, the perpetual calendar is seeing its own evolution enjoy something of a Cambrian explosion. More recent perpetual calendar watches have taken steps towards greater user-friendliness, following the modern, consumer-focused idea that if something doesn’t work, the fault really lays in the design and not in the user. It’s why an A. Lange & Söhne perpetual calendar, for example, now has a single pusher that advances the entire mechanism by one day per push. Or why Ulysse Nardin made setting its perpetual calendar bi-directional, keeping a pusher for some functions.
Arguably, it’s telling that it’s the small, independent watchmakers, which have grown up over the last two decades, that are really pioneering new thinking about the perpetual calendar. Take Greubel Forsey’s QP piece that gets rid of the traditional pushers altogether. It makes everything adjustable using just the bi-directional crown, how one is used to setting most mechanical watches.
The inner workings of Greubel Forsey’s simplified perpetual calendar, courtesy of Greubel Forsey.
“All the pushers you usually find on a perpetual calendar just make setting it up challenging, create problems with regards to waterproofing, and so on. And when I worked in watch restoration, we regularly had calls from owners wanting to bring in their perpetual calendars because they were scared of setting them and getting in wrong. So, we knew we wanted to start from scratch with ours,” explains Stephen Forsey.
Not that this didn’t mean a steep learning curve. With the first prototype Greubel Forsey was fairly confident that it had nailed it. Then, much to its dismay, the team realised that there was still a way the watch could be badly mis-managed. So, it had to develop a second mechanism and, a few months and 16 more components later, the QP was finally ready. A. Lange & Söhne had a similar experience illustrative of just how the most minor hiccup can be massively magnified in a perpetual calendar.
The Lange 1 perpetual calendar tourbillon made to celebrate the 25th anniversary of the iconic model, courtesy of A. Lange & Söhne.
“There was a phase when we kept getting one particular model of perpetual calendar watch back into the workshop with owners telling us that it kept showing the wrong date, and we took these watches apart and just couldn’t find anything wrong with them,” recalls De Haas. It turns out that these pieces were all on a folding buckle strap, so they were being laid on their side at night; and that laying on their side meant a pusher placed at 10 o’clock came into contact with the table; and an insufficient resistance in the pusher meant that, well, it got inadvertently pushed. A. Lange & Söhne replaced the pusher with a flush, integrated variation on later models.
It just seems that perpetual calendars come with integrated headaches. So, when watchmaker Stephen McDonnell proposed making one with MB&F, brand owner Max Busser thought he was joking. “There’s a reason some dub them ‘boomerang’ watches,” he says, “because they go out of the workshop, and then a few months later come back into the workshop. They jam. Owners force the pushers and break them. But then Stephen had one of those simple ideas where you say ‘fuck, why didn’t I think of that?’”
MB&F’s first attempt at a perpetual calendar with the updated movement below with McDonnell’s brilliant upgrades. Movement shot courtesy of MB&F.
That idea is – as with Greubel Forsey’s watch, but in a different way – to effectively build a mechanical processor within the watch. This, in MB&F’s Legacy Machine – and now, thanks to the development of an innovative 3D gasket – amounts to a patented coding module of variably-sized cams which, on the 25th of every month, tells the movement what to do at the end of that month (ie, whether to reset at day 28, 30 or 31). Add in a retrograde system for the end of each month, greatly reducing the strain on the mechanics, and a clutch that prevents the kind of damage perpetual calendars are often subjected to by their owners, and the result is a major, convention-busting advance. It entirely replaces that big, flimsy lever...
“The fact is that the kind of perpetual calendar movement you get in, say, a Patek is more or less what you’d get in a 19th century pocket watch – all the date numbers are still bunched up on the display, because that’s a product of the mechanism, and the basic operation of the whole thing is around a big, flimsy lever, with all the work going in to limiting the movement of this lever,” laments McDonnell. “Really, to have a watch that can do what a perpetual calendar does is amazing. Very few people ever have one. And the cost of starting anew on the engineering, in what is after all a very small part of the industry, probably hasn’t been worth it for most traditional makers. But, you know, that doesn’t change the fact that the thinking behind the standard perpetual calendar has just been a bit crap.”
A perpetual calendar executed simply and with balance.
Now that, at last, is changing. Perhaps, indeed, what we are witnessing is the start of a process of reassessing all of the most hallowed movements in mechanical watchmaking, with the fact that they’ve been extant for centuries no longer regarded as sufficient reason not to re-think them altogether. “Not that that’s easy,” laughs McDonnell. “The solution in this case came quickly. But prototyping it was the most stressful thing I’ve ever lived through.”
Those lucky enough to own a perpetual calendar may be saying the same simply about setting theirs, even as they look to the stars, and watch the seasons change. They may know they have a small mechanical marvel on their wrists. But do they know where they put the book of instructions?