Review: H. Moser & Cie. Endeavour Perpetual Calendar

I’ll get right to it: this is perhaps the cleverest watch I have ever seen. No exaggeration. There are more complicated, more technically advanced, more expensive watches out there, but for sheer engineering brilliance, this one takes the crown. Welcome to the H. Moser & Cie. Endeavour Perpetual Calendar.

To fully appreciate what H. Moser and Cie have done here, it pays to take a look at the tradition of the perpetual calendar complication—and indeed, the calendar itself. It would be nice if, like any other metric unit, time could be split into a uniform decimal system—but that’s far from the case.

Historically, calendars have always been based around some kind of astronomical passage, such as the cycles of the sun and the moon, and the subsequent passing of the seasons. Early Roman calendars were actually broken into ten months, following the phases of the moon, with the last month, February, shorter to keep the months correctly synchronised.

Rather embarrassingly for an empire the size of the Romans’, this system had drifted so wildly that January had fallen into the middle of autumn. So, the senate introduced a new month, July, named after the current emperor, Julius Caesar. Then came August, named after Julius’ grandnephew, Augustus, and an extra day was added to both.

The last thing the Romans did for the calendar was to introduce the leap year. One orbit of the Earth around the Sun is 365 and a quarter days, and so every four years another day was added to compensate. Although, to be precise, the length of a year is actually 365 days, 6 hours, 9 minutes and 9 seconds, slightly more than a quarter, so it was also decreed that the leap year every 100 years be skipped. But this still wasn’t accurate enough for Pope Gregory XIII, who noted that Easter was drifting from the spring equinox, and so he duly added a leap year back on to every 400th year.

This mess is the headache watchmakers have had to work with in creating the perpetual calendar complication. Irregularly varying months is one problem, but irregularly varying years is another thing altogether. A perpetual calendar needs to account for precisely 1,461 days to work properly.

Not so much of a problem inside a roomy clock, but squeezing all this into a watch is, as you can imagine, something of a challenge, one first met by Englishman Thomas Mudge in 1762. The watch, incredibly, survives to this day, and it’s unrecognisable by modern standards, adopting multiple rotating discs with which to display the various elements of the calendar.

Jump ahead to the first ever perpetual calendar wristwatch, a 1925 Patek Philippe, and the complication is shrunk even further. It had taken Patek Philippe 25 years to perfect the perpetual calendar, even within a pocket watch, over a century after Mudge’s. Patek Philippe’s wristwatch actually used a lady’s pendant watch movement developed several decades before, the wristwatch not quite yet adopted into men’s fashion.

What that watch gave us was the contemporary perpetual calendar layout, days and months indicated by hands on sub dials. Breguet followed in 1936 with the first perpetual calendar movement built specifically for a watch, and IWC some decades later in 1985 with a perpetual calendar movement that could be adjusted just through the crown, and not with multiple hidden pushers. So, what has H. Moser & Cie. done, after all these years, to revolutionise the perpetual calendar further?

What is immediately apparent with H. Moser & Cie.’s Endeavour Perpetual Calendar is that it looks nothing at all like a perpetual calendar. You’ve got hours, you’ve minutes, you’ve got seconds, there’s a date and there’s a power reserve indicator—the in-house calibre HMC 341 is hand-wound after all—and that’s your lot.

If you’re familiar with perpetual calendars from the likes of Patek Philippe and Breguet, you’ll know that spartan is one thing they’re not. Yet here the H. Moser & Cie. could quite easily pass as a simple watch. But it’s not. It’s really, really not.

Think about the calendar for a minute, about the butchery that turned it into the mess it is today: it boils down to irregular months and irregular years, at least, that’s about the gist of it. You know those little brass paperweights with the disks you can turn to work out the date? All you need to use them is the year and the month. If you can figure those out, then you’ll be able to figure out the date. So, that’s what H. Moser & Cie. has done.

Look closely at the centre of the dial and you’ll spy a stubby little hand sprouting out from underneath the hours and minutes. That’s your month hand. Makes sense—twelve hours, twelve months. Point the hand at the corresponding hour, January starting at one and so on, and that’s the month set.

How about the year, or rather, the leap year? With one out of every four years being a day longer—except that one pesky leap year every 100 years that’s skipped, the next being the year 2100, watchmakers can do nothing about that—it’s just the fourth year that’s different, and so it’s as simple as telling the Endeavour Perpetual Calendar where in that four-year cycle you are. Flip the watch over, press the hidden pusher, and watch the leap year disk rotate until it’s correctly aligned.

All that remains to do is to set the date in the normal way, and then it’s complete; every passing month will display the correct number of days, including on leap years, switching to the next on cue.

But it gets even better still. The big bugbear with perpetual calendars has always been the complexity of resetting it when you’ve gone too far. With a classic perpetual calendar, you have to cycle through the hidden pushers until the date or month comes back around, and with IWC’s crown-only perpetual calendar, you have to let it run down and wait for time to catch up—but with this, you simply wind the crown backwards. It’s so simple, so clever. No fuss. I honestly can’t believe it’s never been done before.

The simplicity and logic of this watch, after being accustomed to a traditional perpetual calendar watch for so long, is like a slap in the face. It’s like finding out you’ve been doing a simple task like walking wrong all these years. You blink a bit, taking in this new information as everything you thought you knew crumbles around you. It’s this kind of ingenuity that we live for, moments that stun us into silence—and this just might be the best of all of them.

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