The mechanical complexity isn’t the only problem that needs solving. In fact, it’s not even the main problem that needs solving. A calendar complication as readable as a newspaper at night can be as clever as it likes—but if it doesn’t make clear, obvious sense, it may as well not exist.
So let me take you through the details of this midnight blue fumé dial. We’ll start with something familiar, the Gregorian date at six o’clock, right at the bottom of the dial, below the hacking seconds subdial. Pretty straightforward so far. Then, in the crescent window to the left, a retrograde lunar months display, tracking all 12 lunar months.
On the right, there’s another crescent retrograde display that reads not only the lunar day, but also the phase of the moon, which sneaks in behind the dial either side of the full moon that marks the middle of the month. Then, right up top you get the zodiac symbol for the relevant year.
Now, what about that extra thirteenth month every two to three years? That’s the toughest challenge. It’s like the leap year, a bit untameable. But H. Moser & Cie. have overcome this hurdle with an additional display right beneath the year indicator. It tells you when there’s an extra month in that year. But that extra month doesn’t always come in at the same place every year. It can be inserted anywhere from the second to the eleventh month, and then gets the same number of days as the previous month. So the embolismic month, as it’s known, is displayed with the number of the month it’s inserted into right below the year.
If that wasn’t clever enough, what’s most fundamentally impressive about this watch is that, while a perpetual calendar operates on a four-year loop, the Endeavour Chinese Calendar has to keep count all the way up to 12 years, because of the zodiac cycle. That means this watch only needs adjusting once every 12 years, which is incredible considering it’s juggling two calendars, the sun and the moon.