After delving into the history and implementation of some of the more commonly seen complications out there, today we are taking a whistle-stop tour of some of the more unusual ones. Many of these complications are found only in the most exclusive and highest-end of mechanical movements, but a few can still be found in watches that come in at relatively affordable price-points.
Kicking things off are two of the more useful complications which we haven’t covered so far — the annual*and perpetual calendar, which are extensions of the date complication. A simple date complication shows the date within the current month and in its most basic form uses a disc with numbers from 1-31 advancing one notch every 24 hours. There is no knowledge of how many days in each month, so if a month has fewer than 31 days, then you as the wearer are required to advance the date manually to the first of the new month. Annual calendars and perpetual calendars are both extensions of this, but feature inbuilt knowledge of how long each month is.
IWC Portugieser Annual Calendar

An annual calendar complication is able to keep track of the month as well as the date, while also recognizing that some months are shorter than others. At the end of April, for example, the date will switch over from the 30th to the 1st of May — skipping the 31. A perpetual calendar takes this one step further and also allows for leap years. Where an annual calendar will assume 28 days in every February, the perpetual calendar allows for 29 days in February once every four years. Because of the need to correctly set the current date, month (and potentially year), these watches will normally also show that information on the dial, and the use of a winder is often encouraged to avoid time and effort resetting each time the watch dies.

Audemars Piguet Jules Audemars Equation of Time complication

Moving on to a display of information that’s a little less valuable, a watch that contains an equation of time complication shows the difference between solar time and “mean” solar time. We generally understand that a day is the time it takes for the earth to rotate so that the sun appears at the exact same point in the sky. On average, this period is 24 hours, and that is the basis of time as we measure it. Because the earth’s orbit is not perfectly circular, and therefore the earth is sometimes closer to the sun than at other times, a true solar day can be up to 29 seconds longer or 21 seconds shorter than your average 24 hours. The current difference between solar and mean time is shown on the dial of an equation of time watch, though what you might actually do with this information is anyone’s guess.
Have you ever wanted to know the relative positions of Mercury, Venus, Earth, Mars, Jupiter, and Saturn around the sun? And did you specifically want this information to be shown on your wristwatch? With a planetarium complication from Christiaan Van Der Klaauw, you can have exactly that, and it’s all based on a humble ETA 2824-2. The Dutch brand also collaborated with Van Cleef and Arpels to create the stunning Complication Poétique Midnight Planetarium. It may not be easy to spot at first, but the time of day in 24 hour format is also represented by a shooting star.

Let’s move on to something more common and certainly more useful — the power reserve. This complication is more often seen on manual wind watches rather than automatics, but it can be helpful in both. Essentially, the display lets the wearer know the relative amount of “power” stored in the mainspring, and with that information the wearer can decide whether it’s time to give it a few extra winds, or to get up and go for a walk. Jaeger-LeCoultre’s Powermatic Calibre 481 was the first production wristwatch to feature a power reserve indicator, and that information has made its way onto many dials in many different forms ever since.
MeisterSinger Circularis Power Reserve

In it most basic form the power reserve indicator is a train of gears connected to the ratchet wheel and teeth of the mainspring barrel. As the mainspring is wound, or as the power stored in the barrel is released over time, the power reserve indicator moves accordingly. More complex solutions involve the use of a threaded cone and following arm, but the input from the two forces to show an increase or decrease in the power reserve is largely the same. While the power reserve indicator is most often incorporated into the dial display, this is sometimes hidden away on the back of the watch.
A dead-beat seconds complications takes the many beats-per-second of a mechanical watch and through some mechanical trickery — explained in some detail here*— displays it to the wearer as one tick per second. This complication was used by both Omega and Rolex in the 1950s and ‘60s, but it never really gained much popularity. The sweeping motion of a mechanical watch is now seen as a big attraction to many watch fans and it’s an obvious distinction between mechanical and quartz watches, but there are watchmakers today still playing with this complication.

JLC Geophysic True Second

Going from a complication that essentially masks the fast-paced heartbeat of the mechanical movement to one that proudly shows it in a jarring and aggressive manner, we haver the foudroyante, or jumping/flying seconds, and it’s a mesmerizing complication. Originally developed to satisfy the need for precise timing in sporting events and most commonly seen in high-end rattrapante chronographs, the foudroyante generally features a sub-dial where one revolution of the hand represents a single second. The individual beats of the movement are marked out on the dial and the seconds hand jumps from one marker to the next at lightning pace (“foudre” is the French word for lightning). If you’ve never seen one, I recommend a quick sojourn to YouTube to check it out.

The tourbillon was patented by Abraham-Louis Breguet and intended* to counteract the effects of gravity where a pocket watch would have spent a lot of time sitting mainly in a single position. The escapement and balance wheel rotate within the tourbillon cage to average out any positional errors. Because of the greater movement and wider range of positions that a wristwatch is subject to, a tourbillon is much less useful in practice, yet it remains highly prized. Double- and triple-axis tourbillons exist to even further reduce any positional effects (and to look even more impressive).
For those who live and work by the sea, keeping track of the tides is important. High and low tides are each in the ballpark of half a lunar day apart, or 12 hours and 25.2 minutes to add a more precise figure to it. Watches like the Sinn 240 St GZ take the simple route to measure this and incorporate a tide display, letting the wearer rotate the bezel to set the last known tide, and the markings will then give an indication of the next. However, a more elegant and expensive solution is to incorporate additional gearing into the movement to give an accurate, running display in a similar way to the moonphase complication. Christiaan Van Der Klaauw prefers this method in their Real Moon Tides complication, and their execution couples it with a charming raising and lowering of the tides through a dial aperture.

Christiaan Van Der Klaauw Real Moon Tides

Repeaters were designed as a way to tell the time in a situation wear one couldn’t reliably read it on a dial. What’s cool about repeaters is that the mechanism can be actuated on demand. Usually, a lever or slide on the side of the watch is actioned, and that provides power to — and kicks into gear — the repeater mechanism. The time is chimed out with varying level of detail depending on whether the given watch is an hour, quarter, or minute repeater, with each unit taking on a distinguishable tone. The complexities involved in including such work within a wristwatch make the repeater one of the most revered complications. As the hour and minute hands travel around the dial during normal usage, a “snail” for each of hour, quarter, and minute (each with the appropriate numbers of steps) is rotated in increments. When the repeater is called upon, the time is read from these snails and the number of chimes for each unit is associated to current position of its snail. This cursory introduction in no way does the complexity and craftsmanship of the complication justice. Suffice to say that the price tag for a watch with any kind of chiming complication, save for the humble alarm, is suitably high.
Patek minute repeater made for Ralph Teetor, circa 1925

Quite how much use any of the above really are is perhaps less clear — even more so for the many other complications not even mentioned here. Still, there is little doubt that the complexity, ingenuity, and artistry behind some of these more extreme complications represent some of the fundamental reasons why we love watches and horology in general.

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