Watches in Depth - Minute Repeaters ¶
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In the realm of complications there are certain functions that surpass all others in terms of complexity. You have the tourbillon, the most common superfluous complication out there. You have the perpetual calendar, the mechanical calculator that computes the leap year cycle. You can have a myriad of lesser complications combined together. But for the true watch lover, nothing beats the king of haute-horlogerie – the mighty repeater complication, one of the most difficult mechanisms to execute and one of the single most expensive complications to purchase.
What is a repeater? It’s a watch that chimes the time, either passively without the wearer’s intervention (as in a sonnerie) or by activating a mechanism through a slide or button (the repeater). Sounds simple enough. But to create a mechanical chime that can compute the current hours and minutes, and ring them clearly and beautifully, is a staggeringly difficult task. As a result repeaters and sonneries can be some of the most expensive timekeeping devices you can buy and strap to your wrist.
Repeaters began as a way of checking the time in the dark, in the days long before the introduction of luminescent dials. The watch “repeats” the time back to the wearer with a series of chimes struck on internal gongs. Normally there are two gongs: one low pitch, one high pitch. Hours are indicated by a low tone, quarter hours by a high tone and low tone alternating, and minutes by a high tone. So, if the watch struck “tong tong tong, ting-tong, ting ting ting” it would be 3 hours, 1 quarter (15 minutes) and three minutes past the quarter – 3.18. Repeaters have existed for centuries, developed in watch format in the late 1600s by two inventors simultaneously (Englishmen Edward Barlow and Daniel Quare).
That pattern of indicating hours, quarters and minutes is the minute-repeater. It can chime to within the minute indicated on the dial. A five-minute-repeater can chime to the nearest 5-minute interval, while a quarter-repeater will only chime the hours and quarters. A half-quarter repeater will indicate the halfway point between each quarter (7 ½ minutes). A simple repeater will chime only the hours. Nowadays the most common (if you can call it such) repeater is the minute repeater; it is also the most difficult to execute.
The sonnerie (sometimes called a “clock watch”) is a function that will be familiar to anyone who has had a grandfather clock – it passively chimes the quarter hours (15 minutes) and the hours. You may have the Westminster chime added as well (think Big Ben). A grand sonnerie will chime the hours followed by the quarters at each quarter, so at 4.15 it will strike four low tones followed by one ting-tong for the quarter. The hour is indicated at each quarter. A petite sonnerie strikes the hours at the top of the hour only, with only the dual tone at the quarters. In most modern sonnerie watches there will be a selector slide that will allow the wearer to select grand, petite, or no sonnerie. The most complicated repeater mechanism will combine a minute repeater with a sonnerie. Sonneries are particularly complex because they require a constant power supply from the movement to function, either drawing from a second mainspring or feeding off the mainspring of the movement. A repeater normally has a spring mechanism integrated into the activating slide so it doesn’t draw any extra power.
So how does this complication function? This is where the beauty and complexity of the repeater shows through. First, the watch needs to be able to determine the current exact time to correctly strike what is indicated on the dial. To accomplish this there is a delicate series of star and snail-armed gears connected to the pinions of the hour and minute hands under the dial. Each tooth represents either an hour, quarter or minute; a set of levers follows the wheels as they turn and constantly indicate the current time. These act upon a series of levers that control the striking mechanism. This striking “computer” has several snail-shell shaped gears that determine the number of strikes and what gong (high or low) to use.
When the slide on the side of the case is pushed a tiny spring is wound. This spring has just enough tension to run the repeater once, each push of the slide winds it up again. There is a small blocker attached to the slide called an all-or-nothing piece that will only allow the repeater to start if the slide is fully pushed (a lazy push will not activate it at all, this corrected a problem with early models that wouldn’t chime the complete repetition if the slide was half-heartedly moved). The spring activates the mechanism, which determines the current time based on the position of the levers and snail gears and then translates that into a series of strikes from two hammers. The chime is a pair of hammers that strike a round wire gong that runs the perimeter of the case around the movement.
(Courtesy of Hodinkee.com, a vintage Patek Philippe Minute Repeater)
Creating a clear and loud chime is a challenge for any watchmaker designing a repeater. The delicacy of the parts, the lack of space, and the minimal power available to move the hammers all conspire against having a prominent chime. Additionally the material of the case has a significant effect on the sound. Because it is such an expensive complication, many minute repeaters are cased in gold or platinum. However, because of the density of these precious metals, the sound is deadened by the case. The best sounding repeaters are traditionally steel cased, and many watchmakers choose to use steel for this reason. Hence you can see a repeating watch going for several hundred thousand dollars with a stainless steel case. Some newer designs are making use of the good acoustic properties of sapphire crystal by attaching the gongs directly to the front crystal of the watch, while other companies (like Hublot, for example) are using high tech composite materials that enhance the acoustics of the chime. Even then, the loudest and clearest minute repeaters are still quite unobtrusive, softly chiming the time without being annoyingly loud. Think something along the lines of a wind-up music box and you have a good idea of what they sound like.
Minute repeaters and sonneries, while incredibly intricate on their own, are often combined with other haute-complications to create spectacular watches of staggering complexity. The traditional “triple-complication” is a minute repeater with a chronograph and perpetual calendar, this having been a popular combination in pocket watches for over a hundred years. Today some of the most complex watches in existence have minute repeater mechanisms on top of tourbillons, perpetual calendars, split-seconds chronographs, celestial displays, equations of time… you name it, and it’s been combined into a single design. Because it is a subtle complication, only indicated from the outside by the presence of a slide on the side of the case, the minute repeater is a classical watch complication for true aficionados who are willing to spend obscene amounts of money for pure complexity without any flashiness (or the complication-fad-du-jour). Anyone can spot a tourbillon when they are spinning around on the dial, but a minute repeater is a rare and low-key beast that will only reveal itself when you activate it and let loose a string of delicate chimes.
Minute repeaters are rarefied territory, even for high complications. While most major companies will produce at least one tourbillon model, only the top watchmaking houses are capable of producing minute repeaters and sonneries. As such they are some of the most expensive wrist (and pocket) watches ever crafted. Handling a minute repeater is a once in a lifetime experience.