I was recently watching a video online where one of the members of the discussion wasn’t sure which complication that Vacheron Constantin was known for. In truth, Vacheron Constantin put made a petite sonnerie, grande sonnerie and minute repeater into a pocket watch in 1817 – that’s 22 years before Patek Philippe actually opened it’s doors. Vacheron is ultimately a master of pretty much every complication out there, given the company’s history – but my favourite is the striking watch. The only forgiving point I’d make about the aforementioned video contributor is that not many of us get to experience such a timepiece – they command quite a sum….

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THE ORIGIN OF STRIKING MECHANISMS

Clock towers were a central to a community that would announce the time to the local residents the time of day. This was useful to the community for a variety of reasons, such as local work schedules or calls to prayer. While early clocks would manually require a person to “ring the bells” this then became an automated process built into the mechanism of the clock. 12 hour striking would chime the bells or gongs once at 1am, two at 2am and so forth up until twelve times at 12pm before resetting back to one chime at 1pm. The variation of 24 hour striking would strike thirteen times for 1pm – but the standard became the 12 hour strike across Europe first. Sometimes in early clocks there was no dial on the clock, so the sonic annoucement of time was the main way of understanding what time it was.

Many striking clocks also would play a sequence of chimes at the quarter hour. The most common of these was Westminster Quarters (as featured on Big Ben in London), but other chimes exist such as Whittington Chimes, St. Michael’s Chimes and Winchester Chimes. The use of striking mechanisms in clocks would allow the sound of the time to resonate within halls and the home.

Finally, within small timepieces such as a pocket watch the striking mechanisms would allow the wearer to know the time in the dark, such as the theatre and could be thought of as early luminescence. Nowadays we have little practical use for striking mechanisms (other than wrist watch alarms such as in the Jaeger-LeCoultre Memovox line of watches). Miniaturisation of these mechanical marvels is now reserved for the most expensive watches as a demonstration of technical excellence.

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REPEATING MECHANISMS

Repeating watches usually allow the striking mechanism to chime either on demand. The types of mechanism are as follows:

Half-Quarter and Quarter Repeater

This type of mechanism strikes the half hour, quarter hour and on demand. This would usually be performed using two notes and would let the wearer know the time to the nearest quarter or half hour.

Five Minute Repeater

The five minute repeater offers more accuracy to the wearer/owner by chiming the same as above, but also the nearest 5 minute intervals (again on two notes) so would theoretically chime up to eleven times per hour on demand.

Minute Repeater

This is the most complex repeater and Thomas Mudge is credited as the inventor of this mechanism. The wearer would hear the hour, the quarters, and then the specific minutes – giving the exact time to the current minute. This is often demonstrated ably by Tim Mosso on Watchbox videos. You can also see a demonstration here:

Grande Sonnerie

The primary difference with a sonnerie is that the striking is automatic, but can also be silenced by the wearer with a slider or used on demand. A Grande Sonnerie plays the hours and quarters at every hour or the minutes on demand.

Petite Sonnerie

Often called the “little sister” of the Grande Sonnerie, the Petite Sonnerie strikes the hours and quarters without repeating the hours at every quarter. If a watch was to feature both Sonnerie types, the owner can use a slider to switch between the modes.

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HOW REPEATERS WORK MECHANICALLY

There are three key points to consider for the construction of a repeating mechanism:

Gongs and Hammers

The gong is often a hand crafted piece of metal that curves around the outer edge of the case which is “hit” by the hammers, which are attached to springs that load up with energy and then are released to create the strike. The shape of the gong is finely tuned (often removed, mechanically reshaped and then replaced) so that the musical notes required are perfected. This often takes many iterations of work to create the perfect sound and is seen as one of the most complicated efforts in watchmaking.

A manufacturer has to fit several gongs and hammers into an arrangement and many different gongs and hammers will be required to strike a complex chime such as the Westminster Chime.

Construction and assembly of these elements is incredibly difficult. If any components are even slightly out of place, the function may not work correctly, or sound poor. Given the power of the springs for the hammer the vibrations or striking of the gongs may even deform components.

Mechanical “reading” of the time

How does the watch know which gongs and hammers to operate based on the time?

A complex mechanism has to be created that essentially reads the current time as an input, and then the output will be the correct striking of the gongs. A series of “snail cams” that sit on the primary train and as the standard time passes, rotates with it. The 4 tooth “quarter snail” cam keeps track of the 15 minute elements. A “ninja star” with 14 teeth also rotates and keeps track of the minutes past the 15 minute elements, and then finally an “hour snail cam” with 12 teeth keeps track of the hours of the day. Combining these always-running cams allows the watch to store the current time.

When the system is engaged for striking, the racks that are used against these cams are first primed in their starting position and as the springs that are charged with power the “beaks” that engage with the cams slide along, translating into power into the hammers themselves via springs.

Power delivery and engagement

When it comes to power, the large slider on the side of the watch to engage the repeating function not only engages the on demand function but also charges a separate mainspring for the repeating mechanism – there will be enough resistance in this lever to provide enough energy into the mainspring to deliver the maximum number of strikes required (at 11:59 – eleven hour strikes, three quarter strikes and fourteen minute strikes). A sonnerie function (as it is automatic) will either have to take power from the main power source (the watch mainspring) or from an individually wound mainspring dedicated to the mechanism, often accompanied by a power reserve indicator.

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MY FAVOURITE VACHERON STRIKING WATCHES

What I really love about minute repeater watches is when a manufacturer creates a timepiece that appears simple but covers up the massive complexity underneath. It’s no secret that I have a love for simple dials and the Patrimony Contemporaine Calibre 1731 (Reference 30110/000R) Minute Repeater fits the bill perfectly.

Released in 2013, it featured a 41mm case while being only 8mm thick (or thin!) in 18K pink gold. The most exceptional thing about it was that it was hailed as the world’s thinnest Minute Repeater while achieving amazing sound and a 65 hour power reserve. The price was around $365,000.

Reference 30110
Caliber 1731

The next striking watch that makes my top 3 is the Les Cabinotiers Minute Repeater Perpetual Calendar (reference 6610C/000G). This beautiful, special order timepiece with a blue dial & white gold case makes for a modern look (who doesn’t love a blue dial these days?) while building a perpetual calendar onto the caliber 1731 movement discussed previously. The watch grows in size to 42mm with a 10.44mm thickness over the reference 30110 but manages to preserve incredible legibility and classic calendar design ethos given the additional complexity. It’s just…wow.

Reference 6110C

My final favourite is the reference 4261 and it originates from the 1940’s. It was a 36mm timepiece and combined the oh-so-beautiful teardrop lugs, with a simple and classic dial layout. It was available in both gold and (much rarer) platinum. The movement was not certainly a Vacheron in-house movement but only 5.25mm and finished beautifully. At auction the platinum version achieved $605,000 !

Reference 4261

References:

https://en.wikipedia.org/wiki/Striking_clock

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