The Rotonde De Cartier Minute Repeater Flying Tourbillon

Cartier has, over its 108-year history with the men’s wristwatch, occasionally produced some visually and aurally arousing timepieces. One such watch, a magnificent yellow-gold Tortue minute repeater from the 1920s, was proudly on display during the brand’s Time Art exhibition in Singapore, which traced its history in the craftsmanship of time-telling finery over the past century. In recent years, this watch was faithfully recreated with the addition of a small seconds indicator, using a Renaud & Papi repeater movement under the brand’s Collection Privée Cartier Paris line of timepieces. However, the new Rotonde de Cartier Minute Repeater Flying Tourbillon represents a quantum leap forward to Cartier’s new ability to craft a minute repeater movement fully in-house — a project that has occupied the last four years for one incredible watchmaker and her team.

Carole Forestier-Kasapi, the head of high watchmaking at Cartier, has been very busy in the last half-decade. She and her team have created 15 movements in four years — four of which received the hallowed Geneva Seal. They have, in that time, mastered (in no particular order) the flying tourbillon, the perpetual calendar, the GMT watch, and the column-wheel chronograph, and ushered in an entirely new vision of poetically inclined complications such as the Astroregulateur, a watch where the balance wheel is transplanted to the automatic rotor. Her team has gone from a handful of collaborators to 30 dedicated people in Cartier’s movement development team and 40 master watchmakers in its manufacture.

As you can tell from her watches, Forestier-Kasapi has two very defined aspects to her character. The first is whimsical, resulting in creations like the Astrotourbillon, an ingeniously irreverent reinterpretation of Abraham-Louis Breguet’s 200-year-old device, the tourbillon regulator. Here, instead of the cage containing all of the regulating components, rotating on its own axis, it takes a flight path around the perimeter of the dial, becoming the world’s most visually arresting seconds indicator. But she also has a decidedly serious side. And it’s this aspect that comes to the fore when she describes Cartier’s research into minute repeaters.

Before drawing even the first sketch for the new Rotonde de Cartier Minute Repeater Flying Tourbillon, she reduced this complication to its most basic element: sound. And before she was finished with her research, she’d learned enough about sound to teach a PhD class on its properties.

She explains, “Before we started work on the minute repeater, we dedicated ourselves to studying sound. What is sound? It is an acoustic wave produced by vibration. Sound is characterized by four things: intensity, tone, tonality and deadening.”

As Carole describes these things, her enthusiasm grows, and she scrutinizes your eyes to ensure that there is a flicker of comprehension beyond them. She continues patiently, “Intensity is sound, as measured in decibels. Human beings begin to hear sounds in excess of 10 decibels. Thirty decibels is considered to be the threshold for human beings to still be able to sleep. When we hit 90 decibels, sound becomes too strong for the human ear. What is interesting about sound is that its growth is not linear. For example, going from 10 decibels to 20 decibels, you have the sensation that sound has not doubled, but tripled in intensity. Between 10 to 15 decibels, you might feel as if sound has actually doubled.” But the truth is that the horological universe is literally littered with loud minute repeaters that don’t necessarily sound beautiful. As independent watchmaking’s spiritual father and creator of the first grande and petite sonnerie wristwatches, Philippe Dufour says, “It’s one thing to create a loud minute repeater; it’s another thing to create one with a beautiful song.”

When the subject of her repeater’s song comes up, Forestier-Kasapi gets excited. You see, she has already formulated her response, which consists of breaking the vocal quality of the sound into its various components. She explains, “Tone is a factor of two kinds of waves: fundamental, which are major undulations, and harmonics, which are minor undulations. Together, they give personality to sound. If you want, they create the signature of a sound. Tonality defines the perception between high and low notes. We hear frequencies from 20 to 5,000 Hertz, and each note has its own frequency. Deadening is the sound’s resistance, or its duration — the speed at which sound dies.” Together, all of these contribute to the qualitative experience of sound. Forestier-Kasapi continues gleefully, “So after realizing all this, how did we translate what we learned into a watch? Aha! That is the question.” And while your mind is still reeling from the previous analysis on all things sonic, she explains, “The important things when talking about a watch relate to acoustic transparency, vibration transmission, resonance, surface area and vibration velocity.”

How loud a repeater is has to do with acoustic transparency, which is the ratio between the mass of the watch and the mass of the gongs. This should favor the gongs as much as possible.

Forestier-Kasapi explains, “It is for this reason that we offer the watch in a titanium version — because this has excellent acoustic transparency. But many people are misinformed about titanium. It is not a better material for striking watches because of its innate qualities, but simply because it is much less dense and much lighter than gold or steel.” For those who prefer their watches in more traditionally noble materials, you can also have the new Rotonde de Cartier Minute Repeater Flying Tourbillon in rose gold, at a sacrifice of five decibels (it’s 63dB, versus 68dB for the titanium watch). If you are vacillating between the two, Forestier-Kasapi suggests the titanium watch. “Five decibels is a lot,” she explains.

Regardless of which you choose, both are among the loudest commercially produced minute repeaters around. In comparison, the Jaeger-LeCoultre Master Minute Repeater, the world’s loudest when it launched in 2005, is
55 decibels (measured from a distance of 50cm) — a level achieved by attaching its gongs directly to the sapphire crystal.

The argument for diminishing the mass of the watch in favor of the mass of the gongs brings to mind Hublot’s 2011 repeater with a carbon-fiber case. During his PR spiel, Hublot’s Jean-Claude Biver describes realizing that carbon steel made the best gongs, and this led him to deduce that carbon fiber would have the ultimate sound-transmission properties. Says Forestier-Kasapi with typical forthrightness, “Carbon fiber does make for excellent acoustic transparency. It has nothing to do with its innate properties, but simply because it is light and has very little density. If your case is heavy, you will have a small sound; if your case is light, you will have a big sound. It is as simple as this.”

To have excellent vibration transmission, you must create as much rigidity between the object that is vibrating (the gongs) and the object that is transmitting the resulting sound (the watch case). As such, in the Rotonde de Cartier Minute Repeater Flying Tourbillon, Forestier-Kasapi used four points of transmission between the movement and the case, and two more points at which the gongs were fixed to both the movement as well as the case.

Resonance surface area is optimized using the large 45mm-sized Rotonde case. Says Forestier-Kasapi, “A case of this size actually enhances the sound transmission. Of course, the important thing here is that when you enlarge the case, you make every effort to keep it light, so as to optimize the case-mass versus gong-mass ratio.”

It seems logical that if you want to optimize vibration transmission, you need as strong a vibration as possible. This means creating high vibration velocity. Forestier-Kasapi and her team studied many possibilities for gongs and
hammers before deciding on gongs with square cross-sections, which provide a larger contact point for the hammers. Says Forestier-Kasapi, “Optimizing the contact area between the hammer and gongs is incredibly important; it helps each strike to be more consistent, as well as powerful.”

She explains, “We use very heavy square-shaped steel gongs. The steel we use is very hard and very dense. It has the hardness of 680 Vickers, which is just about as hard as you can make steel. But one other factor is the hammer strike. It would be incorrect to say it is the speed of the hammer strike that is important, because it is the torque generated by the hammer strike that is critical. As such, the weight of the hammer is very important; you want a lot of weight to maximize the impact.”

Then came the task of tuning the repeater to provide the best possible tonality. Says Forestier-Kasapi, “The choice of notes is fundamental to achieving good harmonic quality and purity of sound. We worked with some experts in this field, and eventually arrived at two notes: ‘B’ in the fifth octave for the low note, and ‘D’ in the sixth octave for the high note.” To aid in the audio clarity of these notes, Forestier-Kasapi selected a flying regulator for the watch which, through the design magic of Cartier, has been transformed into a stunning kinetic flourish on the dial.

When I bring up the dual aspects of her personality, Forestier-Kasapi rebuts that she is, in turn, channeling the dual aspects of Cartier. The brand is at once whimsical and filled with a buoyancy of emotion, yet belied by a slavish devotion to quality and function.

She explains, “We started this project four years ago to really make a classic watch. This is not an example of creative complication, as you see in the Astroregulateur or the Astrotourbillon. We did not want to reinvent the minute repeater, but make one that was superb in sound and construction and was uniquely Cartier. Even though we were classically inclined with this watch, it is still totally in the spirit of Cartier. Look at the dial and you will see that because we have reversed the movement, you see the tourbillon at 12 o’clock, counterpointed by the flying regulator at six o’clock that spins with this wonderful animation each time you activate the repeater function. You also see the hammers and gongs on each side of the regulator, in what I feel is a superbly balanced configuration. One of our focuses at Cartier is to align wonderful in-house movements, designed and constructed
with total integrity, with our house’s beautiful aesthetic sensibility. At Cartier, design and construction must coexist. By turning the movement back to front, you have the [opportunity] to see, through the sapphire caseback, the strike train of the watch, consisting of the cams, the fingers and the toothed racks interacting with each other each time the repeater is activated. To me, the minute repeater is one of the most complex watches. And I feel it would be a shame to hide this incredible mechanism underneath the dial, as well as the beauty of our Geneva Seal finish. The watch is a representation of what Cartier brings to the watch industry. We are always about emotion, but we are also about high technical achievement. We are totally dedicated to the creation of true haut de gamme, complicated watches — but always using the emotional magic of Cartier.”

With that, I realize that Forestier-Kasapi has summed up the Rotonde de Cartier Minute Repeater Flying Tourbillon’s uniquely Cartier-like ability to marry emotion, design ingenuity and high-complication brilliance into one watch, leaving me at a loss for words, enjoying the stirring peal of its gong in the silence that remains.