Rotonde de Cartier Double Tourbillon Mystérieux

SIHH 2015

CARTIER

Rotonde de Cartier Double Mystery Tourbillon watch in pink gold

Imagine a watch equipped with a tourbillon that seems to be suspended in space. That was the challenge taken up by Cartier with its new movement, the 9454 MC Double Mystery Tourbillon  certified by the Geneva Seal. Slightly closer inspection will reveal the magic concealed in the mechanism. Indeed the flying tourbillon, which turns once on its own axis every 60 seconds, appears to be floating completely free in space, with no visible connection to any gear train. The illusion is complete when the same tourbillon cage starts to perform a second rotation at a rate of one turn every five minutes. This product of Cartier’s creative daring and watchmaking know-how, the Double Mystery Tourbillon, is the quintessence of over a century of mystery creations from the Maison.
 
Magic transformed into science 

In its simple elegance, which masks unbelievable complexity, the Rotonde de Cartier watch highlights a totally original mechanical construction named “Double Mystery”. The watchmakers of the Cartier Manufacture had to demonstrate boundless ingenuity in order for matter and movement to give birth to this fascinating kinetic sequence. When performing a conjuring trick, the magician has to distract the attention of his audience and convince them, by the illusion he produces, of the existence of preternatural forces. In the Rotonde Double Mystery Tourbillon, the design team took inspiration from the “tricks” of Jean-Eugène Robert-Houdin, the father of modern magic, to create the illusion of levitation.
 
Connoisseurs of watchmaking are aware that the mechanism of the tourbillon, in a vertical position, uses the rotation of the cage in a given time to shield the balance (the regulating organ) from the influence of the gravitational attraction of the Earth by smoothing out regularity errors (done by causing them to occupy every point on a circle in a given time). This fascinating device, set in the heart of the Rotonde Double Mystery Tourbillon, seems to defy the universal laws of gravity, giving the impression that it is floating unsupported in the void, and that its cage, rotating one turn in a minute and performing a complete rotation in its space in 5 minutes, has completely liberated itself from gravity.
 
Hiding what should not be seen

The watchmakers of the Cartier Manufacture have employed a disc of sapphire crystal with an anti-reflective finish containing an aperture the size of the tourbillon to give the best possible illusion of a cage in a state of levitation. To do this, they set the disc to support the cage in rotation. By doing this and positioning the minute wheel, which propels the oscillator, on the axis designed to limit the “resistance torque” inherent in the mechanism supporting the tourbillon, they succeeded in transmitting its force to the tourbillon, and thus causing the entire device to revolve in space once every 5 minutes. This results in the tourbillon making one full turn of the open, transparent space in 5 minutes, while the cage performs 5 complete revolutions in the same time... The ingenious way of achieving such a result is to place a rack
around the edge of this sapphire crystal disc, transforming it into a large gear wheel that performs one revolution every 5 minutes. 

Defying the laws of gravity 

The 9454 MC Double Mystery Tourbillon movement is the result of long research. For example, numerous calculations were needed to determine the speed of rotation of the different moving parts. To optimise power consumption, the cage of the tourbillon performs one complete rotation in the space dedicated to it over 5 minutes – making it perform one turn per minute would have consumed 25 times as much energy. To improve the mechanical efficiency of this moving organ, the weight of its components had to be reduced to the minimum in order to limit the inertia of the rotating assembly comprising the disc and the titanium tourbillon cage. To compensate for the weight of the regulating organ and the “flying” cage, although the weight of the latter had been reduced to the absolute minimum (0.28 g), a circle segment designed to relieve the toothing has been positioned opposite the tourbillon to restore the equilibrium between the masses, with the effect of creating dynamic balance.