The second mystery watch presented at SIHH 2013 by Cartier is the Rotonde de Cartier Double Mystery Tourbillon.
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 certiﬁed by the Geneva Seal.
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 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).
The watchmakers of Cartier have employed a disc of sapphire crystal with an anti-reﬂective ﬁnish to support the tourbillon 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 perform a revolution once every 5 minutes.
The manual winding 9454 MC Double Mystery Tourbillon movement is the result of long research. 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.
The platinum case has a diameter of 45 mm.