Cartier Rotonde de Cartier Astromystérieux

Cartier Rotonde de Cartier Astromystérieux: transparently magical

Inspired by the Mystery Clock Model A from 1912, the Rotonde de Cartier Astromystérieux revisits transparency with the sole aim of allowing us to experience the fascination the magic of invisibility holds.

By Vincent Daveau
Contributor

Mysterious watches and clocks are instruments clearly designed by artists who are as gifted with watchmaking tweezers as they are with a magician’s wand. The perfect blend of transparency and mechanics have caused experts familiar with watchmaking kinetics to challenge their knowledge as no traditional watchmaking design can explain how energy is transmitted to the new-generation movement revolving in space at the center of the watch's case. The design enthralls enthusiasts in the same way as the now-famous magic trick where a magician saws through a box containing a fantasy creature. Of course, it is all an illusion in both cases but their impact is striking.

Rotonde de Cartier Astromystérieux Calibre 9462 Rotonde de Cartier Astromystérieux

Whirling levitation

But let's concentrate on pure watchmaking science. Jean-Eugène Robert-Houdin (1805-1871) invented the clock with seemingly levitating hands. A watchmaker and an illusionist, he is considered the father of modern prestidigitation. Yet, his invention could easily have been forgotten had Louis Cartier not taken a keen interest in this creative way of displaying time. Thoroughly revisited today by the team of watchmakers from La Chaux-de-Fonds led by Carole Forestier Kasapi, the art of mysterious time display has now been reintroduced in a new collection that could be called "mysterious gravitational kinetics".

The question of how far watchmakers can go in challenging their own skills is often asked but the answer to that remains a mystery. Indeed, it is almost impossible to understand how the rotation of a mechanical whole manages to display time with the hands that the skeletonized movement is supposed to control.

Rotonde de Cartier Astromystérieux Calibre 9462 Rotonde de Cartier Astromystérieux Calibre 9462

Mobile movements

Even a novice will immediately notice that the Rotonde de Cartier Astromystérieux - available in only 100 copies in a 43.5-mm case made in bright palladium of millesimal 950 - has no component linking the winding crown to the movement (ref. 9462MC). And thus, the obvious question is how the manual winding caliber is actually wound and how the time is set. To maintain the illusion of void, technicians used transparent sapphire discs.

Invisible winding

The first disc supports the structure of the frame that combines all the movement components, namely the barrel, the gear and the regulating group (the escapement wheel, the lever and the balance). The second disc is used for winding and a “floating” pinion triggered by the winding stem activates it. The latter is equipped with a gear disconnecting system (no doubt dynamometric) to limit the risk of overloading when the watch is wound.

Activating the crown makes the pinion move, thus creating a physical link with the disc (picture it as a sort of big transparent ratchet) that enables the spring to be wound invisibly.

Calibre 9462 The Calibre 9462 with the mysterious complication

Secret time setting

The lower disc found on the base of the movement is used for setting the time and plays, hence, a double role. On the one hand, it brings enough flexibility for the movement frame to rotate at a normal pace. On the other hand, when the crown is pulled, it activates the time setting system (filed for patent). A lever – also filed for patent – blocks the sapphire disc that operates at a normal pace. The caliber rotates around a center point (the hour wheel). The disc linked to this wheel is simply disconnected to make the caliber (with the minute hand) rotate without any risks and simultaneously make the hour hand that is directly linked to the caliber interact. Once the appropriate time is displayed, the crown only has to be pushed back to block the disc again and thus allow the movement to resume its work.

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