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Here is the latest hint on one of the complications it shall feature: The Armillary Sphere Tourbillon
The newly created and mesmerising Armillary sphere tourbillon is a visual and technical wonder that has been entirely constructed in-house at Vacheron Constantin.
This tourbillon has been named “Armillary” because of its visual similarity to the interlocking circles and rings of the scientific instrument known as the “armillary sphere”. The company’s watchmakers have been inspired too by the masterpiece of the legendary 18th century French maker Antide Janvier – a four-sided clock supporting a mechanical astronomic armillary sphere that was ordered by King Louis XVI in 1789.
With such inspiration, they have created the most supremely elegant mechanism displayed as a three-dimensional constantly rotating sphere gliding with the utmost delicacy simultaneously in three directions. The frame of the cage itself, made of ultra-light aluminium and housing the escapement is ingeniously constructed to incorporate the Vacheron Constantin company logo of the Maltese cross. Once every 15-seconds during the tourbillon’s rotation, the Maltese cross becomes fully visible to the viewer.To further enhance this exceptional mechanism the watchmaker has also chosen to use a spherical balance spring which not only adds to the elegance of the mechanism, but its special properties contribute to the accuracy of the watch.
Experimentation with the tourbillon mechanism in attempts to improve its function was pioneered by the exceptional German watchmaker Alfred Helwig (1886-1974) technical director of the Deutsche Uhrmacherschule, who invented in 1920 what is now commonly known as the flying tourbillon – a free-standing cage supported from only one side without any kind of bridge, this made it possible to make the movement as flat as possible. However it was Helwig’s pupil Walter Prendel, one of only four students to ever graduate the Deutches Uhrmacherschule in Glashutte with honors, who first constructed a tourbillon with the cage slightly tilted out of the vertical in 1928. This meant it was never in a completely vertical or horizontal position which eliminated the two most extreme variations. Prendel’s invention led to significant improvements in rate.
The concept of a tourbillon rotating on more than one axis was in fact first expressed in 1921 by Sir David Salomons, the legendary collector and authority on A.L. Breguet, who wrote “Breguet invented the tourbillon, which gets rid of certain position errors, but if the balance again turned a complete revolution out of its plane at the same time the tourbillon was working, then all position errors disappear…”. Not being a watchmaker, Salomons could never put his idea into practice himself but it was this idea that more than 50 years later must have inspired the British watchmaker Anthony Randall to construct his first dual-axis tourbillon in 1978 for which he obtained the patent in 1982. Based on Randall’s work, another British watchmaker, Richard Good made the first triple-axis tourbillon, a mechanism that captivated all who saw it. Both Anthony Randall’s and Richard Good’s dual and triple-axis tourbillons were fitted into carriage clocks and therefore did not have to endure sudden changes in position as did classic watches. They are however the foundation for all today’s multiple-axis tourbillons and without a doubt, the most remarkable horological creations both technically and visually. The expiry of the patents for those first multiple-axis tourbillions has allowed modern-day watchmakers to further develop the triple-axis tourbillon, work which has culminated in this extraordinarily sophisticated armillary three-axis tourbillon now incorporated in this Vacheron Constantin masterwork.
Two further exceptional and historic watchmaking inventions have been included in the making of the escapement; a spherical hairspring and the use of diamonds for the jewels of the pallets in the escapement.
The spherical hairspring (balance spring) used in the context of the armillary tourbillon has great visual appeal in echoing and enhancing the overall spherical design of the tourbillon, it also has a practical purpose. Devised in 1814, by the famous Swiss watchmaker Jacques-Frederic Houriet who demonstrated that a hairspring of spherical form gave the most perfect isochronism. In watchmaking, the aim of the watchmaker is to make a watch “Isochronous” meaning that the timekeeping of the watch is unaffected by fluctuations in the amplitude or swing of the oscillating balance caused when the watch is going from a fully wound state to a state of unwind. When the mainspring is fully wound the balance swings at its widest, as the mainspring’s power subsides, the amplitude naturally decreases. Isochronism adjustment involves making the hairspring in such a way so that its frequency is independent of its amplitude. As Houriet demonstrated, the spherical-form hairspring is the most effective spring to make a watch isochronous, however, they are very difficult to create and subsequently are only ever found in the most sophisticated watches.
The pallet fork of the escapement in this watch is made with the exceptional feature of diamond pallets which are at the same time both very hardwearing and low friction. Such pallets are extremely challenging to make and very few watches have ever been made with diamond pallets. They have a historical context both in the wider history of watchmaking and in the history of Vacheron Constantin itself.
