A demonstration of Montblanc’s mastery in the horological art, the Heritage Chronométrie ExoTourbillon Rattrapante Limited Edition 8 combines the Maison’s renowned tourbillon with a monopusher split-second chronograph.
The ExoTourbillon name explains one of the peculiarities of this timepiece. "Exo" means "outside" in the ancient Greek and, in fact, the rotating cage and the escapement of the tourbillon are positioned outside the movement’s plate and are located alongside the movement. Also, the large balance is installed outside the rotating cage and oscillates on a different plane.
Invented in 1827 by the Swiss watchmaker Louis-Frédéric Perrelet, then perfected by the Austrian Joseph Thaddäus Winnerl, the rattrapante chronograph includes two second-hands positioned one above the other: one of them runs continually whenever the chronograph function is active; the other can be momentarily halted at the push of a button to measure an intervening interval. When this button is pressed again, the temporarily halted hand catches up and returns to synchrony with its companion. The French verb rattraper means "to catch up", so Perrelet named his mechanism "rattrapante".
Thanks to the ExoTourbillon’s patented energy-saving construction, the tourbillon can be paired with a cleverly designed split-second chronograph function. Despite its mechanical complexity, this split-second function can work with the same barrel and the same power reserve as those of the basic chronograph movement — and can do so with greater precision than would be possible in a chronograph without the ExoTourbillon construction.
The Montblanc rattrapante complication works with two column wheels and a classic double clamp, which can be observed in motion through the transparent caseback. Once the chronograph complication is activated through the pusher integrated in the crown, both column wheels and the hand-bevelled levers, which are used to transfer the different commands, come into play. Thin steel springs that have been delicately curved then push the rattrapante clamps onto the split-second wheel, thus enabling the reading of the first measured interval when the wearer pushes the pusher located at the two o’clock position. Another push of the same pusher causes the clamps to spread apart so that the split-seconds hand catches up the chronograph’s elapsed seconds and keeps running with it. To stop and reset both chronograph and split-second hands, it is sufficient to push again the pusher integrated in the crown.
One of the major inspirations in the design of the Heritage Chronométrie Collection comes from the Minerva Pythagore timepiece. Housed in a slim polished gold case with curved horns and a stepped bezel, this wristwatch developed in 1948 featured a pure and elegant dial with applied Arabic numerals and indexes, as well as a precise minute scale.
The Minerva Phytagore from the Fifties
The three-dimensional dial of the Montblanc Heritage Chronométrie ExoTourbillon Rattrapante Limited Edition 8 is enhanced by raised counters and subdials that include different finishing — the small seconds subdial and the 30-minute counter both feature an azuré motif in the centre and an opaline decoration on the external ring, while the second time zone and day/night subdials have been embellished with a sunray pattern.
The ExoTourbillon is highlighted by a bridge with a looped shape that recalls the symbol of infinity. It takes one week to be hand-bevelled and polished by Montblanc’s artisans.
Completing the dial are faceted sword-shaped hands for the hours, minutes, seconds, second time zone and chronograph minutes, and baton-shaped hands for the day/night and chronograph seconds hands as well as applied red gold numerals and indexes.
The final touch is a refined grey satinated flange that is calibrated with a fifth-of-a second scale for the chronograph and that simultaneously shows the continually running minutes for precise reading.
Visible through the sapphire crystal caseback, the manufacture manually-wound calibre MB M16.62 is beautifully finished: the edges of the components are bevelled, the surfaces are brushed, and the flanks bear fine, elongated embellishments. Their bright polishing creates a nice contrast with the Côtes de Genève on the bridges, glossy red jewels, and gold-plated wheels.
Tested in-house for more than 500 hours to certify performance and quality, the Montblanc Heritage Chronométrie ExoTourbillon Rattrapante Limited Edition 8 (ref. 115993) comes in a 47 mm round case crafted in 18-karat red gold. Each of the exclusive 8 pieces has a price of Euro 270,000 / US$ 287,000. montblanc.com