Presented for the first time at the prestigious Salon International de la Haute Horlogerie 2015 (SIHH) exhibition in Geneva, the Montblanc Tourbillon Cylindrique Geosphères in red gold, an exclusive limited collection of just 18 pieces, was created to honour Vasco da Gama’s historic expedition began on 8 July 1497 with a small fleet of four ships.
Now, at Watches & Wonders haute horlogerie exhibition in Hong Kong, Montblanc unveils a white gold version Tourbillon Cylindrique Geosphères NightSky in a limited edition offering only 18 pieces worldwide.
The Tourbillon Cylindrique Geosphères NightSky Limited Edition is an eye-catcher with the 47 mm case and the large sophisticated dial, which unites a cylindrical tourbillon and a uniquely functional world-time indication.
Equipped with hand-wound calibre MB M68.40, this highly complex horology marvel displays following functions: a triple time zone with local time is displayed in the form of hours and minutes; the continually running and independently adjustable display for the home time is presented on a three-dimensional twelve-hour compass rose at “6 o’clock”; and a pair of globes depict the World´s 24 time zones in the Northern and Southern Hemisphere, along with the passage of the days and nights.
The 18 K gold dial is constructed in various parts and on different levels. Inspired by the two impressive globes, Montblanc’s designers have selected on round shapes and rounded décor. The upper section of the dial, which is night-black and adorned with aventurine, reflects the night sky and is the perfect backdrop for the tourbillon mechanism with its arcing, convex, polished tourbillon bridge.
The lower section of the dial, elaborately finished in dark grey, bears two globes and the home-time indication in the form of the three-dimensional compass rose. The hand that sweeps above this rose to indicate the hours is likewise styled in a “Fleur-de-Lys” shape.
The two miniature globes illustrate the passage of the days and nights in the northern and southern hemispheres. Engraving and miniature painting on these two halved balls indicate in relief the outlines of the continents, their borders and the oceans that separate them.
Their elaborately crafted and finely detailed design also shows the circles of latitude and longitude. The two globes are motionlessly affixed to the movement, while two 24-hour world-time indicator discs with the day/night display make one revolution per day around them.
The disc for the northern hemisphere turns clockwise; its counterpart for the southern hemisphere rotates anticlockwise. This arrangement enables the watch’s wearer to view, in the course of a single day, the sunlit halves of the two globes and the halves that are currently turned away from the sun. With the aid of the meridians of longitude, the viewer can read the current time in any desired part of the world by following the 24-hour world-time display on the two discs.
The continually running and independently adjustable display for the home time at 6 o’clock on the dial of the Tourbillon Cylindrique Geosphères NightSky Limited Edition inspired by the gigantic marble compass rose at the base of the Padrão dos Descobrimentos.
This monument, which commemorates Portuguese discoverers, stands in the civil parish of Belém in Lisbon. Comparable to a miniature sculpture, the watch’s compass rose is composed of four parts, each of which is entirely handmade and manually decorated.
Montblanc developed the 281-part hand-wound Calibre MB M68.40 featuring a 91-part tourbillon mechanism with a cylindrical hairspring which guarantees a power reserve of 48 hours. The balance-wheel frequency is 18,000 vibrations per hour, or 2.5 Hz. The moment of inertia, thanks to the 14.5 mm balance wheel, is 59 mg.cm².
Today, very few Manufactures still have the necessary expertise to produce balance-wheels and hairsprings. It was only possible for Montblanc to develop a cylindrical balance-spring for the Tourbillon Cylindrique Geosphères NightSky Limited Edition – 18 pieces because of the capacity to manufacture both components in the Montblanc Manufacture.
Unlike their flat counterparts, cylindrical balance springs were regarded as the summum bonum and installed only in the finest and costliest marine chronometers. Valuable ship’s chronometers were indispensable for seafarers because only with the aid of a clock that continued to show the correct time with great accuracy for a lengthy period of time were mariners able to determine their longitude on the high seas. Today too, a cylindrical balance spring continues to embody the utmost precision.
Like a conventional balance-spring, a cylindrical balance-spring is a concentrically wound elastic metal wire. However, instead of being wound side by side, at increasing distances from a common centre and all on the same plane, its individual turns are all of equal diameter and are wound one atop the other. This eliminates the slight eccentricity of the centre of gravity, which has always been the Achilles’ heel of the conventional balance-spring.
The challenges for Montblanc’s watchmakers were to miniaturise this type of balance-spring and to install it in the tourbillon mechanism of a wristwatch.
The extremely high degree of in-house fabrication skill at the Montblanc Manufacture in Villeret, combined with the expertise accumulated here over many years, enabled these specialists to create more than merely a “simple” cylindrical balance-spring: they further equipped it with two Phillips terminal curves.
The upward curvature at each end of the spring significantly improves the regularity of the balance-spring’s “breathing”, thus further reducing the isochronism error. Consequently, in this masterpiece, Montblanc achieved a highly accurate rate.
Incomparable beauty distinguishes the styling of the doubly curved three-dimensional endless loop of the Tourbillon Bridge, beneath which the tourbillon’s large cage completes one rotation around its own axis every sixty seconds. For the Tourbillon Cylindrique Geosphères NightSky Limited Edition, Montblanc’s typical tourbillon bridge departs for the first time from its usual planar shape and acquires a convex form. It thus perfectly harmonises with the two globes on the dial.
A master watchmaker requires more than seven days handcrafting this distinctive tourbillon bridge completely and giving it an absolutely immaculate polished finish.
The indicators on the Tourbillon Cylindrique Geosphères NightSky Limited Edition can be set via the crown, the visible pusher at 8 o’clock and the inset corrector on the case’s flank at 4 o’clock.
After pulling the crown outwards, the user can set the local time and simultaneously adjust the world-time display along the two globes’ 24-hour scales. The corresponding buttons on the case are used for the fine adjustment of the local time in the centre and the home time on the compass rose at 6 o’clock, which runs along with the local time.
Once all indicators have been correctly synchronised, a new local time in a different time zone can be set simply by pressing the push-piece at 8 o’clock. Operating this pusher advances only the hours-hand in single-hour increments. It does not affect the minutes, which are shown from the dial’s centre, nor does it alter the home time at 6 o’clock or the two displays along the globes.
When the watch’s owner is travelling, he or she can conveniently read the local time by referring to the hours- and minutes-hands in the centre, check the home time at 6 o’clock and see the time anywhere else in the world by referring to one of the two 24-hour discs around the globes.
The 16¾-line Montblanc calibre MB M68.40 is embedded in a 47-mm-diameter and 15.38-mm height white gold case. The alligator-skin strap is attached to the watch by four rounded horns that have been thoroughly and lavishly polished by hand.
The names of 24 cities in the Northern Hemisphere and another two dozen metropolises in the Southern Hemisphere are engraved along with the matching time zones on the back of the case. The limited numbers from 01/18 to 18/18 are engraved on the sapphire crystal in the back of the case.
Model: Montblanc Collection Villeret – Tourbillon Cylindrique Geosphères NightSky Limited Edition – 18 pieces
Montblanc Manufacture Calibre MB M68.40
Hand-wound mechanical movement with one-minute-tourbillon and a cylindrical hairspring, triple time zone with local time, home time and world-time indication
Dimensions: 16 lines ¾ (38.40 mm); height =10.50 mm
No. of components: 288, including 91 for the tourbillon cage
No. of rubies: 18
Power reserve: Approx. 48 hours
Balance: Screw balance, diameter = 14.5 mm, moment of inertia: 59 mgcm²
Frequency: 18’000 semi-oscillations per hour (2.5 Hz)
Hairspring: With Phillips terminal curves
Main plate: Rhodium-plated nickel silver with circular graining on both sides
Bridge: Rhodium-plated nickel silver with Côtes de Genève
Going-train: Gold-plated, faceted arms, diamond-polished surfaces
Local time: Central hours and minutes
Home time: World time with 24-hour-time-zones for the southern and northern hemisphere second zone time by hand at 6 o’clock
Tourbillon with a cylindrical hairspring and a unique double infinity hand-crafted bridge in three dimensions
18 K white gold
Crystal: Scratch-resistant, domed sapphire crystal with antireflective treatment on both surfaces
Back: Screw 18 K white gold with 24 cities of both hemispheres engraved and inset pane of sapphire crystal and
Dimensions: Diameter = 47 mm, height = 15.38 mm
Crown: 18 K white gold with Montblanc emblem in mother-of-pearl
Pusher: Local time pusher at “8 o’clock” and home time corrector at “4 o’clock”
Water-tightness: 3 bar
18 K gold, upper part with aventurine depicting the night sky of the southern hemisphere enhancing the Tourbillon Cylindrique and the double infinity slightly curved bridge
World-time indication on two discs with 24-hour time zones with day/night indication revolving around two fixed globes with traditional hand-painted “peinture miniature” for the oceans and engraving for the continents and the meridians showing the Northern hemisphere on the left and the southern hemisphere on the right
Home time indication at “6 o’clock” above a three-dimensional hand-crafted “rose des vents” subdial
18 K white gold hour- and minute-hands in the center, blued home time hand at “6 o’clock”
Hand-sewn black alligator-skin strap with folding clasp made of 18 K white gold