Les Cabinotiers Dual Moon Grand Complication: New in-house movement with 11 complications

Source:  Images and content by Vacheron Constantin

• One-of-a-kind double-sided watch housing new manual-winding in-house Calibre 2755 TMRCCQP and 11 horological complications including a minute repeater, a perpetual calendar, a precision moon phases, a sky chart.
• Extremely complex timepiece with an atypical face accentuated by the double central display of the moon phases.
• Highly elaborate design ensuring perfect readability of the time-related and astronomical indications.

With its time-related and astronomical complications regulated by a tourbillon and completed by a minute repeater, the manual-winding 2755 TMRCCQP calibre powering this watch is a masterpiece of complexity with its 774 components. Representing one of watchmaking’s most sophisticated grand complications, this white gold single-piece edition displays its indications in a perfectly legible manner. Stemming from an aesthetic quest dedicating elegance and purity of style to the service of technical sophistication, this timepiece is notably distinguished by the Maison’s characteristic retrograde function as well as by the refined finishes highlighting the double moon phase display that is the key feature of this watch.

The initial intention behind the Les Cabinotiers Dual moon Grand Complication watch was to pay an original tribute to the Moon. Often relegated to the background, the moon display is now very much in the forefront on this model, asserting its striking presence both by its colour code and by its size. As the idea was also to offer a vision of the Earth’s satellite as it appears in the northern and southern hemispheres, the central moon phase indication, already a rarity in the watchmaking world, is therefore characterized by a double display. This complication, already featured in the Les Cabinotiers Tourbillon armillary perpetual calendar –Planetaria watch, makes a strong statement in this highly technical musical timepiece with an astronomical vocation and 11 complications.
 

Front: a spectacular show

Indications:
– Off-centre mean solar time with hours and minutes
– Precision moon phases and age in both hemispheres
– Gregorian perpetual calendar with day, month, leap-year indications and instantaneous retrograde date hand
– Minute repeater
– Precision moon phases and age for the Northern and Southern hemispheres

The full measure of Vacheron Constantin’s ingenuity in staging the art of watchmaking is stylishly and elegantly expressed in this double-sided watch. This highly complex model is distinguished by the legibility of its hourly and astronomical functions, stemming from the Maison’s characteristic aesthetic quest perpetually focused on essentials.

On the front of the watch, the eye is drawn to the depiction of the moons in the two hemispheres on a disc coaxial with the central hands and shaped like a starry dome. Its deep blue colour makes a striking contrast with the silvery hue of the dial as it performs a complete rotation in 59 days, 12 hours and 45 minutes. Such is the tempo given to so-called astronomical moons, which scrupulously respect the duration of the synodic months with a discrepancy of only 24 hours every 122 years and 16 days. The age of the Moon is indicated around a periphery scale graduated from 1 to 29½. On this titanium dome graced with rhodium-plated moons on a blue-sky background obtained by physical vapour deposition (PVD), the meticulous care devoted to details – orchestrated in nine stages and involving nearly 56 hours of work – adds an additional original touch. The uneven surface of the moon, like the brilliance of the tiny stars, was achieved by diamond cutting: a micron-level high-precision machining process which gives faceted depth to the material that shines or sparkles differently depending on the angle from which the light plays across it.

The display of the hours and minutes of mean civil time complete with lunar cycles has been slightly off-centred upwards to enable the harmonious integration of calendar indications. Instead of the traditional pointer-type dials used for perpetual calendar indications, Vacheron Constantin’s Master Watchmakers and designers opted for rotating discs. This solution adopted for a mechanism that follows the vagaries of the Gregorian calendar without any need for correction before 2100, is admittedly more complex on a technical level yet offers greater flexibility in the arrangement of the indications to ensure more convenient readings. The semi-instantaneous display of the day and the instantaneous display of the month and leap-year appear through apertures, as does the date display. Here again, this display positioned on the upper rim of the dial is shown through a semi-circular window, but with a retrograde hand. A technical and stylistic signature of Vacheron Constantin since the early 20^th century, retrograde mechanisms require great precision in the doubling of the gears used to store the energy required for the return of the indicator.

The four-part dial construction and the finishing of each fully matches the technical nature of the model. A 0.35 mm thick sapphire dome is placed on a silver-toned metal baseplate with a sandblasted finish and openworked calendar apertures. This dome beneath which the moon-phase disc turns is fitted with two ‘masks’ whose smoky appearance is achieved by metallisation. It is held in place by a curved brass ring, satin-brushed with an opaline varnish, which in turn bears the white gold hour-markers.

Back: a cosmic dimension

Indications:
– Tourbillon regulator
– Sky chart
– Sideral hour display

The likewise multi-part rear dial construction ensures the clarity and understatement of the various displays. To ensure the moon phases take priority on the front of the watch, the opening revealing the tourbillon regulator has been placed on the back. Invented at the beginning of the 19^th century, this device enclosing the escapement and the balance-and-spring assembly in a mobile carriage is designed to compensate for the effects of Earth’s gravity on the isochronism of the regulator and thus ensure enhanced precision. The one-minute-rotating tourbillon is distinguished by its carriage shaped like Vacheron Constantin’s Maltese cross emblem, with its delicately hand-polished bar. To diminish the weight (hence improving performance) as well as for aesthetic reasons, the tourbillon components have been skeletonised – notably the fixed wheel which is entirely openworked.

The architecture of the dial on the reverse side also reflects a desire to create an astronomical watch with a display of sidereal time and constellations against a celestial backdrop. This timepiece paying homage to the Moon naturally had to integrate the notion of sidereal time – also known as “sidereal hour angle” – enabling astronomers to calculate the meridian of the stars. Using a fixed star in the sky as a reference point, the time it takes the Earth to complete a full 360° revolution – or sidereal day – is exactly 23 hours, 56 minutes and 4 seconds. As the Earth both spins on its axis and revolves around the sun, it takes about four minutes to return to its starting point in relation to the given star.

A fixed dial, bearing a blue dot representing the celestial horizon, is positioned below a movable sapphire crystal engraved with the constellations, while the rim features month markings as well as five-day graduations. By performing a complete rotation according to sidereal time, this mobile disc gives the exact position of the constellations – delimited by the celestial horizon – at the time when the watch is consulted by pointing it Northwards. Sideral time is read off counter-clockwise, facing the current date on the fixed PVD-treated blue outer ring bearing a 24-hour scale along with the cardinal points.

Minute repeater

This timepiece featuring 11 of the noblest horological complications laid out in an extremely elegant manner would have been inconceivable without making it a musical watch incorporating a minute repeater. To create this particularly complex striking mechanism controlled by a repeater slide housed on the caseband, Vacheron Constantin’s Master Watchmakers drew inspiration from La Tour de l’Île. This double-sided anniversary watch produced in a 7-piece edition for the Maison’s 250^th anniversary is the most complicated wristwatch ever made with its 16 complications, including a minute repeater with a centripetal strike regulator. This silent system also found in the Dual moon Grand Complication enables the duration of the musical sequences to be perfectly timed in order to obtain a distinct and harmonious sound of the notes played for the hours, quarters and minutes by the hammers striking two circular gongs. As an additional feature, the gongs of this repeater have been slightly ovalised to avoid them overlapping the tourbillon and without affecting their crystal-clear sound.

Calibre 2755 TMRCCQP, a watchmaking adventure

In-house Calibre 2755, one of Vacheron Constantin’s major developments, was chosen to power all these functions, which are complemented by a minute repeater chiming the hours, quarters and minutes on demand. This movement has undergone major transformations over the years – notably in the realm of astronomical functions – and represents a true horological adventure. The Les Cabinotiers Dual Moon Grand Complication watch with its 774 components is perfectly in tune with this adventure that has already seen Calibre 2755 interpreted in many ways through designs testifying to the quest for elegance amid complexity. Endowed with a 58-hour power reserve, Calibre 2755 TMRCCQP beats at a rate of 18,000 vibrations per hour.

Circular satin-brushed and hand-bevelled, with a Côtes de Genève motif on the rear bridges as well as mirror-polished hammers and strike-regulator bar, this in-house movement has been meticulously finished. To ensure a smoother match with the 46 mm-diameter case in 18K white gold, it has also been entirely rhodium-plated. As is the case with all timepieces from the Maison, this model showcases the extreme attention to detail lavished on every component, even those that remain invisible once the movement has been assembled. This quest for excellence is expressed as much in the technical and aesthetic choices and decisions as in the painstaking finishing.

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Summary

A single-piece edition created by Vacheron Constantin’s Les Cabinotiers department, this double-sided Dual Moon Grand Complication watch with its 11 time-related and astronomical complications regulated by a tourbillon and enhanced by a minute repeater radiates a rare degree of elegance. The latter is expressed through the perfect legibility of the functions as well as the meticulous care devoted to the details of the decoration and finishing. The result is an understated and complex watch endowed with self-evident functions. The front thus features the precision double moon-phase display, with its age, an impressive show staged in the dial centre and complemented by the hours, minutes and perpetual calendar indicators. The latter is notably distinguished by its retrograde date, a Vacheron Constantin technical and aesthetic signature. Astronomical indications appear on the reverse side of the watch with the time of the sidereal day – which is four minutes shorter than the civil day – and with a sky chart showing the position of the constellations in real time. The back of the watch also features an opening revealing the tourbillon and its Maltese cross-shaped carriage. Incorporating a minute repeater chiming the hours, quarters and minutes on demand, the model is powered by Calibre 2755 TMRCC QP, whose base movement represents one of the brand’s major developments.

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TECHNICAL DATA

Reference                                 
9770C/000G-007C

Calibre                                      
2755 TMRCC QP
Developed and manufactured by Vacheron Constantin
Mechanical, manual-winding
33.30 mm diameter, 11.20 mm thick
Approximately 58 hours of power reserve
2.5Hz (18,000 vibrations/hour)
774 components
50 jewels
Hallmark of Geneva certified timepiece

Indications                                    
Front side:                                 
Hours and minutes
1-      Minute repeater
2-6   Perpetual calendar with retrograde date with instantaneous hand return, semi-instantaneous day and month & year instantaneous
7-8 Precision Moon phases and age of the Moon for North and South hemispheres

Back side                                  
9- Sideral hour indication (24H)      
10- Celestial chart 
11- Tourbillon

Case                                          
18K white gold
46 mm diameter, 17.10 mm thick

Dials (face & back)                 
Metal, Sand blasted silvered
18K gold hands and applied hour-markers

Strap                                         
Dark blue Mississippiensis alligator leather, hand-stitched, saddle-finish, large square scales

Buckle                                       
18K white gold folding clasp
Half Maltese cross-shaped

Box                                            
Les Cabinotiers box

Unique timepiece
« Les Cabinotiers », « Pièce unique », « AC » hallmark engraved on caseback