Vacheron Constantin Les Cabinotiers Solaria Ultra Grand Complication – La Première

Reading Time: 15 minutes

In 1755, Jean-Marc Vacheron signed his first apprenticeship contract, which defined the starting point of a quest for excellence and a human adventure. To embody 270 years of technical and aesthetic mastery, the Maison has developed the most complicated wristwatch in horological history, answering its motto of “Do better if possible, and that is always possible”. With 41 complications, this single-piece edition, which is the subject of 13 patent applications, is the result of eight years of research and development. Vacheron Constantin Les Cabinotiers Solaria Ultra Grand Complication – La Première is a masterpiece of innovation, that incorporates five astronomical functions never previously combined in watchmaking. With 1521 components, the new manufacture Calibre 3655 is housed in a white gold case with a 45mm diameter and a height of just 14.99mm, a true feat of miniaturisation. Complementing the technical achievement of this watch, its refined aesthetic is designed to optimise the legibility of its many functions. 

41 COMPLICATIONS, A TECHNICAL ACHIEVEMENT 

Grand Complication watches have been part of Vacheron Constantin‘s universe since its earliest days. Throughout the Maison’s 270-year history, this technical mastery has been powerfully expressed in the field of time measurement, musical, chronographic and astronomical indications, as well as in the art of combining them.

Since developing its first watch with a date calendar complication display at the end of the 18th century, Vacheron Constantin has continually pushed the boundaries of mechanical watchmaking, particularly in the field of astronomical complications – as illustrated by the pocket watch with 13 complications created in 1929 for King Fouad I of Egypt. More recently, Les Cabinotiers pieces such as the Celestia Astronomical Grand Complication 3600 (2017), Astronomical Striking Grand Complication – Ode to Music (2020) and Armillary Tourbillon Perpetual Calendar – Planetaria (2021), and The Berkley Grand Complication (2024) are distinguished not only by their aesthetics originality but also by rare combinations of astronomical complications.

The double-sided Les Cabinotiers Solaria Ultra Grand Complication – La Première watch is part of this long tradition of timepieces dedicated to the particularities of the solar system and the fascination that they exert. With its 1521 components, 41 complications and 13 patent applications, it is an inventive creation that transcends boundaries, in terms not only of complications and innovation, but also of miniaturisation. 

Three readings of time

To embrace the different concepts underlying the measurement of time, Calibre 3655 was designed so that it can display civil, solar and sidereal time simultaneously, with a gear train specific to each of them.  

Civil time – The first gear train is dedicated to the 24-hour day of civil time – the legal time used throughout the world, which is based on International Atomic Time. This is indicated on the front dial of the watch by the central hour and minute hands, complemented by the display of world time and a second time zone.

Sidereal time – The second gear train is dedicated to sidereal time, which is displayed on the reverse side of the watch; minutes are shown on the periphery of the fixed sapphire crystal caseback while hours are displayed on a rotating disc set beneath it. With a duration of 23 hours, 56 minutes and 4 seconds, one sidereal day is the time it takes for Earth to complete a full 360° rotation when taking a fixed star in the celestial vault as a reference point. Because Earth rotates on its axis while also revolving around the sun, it takes about four minutes less than a calendar day to return to its point of origin relative to the given star.

Solar time – The third gear train – known as the tropical gear – is devoted to displaying the peculiarities of solar (or tropical) time. Because Earth’s path around the Sun is elliptical, not circular, and since Earth’s axis is inclined at 23,4° to the ecliptic (the plane of its orbit), the time taken for the Sun to pass its zenith varies throughout the year. This difference between the solar day (true) and the civil day (average) of 24 hours, varies from -16 to +14 minutes depending on the time of year and coincides only four times in twelve months (the equinoxes and solstices). This differential, called the equation of time, is displayed on the counter at 6 o’clock on the front dial of the watch. 

INNOVATIONS AND TECHNICAL DEVELOPMENTS 

Work on the architecture of Calibre 3655, which unites all the astronomical functions on a dedicated mechanical module barely 2.8mm thick, prompted the Maison to do further research into the display of new astronomical functions. 

Five rare astronomical complications

Les Cabinotiers Solaria offers five innovative astronomical complications in an unprecedented combination, including a world premiere:  

• The position of the Sun 
• The height of the Sun 
• The culmination of the Sun 
• The declination of the Sun 
• Temporal tracking of celestial objects – world premiere

Four of these complications are related to the apparent path of the Sun and are displayed on the front of the watch – one on the periphery and three on the counter at 6 o’clock. The fifth one is displayed on the reverse side of the watch. 

Position of the Sun – Located on the periphery of the dial, this indication tracks the position of the sun in the sky when the watch is correctly oriented according to the cardinal points. Shown as a small yellow circle, it is screen-printed on a rotating sapphire disc that also displays sunrise and sunset times, and the length of the day.

Height of the Sun – The second complication displays the height of the sun above the horizon, a measurement expressed in degrees of angle that oscillate between 20° and 68° and indicated by a hand on the same counter as the equation of time at 6 o’clock. 

Culmination of the Sun – A third complication, displayed on the same counter, the culmination of the Sun refers to the time when the Sun reaches the highest point of its trajectory in the sky. Often confused with the zenith (point vertical to the observer’s horizon), culmination depends on the observer’s longitude. At this precise moment, we speak of solar noon, halfway between dawn and dusk.

Declination of the Sun – This ingenious indication corresponds to the angle formed between Earth’s equatorial plane and an imaginary line connecting the Sun to Earth. This declination of the Sun varies according to the seasons. In the Northern Hemisphere, it gradually increases from -23.5° at the winter solstice to +23.5° at the summer solstice, a value corresponding to the tilt of Earth. Measuring zero at the equinoxes, this solar declination is displayed by a hand vis-à-vis a three-dimensional gold representation of the Sun that is integrated into the counter at 6 o’clock.

Constellations and seasons – The counter at 6 o’clock, dedicated to the particularities of the Sun’s path, is also equipped with a rotating disc displaying the 13 astronomical constellations of the zodiac as well as the seasons, solstices and equinoxes. 

TEMPORAL TRACKING OF CELESTIAL OBJECTS, A WORLD PREMIERE 

In addition to the complications related to the course of the Sun, the fifth complication integrated into Les Cabinotiers Solaria watch is linked to the split-seconds chronograph. This new complication – a world first – combines a split-seconds chronograph with a representation of the celestial vault and makes it possible to calculate the time it takes for a constellation or a given star to appear in the middle of the observer’s field of vision. 

The technical development of the chronograph mechanism is the subject of a patent application about the pivoting of the split seconds and chronographs tubes that reduces the impact of stopping the split-seconds on the amplitude of the balance wheel while reducing any vibration. 

The chronograph readings are displayed on the back of the watch, with a 60-minute counter located at 12 o’clock and a peripheral graduation of seconds. The two split-seconds chronograph hands are anchored at the centre of the dial on which is represented the celestial vault.   

On a small rotating disc at the centre of the dial, mounted on the same axis as the chronograph hands, a green triangle indicates the time needed until a selected star will be seen in the viewer’s field of vision. At this moment, on the celestial vault, the selected star will position itself in front of the green index that serves as a reference point – marked on the ellipse shaded in dark grey on the sapphire crystal disc that displays the movements of the celestial vault.  

This sapphire case back is marked with a white circle representing the celestial equator (projection of the equator onto the celestial sphere) and a yellow circle for the ecliptic (plane of Earth’s orbit). The movement of the constellations is displayed in the observer’s field of vision in real time.

To operate the complication, the user visually selects a given star on the celestial chart, then activates the chronograph. When the chronograph hand reaches the green reference marker, stop the first hand but let the second hand continue until it reaches the current position of the chosen star, then stop the hand. The time (in hours) that must elapse until the user will see the chosen star in the sky is indicated by the green triangle on the small counter in the centre of the dial. The peripheral month display marked on the back crystal enables the wearer to adjust the celestial vault to reflect the Earth’s position in its orbit around the Sun. 

Perpetual calendar, Moon phases and tide measurement 

The astronomical functions are complemented by a Gregorian perpetual calendar. In a counter on the front dial at 12 o’clock, it displays all the indications – with day, month and leap years shown by a small indicator to the right of the counter. These are supplemented by digital dating according to the ISO 8601 standard, including the four-digit year shown within the counter, the week (1 to 52) on the periphery of the counter indicated by a green-tipped hand, and the day (1 to 7) in a small aperture to the left of the counter. 

Displayed on the counter at 9 o’clock, the astronomical Moon phase, including the age of the Moon, is driven by a dedicated gear train, with an accuracy maintained for 122 years, without correction. Because all the functions of this timepiece are pushed to their most accomplished interpretation, the lunar cycle is complemented by a mareoscope with details of spring tides and neap tides – two astronomical occurrences that each occur twice a month, reinforcing or diminishing the tidal amplitude (the elevation of tidal high water above mean sea level).

Hours and Minutes, GMT and world time indication

The time indications also reflect Vacheron Constantin’s quest for perfection. In addition to the central hands indicating hours and minutes, a counter at 3 o’clock displays a second 24-hour time zone with day/night indication. And, in line with the technicality of Calibre 3655, this mechanism is supplemented by a world time indication (according to standard wintertime – GMT zero) through a rotating disc bearing the names of the cities representing the 24 time zones. 

Adjustment in increments of one hour or one city is done by a single corrector set in the case side. To save space within the mechanism, the adjustment is achieved not via a clutch, as is usual, but by a differential. This technical development is one of the 13 patent applications filed for Calibre 3655. 

AN INNOVATIVE CHIMING MECHANISM 

Accounting for 7 of the 13 patent applications filed, the Westminster minute repeater mechanism is integrated into the base movement along with the chronograph mechanism and tourbillon regulator. One of the first challenges was to accommodate a chiming mechanism without compromising the thinness of the calibre – especially as the choice fell on a Westminster carillon, the most sophisticated of the musical sequences, involving four gongs and four hammers.

The second challenge was to ensure the sound quality of the repeater’s chimes. Because a multiplicity of movement components absorbs some of the sound vibrations, the more “cluttered” a box is, the less resonant the sound will be. 

The result of extensive research, the gongs are attached to the middle case and have been shaped with a rectangular section. This increases rigidity on the horizontal plane and thus amplifies the sound. As well as optimising resonance, this solution prevents the gongs from colliding when in operation while the watch is being worn.

However, this first solution had to be supplemented by a parallel development of the hammers. The aim was to maximise the transmission of kinetic energy at the time of strike, while minimising the rebound of the hammers. The solution was to design hammers with a new, particularly compact shape and increased mass. To increase the moment of inertia, the four hammers have been forged in steel with the addition of 18K gold on three of them. Also, to optimise the use of space, they are positioned in pairs on either side of the base plate.

Thanks to this new architecture and the developments made to the striking mechanism, which are the subject of seven patent applications, the musicality of this minute repeater is harmonious and richly sonorous. One of the patent applications is for a new selection method that allows the wearer to choose between an on-demand repeater of the hours only or the traditional hours, quarters and minutes. 

Miniaturisation, innovative design and sophistication of the dials

The imperative of miniaturisation has driven the entire conception, development and construction of the calibre, which is designed in two connected sections. The base movement combines the time, chronograph and chiming functions, while an additional mechanism combines all the astronomical indications.  

Given the number of complications integrated into Calibre 3655, the connection of the two was a challenge. To resolve this, Vacheron Constantin developed an ingenious “plug and play” mounting system featuring a fast and precise connection mechanism that guarantees perfect indexing. This system, comprised of two elements manufactured with precision, enables the astronomical displays to be driven by simply juxtaposing and attaching the additional module. Two sapphire components, perfectly fitted together, facilitate optimal energy transmission and allow for repeated connection and disconnection without wear, eliminating the need for additional parts. 

This solution makes it possible – during a watch service, for example – to disassemble the entire additional mechanism, including the dial and hands, in order to access the base movement. This ingenious “plug and play” fastening system is the subject of one of the 13 patent applications filed for the Solaria Ultra Grand Complication watch. 

The construction of the dial is as intricate as the movement. It comprises a main plate with four counters, under which two metal discs are inserted – one bearing the cities at 3 o’clock and the astronomical signs at 6 o’clock – as well as three sapphire discs, which require machining capabilities of the utmost precision. The peripheral disc displaying sunrise and sunset times and the one indicating the sun’s position measure only 0.18mm. A true feat of manufacturing and assembly. Finally, a third sapphire disc, also 0.18 mm thick, is positioned at 9 o’clock to precisely indicate Moon phases, including spring and neap tide occurrences. This disc is mounted above a metal disc that displays the tide cycle. 

Another patented innovation designed to reduce the movement’s overall dimensions is that the sunrise and sunset, equation of time, height of the Sun as well as culmination and declination of the Sun functions are managed by a two-sided monobloc multi-cam wheel system, which has reduced the height of the mechanism and increased its precision. 

On the reverse side of the watch, the fixed sapphire crystal and the rotating disc are also very thin. The fixed disc – which in fact is the transparent caseback and is marked with the months and constellations – is just 0.6 mm thick at its edge, and the rotating disc, which display the celestial vault and the sidereal time, is barely 0.3 mm thick. The two split-seconds chronograph hands, anchored at the centre of the dial, are made of aluminium to minimise weight. 

Such fine components are not only extremely demanding in terms of manufacturing but also pose a tremendous challenge during the assembly of the movement. 

PROWESS IN MINIATURISATION 

One of the major difficulties was to house the Calibre 3655 with its 1,521 components in a reasonably sized case that would be comfortable on the wrist. This was a real challenge that required not only extreme miniaturisation but also new solutions in terms of construction. The result is rare feat of watchmaking, with the Maison succeeding in housing a calibre with 41 complications in a case measuring 45mm in diameter with a height of only 14.99mm. 

A further challenge of miniaturisation was to display such a large number of functions in a very limited space, and to incorporate into the watch case the multiple pushers and levers required to activate them.  

The watchmaker who designed the movement was also responsible for the development of the watch’s case, along with a designer from the Maison. Generally, the exterior of a watch, including the case and dial, is the exclusive responsibility of the designer, whose task it is to ensure the legibility of the functions, the harmony of the shapes and the balance of the proportions. However, given the nature of this project, it was essential to entrust the technical development of the case to the person in charge of the movement. The result is an elegant case in polished 18K white gold, incorporating eight correctors, two push buttons, two selectors and an elegant slider for the minute repeater. 

AESTHETIC CHALLENGES 

The technicity of Les Cabinotiers Solaria watch required particular care not only in the finishing of the 1521 components – all of which is done by hand – but also in the display of the 41 complications. Given the concentration of complications, a major challenge was the legibility: four counters on the front, two of which display up to five complications each, and a back that combines a sky map and chronograph functions. 

Legibility of displays

On the front dial of the watch, an elegant play of contrasts enhances legibility. The striking absence of traditional ornamentation creates a distinctly modern aesthetic. White alternates with black, and different shades of grey are created by a variety of finishes – sunburst, sandblasted and circular satin-polished – with white gold indexes highlighted by rhodium plating and satin finishing.  

On the counter at 6 o’clock devoted to the solar functions, a 5mm diameter Earth dome in rhodium-plated 18K gold is highlighted by the contrast between highly polished continents with sandblasted oceans. The declination of the sun is highlighted by a polished 18K yellow gold half-sphere. 

On the reverse side of the watch, legibility is ensured despite the restrained colour palette. The sapphire crystal caseback displays the constellations, the equatorial ellipse (grey circle), the ecliptic ellipse (yellow circle), the months, and 60-second graduations. The rotating disc displaying the celestial vault and the 24-hour scale is achieved through metallization in two shades of grey. The two split-seconds chronograph hands, which traverse the star chart, are lacquered in green and red to maximise contrast, these colours are echoed in the 72-hour power reserve indication, which is set on the periphery of the movement to save space. The resulting display is reminiscent of a gauge on a car dashboard.  

The art of finishing

The finishing of the components required great attention to detail, especially since the miniaturisation work carried out on the entire Calibre 3655 was pushed to the extreme, which resulted in tiny and very fine components that required exceptionally careful handling. To showcase the fascinating architecture of the movement, the decoration of the components includes nine types of finishes: 

• Bevelling 
• Brouillage 
• Circling 
• Graining 
• Mirror polishing 
• Matt polishing
• Sandblasting
• Satin polishing
• Sunray brushing 

Among the details, the minute repeater hammers are mirror polished; the bridges are all angled and polished as well as chamfered with a matte, satin-brushed or “brouillage” finish; the jewel sinks are chamfered and the wheels circled; The main plate is circular grained, and the barrel ratchet is sun rayed. This alternation of finishes transforms the highly technical character of Calibre 3655 into a kinetic artwork.

INTERVIEW WITH CHRISTIAN SELMONI, STYLE & HERITAGE DIRECTOR

What are the key technical elements of this timepiece? 
Because it is the most complicated wristwatch in the history of horology, with an unprecedented 41 complications, the mechanism had to be arranged in the most logical and compact way possible. The main objective was to bring together all the main complications, timekeeping, astronomical, chronograph and chiming, on a single base plate. Thanks to this construction, it was possible to create a wristwatch with harmonious proportions. Many of the innovations of this watch are related to the solutions found to avoid adding bulk and to gain in energy efficiency. The 72-hour power reserve attests to the latter. 

So how do the dimensions of this watch respond to the standards of Haute Horlogerie?
The miniaturisation of the movement is an essential point – a real watchmaking feat. Accommodating 1521 components in a case for a chiming watch with a diameter of 45mm and a thickness of 14.99mm was indeed a challenge. Everything about the design of Calibre 3655 has been thought out with space constraints in mind, especially regarding the minute repeater with a four-gong and four hammers Westminster chime. Redesigned with more compact dimensions and greater mass, the hammers and gongs are positioned on either side of the base plate to gain height and efficiency.

Why is this piece referred to as an astronomical watch? 
This watch occupies a special place in horology, especially since it integrates astronomical functions related to the apparent course of the Sun across the sky. It is rare for a timepiece to display civil time with central hours and minutes, solar time with equation of time display, and sidereal time coupled with the movement of the constellations. Thanks to an innovative mechanism, it displays in real time the position of the sun, its height, the time of its culmination and its angle of declination. This construction requires differentiation in the gear trains to account for the peculiarities of the solar system – groundbreaking feats for a mechanical wristwatch.
The third astronomical complication – sidereal time – linked to the split-seconds chronograph function and displayed on the back of the watch, allows us to determine when a chosen star will appear in our field of vision.
These highly complicated mechanisms are part of a long tradition of astronomical watches at Vacheron Constantin, dating back to the early 19th century and including the Les Cabinotiers Celestia presented in 2017, which has 23 functions inspired by astronomy.  

You mentioned eight years of development for this watch. How many people were involved in the project?  
The creation of this new timepiece was different from the Reference 57260 and The Berkley Grand Complication pieces with a record number of complications – which each occupied three watchmakers for respectively eight and eleven years. A single watchmaker is behind the entire project of Les Cabinotiers Solaria. He designed the movement, imagined the case – which is a direct response to the movement architecture – and guided the choice of finishes to be applied to every element.

LIST OF COMPLICATIONS

Time measurement (6)

• Day and night indication for reference city
• Second time zone hours and minutes (on 24-hour display)
• World time indication for 24 cities
• Second time zone day and night indication
• 3Hz tourbillon with silicon balance wheel (with high Q factor)
• Civil time display module coupled to the base movement

Gregorian Perpetual Calendar (8)

• Perpetual calendar 
• Days of the week 
• Date 
• Months 
• Year indication 
• Leap-year indication 
• Indication for the number of the week within the year (ISO 8601 calendar) 
• Number of the day of the week (ISO 8601 calendar)  

Lunar indications (3)

• Astronomical Moon phases and age of the Moon 
• Tide level indicator 
• Spring and neap tides indication

Astronomical indications (14)

• Indication of seasons, equinoxes & solstices
• Position of the Sun
• Sunrise time (according to the city of reference)
• Sunset time (according to the city of reference)
• Duration of the day (according to the city of reference)
• Equation of time on tropical (solar) gear
• Culmination time of the Sun (according to the city of reference)
• Height of the Sun above the horizon (according to the city of reference)
• Declination of the Sun, Three-dimensional Earth showing the latitude of the Sun in the Northern/Southern hemisphere 
• Sidereal hours
• Sidereal minutes
• Astronomical zodiac signs
• Sky chart (according to the city of reference)
• Temporal tracking of celestial objects

Chiming complications (5) 

• Minute repeater
• Westminster carillon chime (4 hammers & 4 gongs)
• Choice of hour-only or full chime
• Crown locking system during the chiming
• Double-stop hammer system to limit rebound and optimise transmission of the hammers’ kinetic energy

Split-seconds Chronograph (4)

• Chronograph (1 column wheel)
• 60-minute counter
• Split-seconds chronograph (1 column wheel)
• Isolator system for the split-seconds chronograph

Additional feature (1)

• Power-reserve indication (outer disc at 190°)

LIST OF PATENT APPLICATIONS

Time indications – 2 patent applications 

• “Plug and play” system: ingenious system for fixing the astronomical module
• Universal time: ultra-compact system allowing local time to be dissociated from home time without a spring but thanks to a differential

Astronomical indications – 3 patent applications 

• Sunrise and sunset times, equation of time, height of the Sun as well as culmination and declination of the Sun: system by multi-cam monobloc wheel to reduce the height of the mechanism and increase its precision 
• Celestial vault: system for displaying the movement of the constellations in real time by means of two sapphire crystals 
• Identification of celestial objects: system to indicate the number of hours it takes for a selected star to enter the user’s optimal field of vision

Chronograph – 1 patent application 

• Split-seconds chronograph: split-seconds insulator system offering better isochronism and reduction of vibration

Minute repeater – 7 patent applications 

• Minute repeater architecture: developments to optimise the hammer size and maximise the energy transmitted to the hammers and then to the gongs for a better sound  
• Mode selector: system for selecting the striking mode on demand of the repeater, choosing between hours only or engaging the entire striking mechanism with hours, quarters and minutes