Chiming watches hold a special place within the world of horological complications. For more than two centuries, these complex mechanical devices have been given pride of place by Vacheron Constantin. The new Les Cabinotiers Split-Seconds Chronograph Tempo ref. 9740C/000R-B692 is the crowning embodiment of this approach, with its 24 complications orchestrated by the new in-house 1,163-part calibre 2756. This is yet another one of the most complicated wristwatches ever produced by the Maison along with the Vacheron Constantin ref. 57260 —the most complicated watch in the world ever created with its 57 complications— and the Les Cabinotiers Celestia Astronomical Grand Complication ref. 3600 with 23 complications, amongst others. The Vacheron Constantin Les Cabinotiers Grand Complication Split-Seconds Chronograph Tempo took five years to develop.

This one-of-a-kind —unique piece— double-sided model displays the time, split-seconds chronograph measurements and perpetual calendar information on the front, while the back is devoted to astronomical functions, including solar time, equation of time, sunrise and sunset times, duration of day and night, as well as age and phases of the moon. Additionally, adding to the 24 complications in this watch, the Les Cabinotiers Split-Seconds Chronograph Tempo also features a tourbillon regulator and a minute repeater. Thanks to its ingenious strap attachment system, the watch can be worn on either side of its dials. As far as the minute repeater goes, Abbey Road Studios, a partner of the Maison, has recorded an original sound print delivered as a one-off certificate for this timepiece.

In terms of looks, the watch features two slate grey dials with sunray and guilloché finishes around the circumference to ensure perfect legibility. Cased in a very generous 18K 5N pink gold case measuring 50 mm in diameter by 21 mm in thickness, the brown alligator leather strap with large square scales sets the finishing touch to the aesthetic appeal of this watch.

The Front Dial

In addition to the minute repeater function, which must take into account the positioning of the gongs and their harmonious sound when struck, the front side also displays timekeeping and calendar indications in addition to the split-seconds chronograph. The perpetual calendar indications are provided by the two lower subdials: one for the day and date, the other for the month, and leap year. The symmetrically placed upper subdials are dedicated to timekeeping. The hours appear on the left- hand subdial at 10 o’clock with an inner 24-hour disc that can be used to display a second time zone; while the right- hand subdial at 2 o’clock shows the minutes on the outer disc and carries the chronograph 30-minute counter on the inner disc.

Given that the chronograph is doubtless one of the most complex horological complications to be integrated into a calibre, the watchmakers at Vacheron Constantin wanted to express the true measure of its nobility by creating a split-seconds chronograph equipped with a column wheel. The split-seconds system with two central hands enables intermediate —split— times to be calculated by stopping one of the two hands which, once restarted, catches up with the first.

But in order to reveal the full scope of this horological feat, the watch must be turned over. With its perfectly symmetrical case and thanks to the ingenious removable strap attachment system, Les Cabinotiers split- Seconds Chronograph Tempo is perfectly reversible and can be worn on either side, according to the mood of the moment.

The Back Dial

On the back dial, the central hands, including the minutes hand with a sun symbol, indicate true solar time. Based on the apparent displacement of the Sun, the latter differs from civil time due to the inclination of the Earth’s axis and the eccentricity of the Earth’s orbit. Mean solar time —the civil time that punctuates our daily lives— and true solar time coincides only four times a year, with maximal variations ranging from 16 minutes and 23 seconds to +14 minutes and 22 seconds. The difference is what is known as the equation of time, which, on this timepiece, is of the ‘running’ kind, given the simultaneous nature of the two readings of time on either side of the watch. This information is complemented by indications of sunrise and sunset times as well as the duration of day and night, respectively positioned at 3 and 9 o’clock.

The lowest part of the dial features a display of the age and phase of the moon by means of a retrograde hand sweeping over a semi-circular subdial. Here too, watchmakers have not taken the easy path with this high-precision moon-phase display, which requires only one correction every 1,000 years. To ensure the visual harmony of this second dial, the tourbillon is majestically enthroned at 12 o’clock with its carriage shaped like a Maltese cross —the emblem of Vacheron Constantin— topped by a pointer-type power- reserve indicator on the central pinion.

This timepieces with its multiple functions and displays represents an authentic watchmaking challenge. Firstly, on a technical level, with this calibre developed by the same team as that behind Reference 57260 and in which the smallest detail has been taken into consideration. Witness the split-seconds lifting- lever, designed to save energy for a timepiece that thus enjoys a remarkable power reserve of 65 hours and still lasting up to 40 hours even with the chronograph activated.

Sticker Price Upon Request. For more info on Vacheron Constantin click here.