Duomètre à Chronographe
The chronograph reinvented by Jaeger-LeCoultre
The Watch Quote™ - September 5th, 2007
This year, the Manufacture maintains this intensive pace of innovations with the unveiling of a new collection, the Duomètre, and the presentation of the first model in the line, the Duomètre à Chronographe. The latter’s distinctive styling and unprecedented technical features clearly place it in the most exclusive echelons of watchmaking fine art. This genuine micromechanical revolution houses a new-generation Calibre 380, nicknamed “Dual-Wing”. Two independent mechanisms respectively serve to drive the time display and an additional function, while a single shared regulating organ ensures chronometer-worthy operating precision without having to renounce the use of a complication. As the first representative of the new lineage, Calibre 380 is the first chronograph mechanism with no coupling-clutch, offering peerless time-measurement precision and read-off to the nearest one-sixth of a second. Housing this movement and endowed with a new case featuring welded lugs and a finely grained dial, the Duomètre offers a superlative reinterpretation of a great watchmaking classic.
The Dual-Wing concept
The new Duomètre line immediately commands attention with its brilliant new movement construction concept. Two separate watch mechanisms – one for the time display and another for an additional complication – are synchronised by a single regulating organ. Each of these mechanisms has its own source of energy and there is no interaction between the two. The only element they share is the regulating organ that supplies them with the time basis.
The first movement to embody this new construction concept is Jaeger-LeCoultre Calibre 380. It drives time displays with chronometer-like accuracy, as well as a chronograph that is unprecedented in terms of its indications and its precision.
One going train is entirely dedicated to the conventional time-display function (hours, minutes, seconds), and the other to the chronograph function, including a one-sixth of a second jumping-seconds hand. Each mechanism is powered by its own barrel, ensuring a 50-hour power reserve (50 hours for the time and 50 hours for the chronograph). There is no transfer of energy in either direction. A single crown serves to wind the two barrels: when rotated clockwise, it winds the time; and when turned counter-clockwise, it winds the chronograph. This calibre is housed within the very first chronograph wristwatch to operate without any need for a coupling-clutch to handle the start/stop functions of timing operations. A single push-piece ensures perfect coordination of the five chronograph counters.
Close-up mouvement 19RMCCS-1898
The chronograph reinvented by Jaeger-LeCoultre
The art of measuring and counting off periods of time has always been a source of fascination to humankind. Theoretically speaking, a chronograph mechanism and the layout of a chronograph dial must be extremely accurate and suited to repetitive and continuous use without ever jeopardizing the exactness and precision of the measurement.
Nonetheless, by its very nature, a classic chronograph mechanism is directly activated by the seconds wheel and draws the energy required to drive it from the same mainspring as that of the time-display mechanism. As its name implies, a coupling-clutch mechanism couples the chronograph mechanism to the time-display mechanism when starting an operation, and then uncouples it when the timing operation is stopped. The disc-based vertical coupling-clutch is the most effective type used today, and it minimises the losses in energy linked to this mechanism. Nonetheless, it cannot avoid significant variations in the precision of the watch when running with or without the chronograph in operation. Differences that may be negligible for measuring short times become far less so over longer periods of time.
Applying the original Dual-Wing movement concept to the chronograph does away with the need for a coupling-clutch. The precision of the watch is not influenced by the chronograph. The Duomètre à Chronographe may therefore be considered as the first authentic chronometer-precision complication watch.
The construction principle of the Calibre 380 uses a fascinating horological device to replace the coupling-clutch: the jumping-seconds mechanism. Mounted on the arbor of the escape-wheel, an additional 30-toothed wheel transmits the cadence of the balance to a six-toothed wheel. The latter performs a complete rotation every second, and shows one-sixths of a second via a hand at 6 o’clock. By a reduction process, a kinematic chain enables it to display the chronograph seconds, minutes and hours. A finger-piece activated by the column wheel serves to stop the jumping-second star in an intermediate position that thus enables the jumping- second escape-wheel teeth to move past without touching it. When the chronograph is restarted, the finger-piece is withdrawn, the torque supplied by the chronograph barrel sets the star rotating again, and the latter once again engages with the 30-toothed wheel. Creating such a simple and yet subtle mechanism within such a diminutive space calls for exceptionally precise components as well as the kind of watchmaking talents that only a Manufacture mastering the full range of watchmaking professions is able to provide.
The jumping-seconds mechanism was used for the first time in 19th century pocket-watches. At the time, the jumping-seconds hand was directly activated by the fourth wheel of the watch in order to indicate fractions of a second. For this reason, the jumping-seconds hand kept on running continuously and could not be stopped or reset. Jaeger-LeCoultre watchmakers would not have dreamt of presenting a chronograph worthy of its name without a resettable jumping- seconds hand. For the Calibre 380, they therefore developed a system making it possible to reset the jumping-seconds hand at the same time as all the other chronograph counters.
Remarkably beautiful and superbly finished, Jaeger-LeCoultre Calibre 380 features a large balance wheel (11.5 mg.cm2) beating at a frequency of 21,600 vibrations per hour, meaning six vibrations per second. Jaeger-LeCoultre has chosen the appropriate one-sixth of a second fraction not only for the jumping-seconds counter, but also by precisely dividing any seconds indication into six parts so as to ensure that the central time and chronograph hands can move exactly over a scale with one-sixth of a second markings.
Both aesthetically and functionally, the Duomètre à Chronographe is an exceptionally designed watch distinguished by absolute clarity and readability – a real challenge in light of the complexity of the functions. Two large subdials are arranged symmetrically, one at 10 o’clock with the watch hour and minute hands, and another at 2 o’clock with the chronograph hour and minute hands. An aperture in the chronograph subdial reveals a disc indicating the minute-units from 0 to 9 and thereby facilitating accurate reading of the times being measured. This new display, for which a patent has been filed, enables one to visualise at a glance the time elapsed in hours and minutes, for example 2 hours and 6 minutes, without needing to carefully
study the position of the minute hand. The dial also carries two power-reserve indicators, one at 7 o’clock for the conventional watch hands and the other at 5 o’clock for the chronograph. The jumping-seconds hand which jumps in one-sixth of a second increments is cleverly positioned at 6 o’clock, below and between the watch and chronograph subdials.
In order to handle this vast array of indications, the team of designers headed by Janek Deleskiewicz have allocated a colour code to the various functions. The hands linked to the standard time function and indicating the minutes, seconds and power-reserve are gold-plated or rhodium-plated, depending on the version; whereas those for the chronograph hours and minutes, the numerals on the minute-disc, the chronograph seconds and the jumping-seconds hands are in blued steel. This distinctive colour coding ensures instant reading of the time and of chronograph measurements at any given moment, even when the indications are in operation.
The complex nature of the watch is easily mastered when starting, stopping or resetting the chronograph mechanism. Each time the single pushpiece located at 2 o’clock is activated, it operates in the exact same start-stop-reset, start-stop-reset sequence. Each press in fact starts, stops and resets all five key functions: chronograph hour and minute hands, the minute-unit disc, as well as the central chronograph seconds hand and the jumping-seconds hand. Admiring the intricate resetting ballet performed by the four chronograph hands and the disc is a truly fascinating experience.
Exceptional aesthetics and decoration
Such a prestigious watch naturally features a superb exterior as well as movement finishing worthy of the most exceptional Haute Horlogerie creations. The new case of the Duomètre is distinguished by polished welded lugs and an elegantly satin-brushed caseband. The dials are finely grained and carry the movement or watch number on a dedicated plaque at 6 o’clock. All the slender hands and pointers are exquisitely elegant.
Embodying an entirely innovative concept, the Jaeger-LeCoultre 380 ‘Dual-Wing’ movement powering the limited edition of the Duomètre à Chronographe may be admired through the sapphire watch crystal. The independent barrels are snailed and bevelled by hand, while the ratchet-wheels are sunray-brushed with engraved and gilded “chronograph” and “hour/minute” indications. The bridges, habd-bevelled with polished sinks, reflect the Dual-Wing concept through taut, straight shapes for the standard watch mechanism, contrasting with arabesque motifs for the chronograph revealing the hearts, hammers, jumper-springs, column wheel and all the intricate workings of this mechanism. This decoration is inspired by the brand’s traditional pocket-watches. The going trains are circular satin-brushed with hand-polished sinks. The wheels and pinions, also hand-bevelled or embellished with polished sinks, feature snailed or smoothed-off surfaces. And finally, the flame-blued steel screws underscore the complex nature of this exceptional calibre.
As the first model in this prestigious lineage, the Duomètre à Chronographe watch will be issued in pink gold and platinum, while an 18-carat yellow gold edition will be presented in a limited series of 300.
The Duomètre vividly illustrates Jaeger-LeCoultre’s unassailable position in the highest spheres of technical watchmaking. Although the watch might look deceptively simple to the uninitiated, the first Duomètre à Chronographe may well prove to embody the ultimate in chronographs – at least until the appearance of a new creation destined to take its place in this exceptional lineage.