F.P. Journe Complications: The Centigraphe Souverain
One of Journe’s most sophisticated complications is also one of his most enigmatic.
The Centigraphe Souverain was not Journe’s first chronograph – that honor goes to the Octa Chronographe, which Journe introduced in 2001, and which was discontinued in 2007. The Octa Chronographe was in itself a remarkable achievement – the movement, automatic caliber 1300, was only 5.7mm thick, which was the same thickness as the version of the 1300 with just the big date complication; and there were other technical innovations as well. The Centigraphe, however, was a radical departure from business as usual. At launch in 2007, it was announced as a 1/100th of a second chronograph – that is to say, a chronograph capable of timing intervals as small as 1/100th of a second.
Normally, a very high frequency chronograph requires two separate gear trains – one for the main timekeeping train and one for the chronograph train; and each of those trains requires their own mainspring. If you want to have a chronograph capable of dividing up seconds into any particular increments, you generally have to have the separate chronograph escapement running at a suitable frequency.
The first very high frequency timer known is Louis Moinet’s “compteur de tierces” which was invented to time astronomical transits, and which could time intervals as small as 1/60th of a second. This was thanks to a very exotic form of cylinder escapement, beating at 216,000 vph (and before the compteur de tierces was discovered – or rediscovered – I would have confidently bet real money you could not run a cylinder escapement that fast, but Moinet did it, in 1816 no less.
Moinet’s compteur de tierces was not a chronograph in the modern sense in that it was not a combination of a conventional watch and a timer – it was instead, what today we would call a stopwatch. Modern very high frequency chronographs, like the TAG Heuer Mikrograph, which was introduced in 2011, follow the double train design principle – creating such a watch really pushes the limits of what is achievable with a mechanical oscillator, and requires the sort of metallurgy, tribology, and understanding of physics that you can really only get by expending enormous sums of money; it requires industrial level R&D.
Journe, in the years he was researching the Centigraphe, did not have access to industrial level R&D but what he did have was access to his own ingenuity. The Centigraphe took a different approach – a very different approach and one which excites argument to this day. To measure 1/100/second intervals you generally need an escapement which unlocks 100 times per second, which is to say, 6000 times per minute, or 360,000 times per hour – that is, an escapement with a rate of 360,000 vph. Journe, however, took a completely different approach, based on a complication most enthusiasts have never heard of: the foudroyante, also known as the diablotine, also known as the “lightning seconds.”
A foudroyante hand is one that makes one full rotation once per second. It’s quite rare – Lange & Söhne included one in their Grande Complication, and Jaeger-LeCoultre has a foudroyante as a signature complication in the Duometre à Chronographe. The foudroyante is usually a standalone complication – in other words, it’s not part of a chronograph; instead, it runs constantly, as long as the watch is running. A foudroyante hand jumps forward in discrete steps – in the Lange Grande Comp, for instance, five jumps per second. The hand is on the axis of a five pointed, star-shaped gear which is flicked forward every fifth of a second by a driving wheel on the axis of the escape wheel.
Instead of separate start/stop and reset to zero pushers, the Centigraphe has a rocker switch which performs the same functions.
The construction of the movement is highly unusual for a number of reasons.
First, the general layout is very different from a standard chronograph movement. The Omega caliber 321 is an excellent example of the typical approach.
Here, the mainspring barrel and going train are located underneath the chronograph works, which sit on top of the main going train and barrel, and which are visible from the back of the movement. The chronograph is driven by a driving wheel on the axis of the movement fourth wheel, and the driving wheel is connected to the chronograph seconds wheel, at the center of the movement, by the intermediate wheel at 12:00 in the image, which drops into position when the start button is pressed. This basic arrangement, with variations in the clutch system and position of the chronograph train wheels, is that found in the vast majority of chronographs.
In the Journe caliber 1506, the arrangement is completely different.
The first major difference visible is in the position of the chronograph works. These are located, not on the back of the movement, but under the dial. The reason for this is that the center of the movement is taken up by the mainspring barrel. The single large mainspring barrel provides 80 hours of power reserve with the chronograph switched off. With the chronograph switched on, autonomy drops to 24 hours – it’s normal for chronographs to show a reduction in power reserve when the chronograph is on, as the chronograph train adds friction and requires additional torque from the mainspring. However, an almost 75% drop is highly unusual and the reason is because the single mainspring drives the going train as it unwinds in one direction, and the chronograph train as it unwinds in the opposite direction.
The mainspring of a watch usually sits inside what’s called a going barrel – that is, the barrel rotates as the spring unwinds. The barrel has gear teeth on its edge, which drive the first gear in the going train proper (the center wheel). The innermost coil of the mainspring barrel is attached to an arbor (a thick metal cylinder) which has a gear attached to it called the ratchet wheel. This wheel is held immobile by a spring loaded “click” (the ratcheting of the click is responsible for the sound you hear when you wind a watch by hand).
This arrangement is very different in the Centigraphe. The barrel of the Centigraphe rotates and drives the first wheel of the going train in the normal way. However, when the chronograph is switched on, the innermost coil of the mainspring is free to unwind as well. This allows the upper barrel cover to begin rotating, and to power the chronograph train. The barrel continues to rotate, providing power to the going train, and the chronograph train gears power the foudroyante hand, which is flicked forward six times per second.
When the user stops the chronograph, the pinion for the foudroyante hand moves downward, out of engagement with the driving wheel on the axis of the escape wheel. The entire chronograph train layout is visible in the patent drawings
The mainspring barrel and cover are shown in outline at the center of the drawing; the foudroyante hand is mounted on the foudroyante wheel 4F, and the wheel 4F is driven by wheel 2 when the chronograph is engaged. The twenty second and ten minute hands (at 4C and 4B) are driven by the barrel cover as well.
You can now see why the power reserve drops so much when the chronograph is switched on – the mainspring is unwiding at both its outer and innermost coils. In practical terms, however, this will generally not present a problem as the chronograph registers are only designed for timing up to ten minute intervals.
Whether or not the Centigraphe is a true 1/100th second chronograph has been discussed many times since the watch was launched. The most direct answer is that it is not – the balance vibrates at 21,600 vph, not the 360,000 vph necessary for a true 1/100th second resolution. However, Journe’s solution is a close approximation. The foudroyante hand certainly rotates exactly once per second and can be stopped by the braking system at any point along its rotation, not just on a 1/6th second mark. The only caveat is that the movement of the hand is not continuous. It can clearly be seen stopping and restarting every sixth of a second as it rotates. Since the hand must accelerate to full speed from a stopped position six times per second, timing is not as exact as it would be if the hand rotated continuously, without stopping.
However, the effect appears to be minimal. Foudroyante systems are designed to operate with as little inertia as possible and the system in the Centigraphe, especially so; the action of the driving and driven wheels seems to have been made as light as possible. The Centigraphe may not narrowly fit the definition of a 1/100th second chronograph, but it is nonetheless an ingenious system, and an impressive piece of horological theater – and conversation piece.
Read part 2 of Journe Complications: The Tourbillon Souverain. And also Part 1, Journe Complications: The Chronomètre à Résonance. View our collection of pre-owned F.P. Journe timepieces, and see the F.P. Journe: Generations collection in person at our New York collector’s lounge.