F.P. Journe

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An interesting article on Centrigraphe....

An interesting article on Centrigraphe which I have just found.... Here are some of the excerpts (taken from Revolution Issue 11, by Ian Skellern)

Power for the chronograph function-

"Journe has used a similiar mainspring configuration to the one he invented for his Sonnerie Souveraine. The mainspring unwinds from both its inner and outer ends; the going train (timekeeping) is powered traditionally from the mainspring barrel; while the chronograph function takes its power from the (central) barrel arbor. This effectively isolates the operation of the chronograph from the timekeeping function, so that  there is virtually no drop in balance amplitude when the chronograph is activated."

Measuring intervals smaller than 1/16th of a second-

"When the chronograph is activated, the high-speed flying seconds hand does not spin smoothly like a figure skater, but jumps in micro-increments of 1/16th of a second, as expected for a balance oscillating at 21,600 vph.
The logical question then is: how can it possibly measure intervals of time smaller than 1/16th of a second?
Journe has achieved this by driving the flying seconds from both the going train of the movement working off the barrel and the chronograph train driven by the barrel arbor. When the chronograph is clicked to stop the measurement of elasped time, a pinion is vertically disengaged, disconnecting the escapement from the flying seconds, and simulaneously braking the hand.
This enables the flying seconds hand to stop any position along its dial - even between two 1/100th of a second divisions.

The mechanism is technically brilliant; however as I mentioned earlier, the 1/100th of a second precision may be more theoretical than real, as inconsistencies induced by the user's reaction time and the functioning of the micro-mechanics will certainly introduce practical limitations."