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A foudroyante is a fast-moving watch hand—usually on a small subdial—that displays fractions of a second. Also called a “flying seconds hand,” it often appears with a chronograph, but the name alone does not mean it can start, stop and reset to time an event.
What a foudroyante indicates
The term describes a fraction-of-a-second display. The hand typically makes one full turn each second, while marks around its subdial divide that rotation into smaller intervals. The number of divisions varies by movement: documented examples show fourths, fifths, sixths or eighths of a second. Monochrome’s glossary uses “flying seconds hand” for the display, while its chronograph explainer describes the different possible divisions.
In practical terms, the hand’s position indicates a fraction within the current second. It is not simply a more finely marked conventional seconds hand: its rapid rotation makes those subdivisions visible as the second passes.
Does a foudroyante measure elapsed time?
Not necessarily. A foudroyante is often incorporated into a chronograph, where it can show fractions during a timed interval. But some designs run continuously and are not connected to the chronograph. Check the particular watch’s mechanism rather than assuming that a foudroyante hand can be stopped and reset.
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Chronograph-linked display
When linked to the chronograph, the foudroyante can indicate fractions of a second as part of the elapsed-time measurement.
Continuously running display
Greubel Forsey’s Nano Foudroyante EWT is an example of a different arrangement: Monochrome’s 2024 article describes its one-sixth-second indication as continuously running and not coupled to the chronograph. In that configuration, the hand displays fractions as time passes rather than counting a stopped interval. Monochrome’s report describes the model-era details.
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Why the divisions vary
The dial divisions relate to the movement’s operating frequency, so not every foudroyante indicates the same fraction. In a Habring² example reported by Monochrome in 2010, a rate of 28,800 vibrations per hour is associated with eight displayed fractions per second. The article’s example illustrates one configuration, not a universal specification. Read the 2010 report.
For a particular watch, read the subdial markings and the manufacturer’s movement description together. The markings tell you how the dial presents the fractions; the movement specification helps explain the divisions used.
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What the complication demands of a movement
A hand making a full rotation each second requires additional energy. Monochrome’s chronograph explainer notes that some watchmakers use a separate barrel for the chronograph and foudroyante functions to address that demand. The precise power arrangement depends on the watch. Monochrome’s chronograph explainer discusses the complication and its energy needs.
Examples in watches
Habring² Felix Foudroyante
Monochrome’s 23 December 2020 article describes a 38.5 mm salmon-dial Felix Foudroyante with the hand-wound AM11F calibre. It combines a foudroyante display with central jumping seconds. The article reported a price of EUR 6,550 at publication; that is historical reporting, not a current price or availability confirmation. See the 2020 model report.
Greubel Forsey Nano Foudroyante EWT
Monochrome’s 2024 article describes a one-sixth-second display that runs continuously rather than being coupled to the chronograph, and reports a limited edition of 11 pieces. Those are article-era specifications and edition details, not confirmation of current inventory. See the 2024 report.
Quick Recap
How to assess a foudroyante watch
- Connection: Is the hand linked to the chronograph, or does it run continuously?
- Resolution: What fraction does each division represent, and how many divisions appear per second?
- Power: Does the watch describe a separate barrel or another arrangement for the added mechanism?
- Currency: Are the cited specifications, price and availability current, or do they come from an older model report?
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
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