Sonnerie au Passage

The sonnerie au passage is a sound complication that chimes the hours automatically, without the wearer needing to press any button. It differs from the minute repeater precisely because of this: it is not on demand, but at passage. The watch decides when to chime — every full hour — and it does so on its own.

The mechanical principle is more subtle than it seems. Throughout the entire hour, the minute wheel accumulates energy in a spring or lever mechanism; when the sixtieth minute strikes, that energy is released suddenly onto a hammer, which strikes the gong or bell. In the MeisterSinger Bell Hora the process is clearly visible: the hammer loads progressively and the final strike is clean, not gradual. In the Chopard L.U.C. Strike One the hammer strikes the inner edge of the sapphire crystal, using the case itself as a resonance chamber — an ingenious solution but one that makes the sound very dependent on wrist positioning. Christopher Ward in the Bel Canto integrated the complication on an FS01 module mounted on a modified Sellita SW200 base: over sixty additional components for a solution that brought this type of striking into unconventional price ranges.

Historically, the sonnerie au passage was the practical answer to the absence of reliable artificial light: pocket watches from the eighteenth and nineteenth centuries used it to inform the user without looking at the dial. It is not a simplified form of the minute repeater — they are conceptually different complications. The minute repeater chimes on demand and marks hours, quarters, and minutes; the sonnerie au passage chimes spontaneously and generally only the hours, sometimes the quarters.

All calibers with this complication feature an on/off function, which may be found on a separate pusher, on the crown, or in an opening on the dial. It is a necessary precaution: an automatic chime in a meeting or at night is not always welcome. Deactivation does not stop the accumulation mechanism, but prevents the hammer from being released — a constructive detail that is far from trivial.

I am not aware of any documented cases of sonnerie au passage with quarter chiming on a regular production wristwatch: if they exist, they are prototypes or one-of-a-kind pieces. Those who speak to me about it usually confuse this complication with the grande sonnerie, which is something entirely different.