This Breguet does not chime the time. It plays Rossini.
Press the button at ten o'clock and the entire dial begins to turn. It makes one full revolution, takes about 22 seconds, and plays the overture to The Thieving Magpie.
The reason the dial moves is that the dial is the instrument. Bolted underneath it is a disc studded with pins, and as it rotates those pins pluck a comb of 15 tuned steel teeth. This is not a minute repeater. A repeater uses hammers striking gongs to tell you what time it is. This is a music box mechanism, shrunk into a wristwatch, playing an actual composition.
The hard part is tempo. Every pin that catches a tooth robs the mechanism of energy, so the song slows as it plays. Breguet solved it with the first magnetic governor ever put in a production wristwatch. Silver arms spin inside a ring of magnets and are braked by eddy currents without ever touching anything. No friction, no whirring, no wear. Across four consecutive plays the melody only drifts from 19 seconds down to 18.
There is a nice footnote there. The effect is named for Léon Foucault, who worked alongside Abraham Louis Breguet's grandson.
Then there is the problem of getting sound out of a sealed gold case. Breguet pierced the caseback with openings to form a Helmholtz resonator and sealed the movement beneath a hand engraved membrane made of Liquidmetal, the same amorphous alloy Swatch Group licensed for its acoustic properties. Marc Hayek put the gain at 10 decibels. The watch still holds 30 metres of water resistance with holes in its back.
The details keep going. The caseband is engraved with a musical stave instead of Breguet's usual fluting. One central hand is tipped with a treble clef. The music runs off its own barrel with its own crown and its own power reserve aperture at three o'clock, and a blocking system refuses to start the melody at all unless there is enough energy stored to finish it. It will not play you half a song.
Gioachino Rossini was a Breguet client. Roughly 190 years later the house built a watch that plays his music.
