Extremely rare Swiss complicated repeating watch Circa 1906

Yellow gold open faced complicated pocket watch
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A very fine and extremely rare Swiss 18K yellow gold open faced gentleman’s minute repeating pocket watch featuring a perpetual calendar, moon phase, single pusher chronograph, and 30 minute counter. Made by Vacheron & Constantin in Genève, circa 1906. The watch features a mechanical movement with lever escapement, calibre RA 18”, bimetallic balance wheel, end curve balance spring, micrometric swan-neck adjustment, column wheel, 39 jewels, and crown winding and time setting. It has two hammers on a gong. The silvered dial includes black enamelled Breguet hour markers, a railway track minute scale, external 1/5th second graduation, and blued steel pear hands. Four auxiliary dials display: 48 months over 4 years and a 30 minute chronograph counter at 12 o’clock; date at 3 o’clock; moon phases, ages, and small seconds at 6 o’clock; and days of the week in French at 9 o’clock.
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The yellow gold case is basin shaped, hinged, and composed of four elements with a smooth reverse. The snap on, hinged bezel allows access to the movement. A slide at 9 o’clock activates the striking mechanism, while correctors at 3 and 6 o’clock enable quick calendar adjustments. The chronograph activation push button is integrated into the crown. The case is engraved: Vacheron & Constantin Genève Minute Repeater Chronograph Minute Counter Chronometer Moon Phases Perpetual Calendar. Comes with Vacheron Constantin Certificate of Authenticity.
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Diameter: 55 mm
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Weight: 165 g
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Signed: Vacheron & Constantin à Genève