Unusual Swiss gold repeating center seconds lever Circa 1912

Gold open faced minute repeater with center seconds by Patek Philippe
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A rare, unusual Swiss 18 carat gold open faced minute repeating center seconds keyless lever watch, circa 1912. Ultra thin nickel finished lever movement, 27 jewels, bimetallic compensation balance, wolf’s tooth winding, minute repeating on two hammers on to two gongs, repeat activated through a slide in the band. Gold cuvette. White enamel dial with Breguet numerals, outer calibrated minute track, red Arabic five minute divisions and center seconds. Plain case. Case, dial and movement signed, case and movement numbered.
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Diameter: 47.5 mm
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Signed: Patek, Philippe & Cie Geneva, Switzerland