Rare Swiss gold triple bridge tourbillon chronometer Circa 1880

Gold open faced chronometer with tourbillon by Girard-Perregaux
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A fine and rare 18 carat gold open faced triple bridge tourbillon pocket chronometer, circa 1880. Nickel finished triple bridge movement, Guinand type 2 polished steel tourbillon carriage, pivoted detent escapement, bimetallic compensation balance, blued steel hairspring. White enamel dial with Roman numerals and subsidiary seconds. Case, pendant and bow finely chased with foliate scrolls, glazed display back. Dial and movement signed.
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Diameter: 55 mm
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Signed: Girard-Perregaux Chaux-de-Fonds Marqués de Santa Maria