French open faced chronometer pocket watch Circa 1870

Silver open faced pocket watch by École Nationale d’Horlogerie de Besançon
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A French graduate’s piece lever chronometer of the watchmaking school Besançon, circa 1870.
The case is silver, the dial is white enamel with Roman numerals and subsidiary seconds.
It has a bridge movement, cal. LeCoultre and a large screw compensation balance. Movement and dial signed.
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Diameter: 53 mm
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Weight: 99 g
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Signed: École Nationale d’Horlogerie de Besançon