Unusual Swiss silver centre seconds chronograph Circa 1885

Silver open faced center seconds lever chronograph
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An unusual Swiss silver open faced chronograph lever pocket watch, Hallmarked Birmingham 1885. Gilt three quarter plate keyless movement with going barrel, plain cock with polished steel regulator, compensation balance with blue steel spiral hairspring, club foot lever escapement. White enamel dial with Roman numerals, a subsidiary at twelve for time, flyback centre seconds chronograph with large minute recording subsidiary running counter clockwise, and blue steel hands. Engine turned case with a silver cuvette, gilt winding button. Maker’s mark CF in a rectangle.
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Diameter: 51 mm
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Signed: No name
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An unusual dial design for a chronograph. The plate marked ‘Patented Aug 29th 82’.