English gold chronograph with auxiliary seconds Circa 1847

An extremely rare English 18 carat gold open faced chronograph pocket watch with auxiliary seconds, circa 1847. Gilt full plate movement, chain/fusee, solid moulded movement pillars, English lever escapement, bimetallic screwed balance, blued balance spring, very finely engraved balance cock, screwed on regulator scale, set diamond endstone on balance. White enamel dial with Roman numerals, auxiliary seconds at 12 and gold spade hands. Plain case, casemaker’s punch mark FM. Movement and dial signed and numbered.
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Diameter: 51 mm
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Weight: 114 g