Danish 18 carat gold keywind chronometer watch Circa 1855

Open faced pocket watch by Jules Jürgensen
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A very rare gold Danish pocket watch with chronometer escapement and key winding, circa 1855.
Engine turned 18 carat gold case with monogram. Very early Jürgensen chronometer movement with extravagant structure, pivoted detent escapement, big ruby bearings, gold escape wheel, bimetallic compensation balance with blued arms, blued inside, blue hairspring and signature „Jules Jürgensen Copenhagen. Signed white enamel dial (fine hairline) with Roman hours, sunk subsidiary dial for the seconds and blued Breguet steel hands.
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Diameter: 49 mm
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Weight: 84 g
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Signed: Jules Jürgensen Copenhagen
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Literature reference of a nearly identical watch: John M.R. Knudsen “Urban Jürgensen & Sonner” Copenhagen 2003, pages 260-261.