Dutch one-handed pair cased verge pocket watch Circa 1680

Silver pocket watch with early balance spring by Jean Vrythoff Le Jeune
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A Dutch one-handed pair cased verge pocket watch with early balance spring, circa 1680.
Two cases: outer case silver, tortoiseshell covered, with stud decoration and large lateral hinge; inner case silver and polished. Silver, Champlevé dial with inlaid radial Roman hours, engraved and chased center with signature and blued steel single hand. Full plate movement, keywind, fire gilt and signed, with chain/fusee, tulip pillars, three-arm steel balance, and large florally engraved and pierced balance bridge.
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Diameter: 55 mm
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Weight: 125 g
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Signed: Jean Vrythoff Le Jeune, Maastricht
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Vrijthoff (Frijthoff) de jonge, working circa 1680, Maastricht.
The watch is a particularly beautiful example of a one-handed pocket watch with an early hairspring and a regulation mechanism according to Tompion.