German keywind silver duplex pocket watch Circa 1850

Pair-cased duplex escapement
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A silver German Pair-cased pocket watch with duplex escapement, produced in Lower Saxony, circa 1850.
A silver outer- and inner case, white ename dial, Roman numerals, full plate movement, keywind, five-arm ring balance.
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Diameter: 55 mm
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Weight: 129 g
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Signed: Landwehr Vilsen
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According to Juergen Abeler, watchmaker Johann Albert Landwehr was born in 1819 and died in 1858. He used to live in Bruchhausen-Vilsen in Lower Saxony in Germany.