English triple-cased verge for the Ottoman market Circa 1849-50

Silver, enamel and tortoiseshell verge watch by Edward Prior
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An English silver, enamel and tortoiseshell triple-cased verge pocket watch made for the Ottoman market, circa 1849-1850.
The watch features a full plate movement, verge escapement, chain and fusee, and a three-arm steel balance. The white enamel dial is adorned with Ottoman numerals and has steel fleur-de-lys hands. The protective case is silver and covered with tortoiseshell, decorated with studs. The two plain inner cases are both made of silver and bear hallmarks indicating their quality and the date of manufacture.
Signature on movement: Edwd. Prior / London / 66925 and on the dial: Edward Prior / London. All three cases have hallmarks, including the lion passant, the English quality mark for sterling, the uncrowned leopard’s head, and the date letter indicating 1849-50.
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Diameter: 76 mm
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Signed: Edward Prior London