English historical silver Observatory Chronometer Circa 1856

Open faced pocket watch by royal watchmaker Dent
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An English historical interesting Observatory Chronometer with accompanying documents, circa 1856.
Original silver case with gold hinges, London hallmarks 1856 and matching numbers on case and movement; Earnshaw pocket watch chronometer with cylindrical hairspring, diamond endstone, main plate signed and numbered, “Watchmaker to the Queen”; signed and numbered enamel dial with Roman hours, sunk subsidiary dial for the constant seconds and blued steel hands.
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Diameter: 57 mm
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Weight: 159 g
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Signed: P. Dent London
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This very fine pocket watch chronometer had a service at the Royal Observatory in Greenwich, papers are available. There is also a change of letters from 1871 about the “Chronometer of the Admiralty, Dent 23609”. According to Greenwich archive documents, this chronometer was the deck watch used in the “Ashantee Expedition” on the H.M.S Argus 1871 and was returned to the Observatory in 1873.