English silver precision open faced pocket watch Circa 1851

Silver open faced chronometer watch by Barraud
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An English precision pocket watch with chronometer balance in the manner of Pennington, circa 1851. Sold to company William Bond & Son, Boston, and in 1852 and 1853 mentioned in their records. The case is sterling silver with gold hinges, hallmarks London 1851, and case maker’s punch mark GH (George John Hammon). The signed dial is white enamel with radial Roman hours, auxiliary seconds and gold hands. And it has a full plate movement with a chain/fusee, a spring detent escapement according to Thomas Earnshaw, a heavy Pennington-type gold/platinum screw balance, and a free-sprung blued helical balance spring with both sides passing terminal curves.
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Diameter: 57 mm
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Weight: 160 g
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Signed: Barraud, 41 Cornhill, London