Swiss watch with free sprung chronometer escapement Circa 1850

Silver open faced pocket watch
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A rare, large Swiss, silver deck chronometer with footed spring detent escapement and helical balance spring, circa 1850. An engine-turned case and a hinged matte gilt cuvette engraved with the technical details. White enamel dial with radial Roman numerals, outer minute track, large subsidiary seconds and blued steel Breguet hands. A matte gilt, three-quarter plate movement, the barrel with separate bridge secured by two screws, fusee and chain, maintaining power, jewelled Earnshaw-type escapement with footed two-spring detent, cut bimetallic compensation balance with temperature and meantime adjustment screws, free-sprung blued steel helical balance spring. Dial signed.
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Diameter: 70 mm
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Signed: No Name
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This is an unusually large Swiss mid-19th-century deck watch with chronometer escapement. The escapement is basically of Earnshaw type although the detent spring is slightly unusual in that it uses two separately footed springs mounted one above the other. The resulting action of the escape wheel and roller however remains the same as in Earnshaw’s escapement.