Swiss gold watch made for the English market Circa 1850

Gold open faced chronometer watch
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A fine and rare Swiss 18K gold pocket chronometer with unusual banking for the detent by William Mottu, Geneve, made for the English market, circa 1850. Engine-turned and polished hinged gold cuvette, master mark PM. White enamel dial with radial Roman numerals, outer minute track, subsidiary seconds. Blued steel hands.

Frosted gilt, half plate movement, fusee and chain with Harrison’s maintaining power, Earnshaw type chronometer escapement with spring footed detent, spring footed banking arm parallel to the detent, cut bimetallic compensation balance with gold temperature and meantime adjustment screws, free-sprung blued steel helical balance spring, diamond endstone. Dial and movement signed.
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Diameter: 48 mm
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Signed: William Mottu Genève
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Mottu a well-known family of watchmakers working in Geneva in the second half of the nineteenth century, known, among other things, for supplying movements to E.J. Dent in London. Ad. Mottu, 131 rue des Etuves. 1830 – 1831, was an eminent finisher and maker of balance- springs. At the Geneva Exposition in 1828, he presented a series of spherical balance springs, and in 1829 he signed a petition for the construction of a new observatory.