English one-minute tourbillon lever with power reserve Circa 1912

Gold chronometer by S. Smith & Son
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A fine and very rare English 18 carat gold open faced keyless lever pocket chronometer with one-minute tourbillon regulator and 30-hour power reserve indication, Kew Observatory trial 1914, 90.6 points, the case with London hallmarks for 1912- 1913. Half-plate movement, fusee and chain, jewelled escapement, one-minute Nicole Nielsen equidistant arm tourbillon carriage, lateral polished steel bridge, English lateral lever escapement with lift on the pallets, Guillaume balance with gold and platinum temperature and meantime adjustment screws, free-sprung blued steel balance spring with over coiled Phillips outer terminal curve. Gold hinged cuvette. White enamel dial with Arabic numerals, outer minute track, subsidiary seconds, 30-hour power reserve indicator at 12 o’clock and original blued steel spade hands. Solid, polished case by Samuel Smith, master mark SS, solid, polished, engine-turned back, bolt at 11 to engage the winding, at 1 for the hand-setting. Movement signed, case numbered.
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Diameter: 57 mm
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Signed: S. Smith & Son 9 Strand London Makers to the Admiralty and the Indian Government Grand Hotel Buildings Trafalgar Square London