English one minute tourbillon pocket chronometer Circa 1912

Gold tourbillon watch with power reserve
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A fine, very rare, large and heavy 18 carat gold keyless pocket chronometer with a one minute tourbillon and 30 hour power reserve submitted to the Kew Observatory trial in 1914, achieving 90.6 points made by S. Smith & Son in London, England. The solid and polished case is London hallmarked for 1912-1913, has an engine turned back, bears maker’s mark SS for Samuel Smith, has a bolt to engage the winding at 11 o’clock and one at 1 o’clock for the hand setting, and a hinged gold cuvette. The white enamel dial has Arabic hour numerals, an outer minute track, subsidiary seconds at 6 o’clock, a 30 hour power reserve indicator at 12 and blued steel spade hands. A ½ plate movement with fusee and chain, jewelled escapement, one minute equidistant arm tourbillon carriage after Nicole Nielsen, a lateral polished steel bridge, English lateral lever escapement with lift on the pallets, Guillaume balance with gold and platinum temperature and meantime adjustment screws, and free sprung blued steel balance spring with Phillips outer terminal curve.
Movement signed and numbered, case numbered.
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Diameter: 57 mm
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Signed: S. Smith & Son
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S. Smith & Son was the leading London firm for high quality and complicated watches at the end of the 19^th century and during the opening decades of the 20^th.  The company was founded by jeweller and watchmaker Samuel Smith circa 1851. Watches were made for him by Nicole Nielsen. Alongside the wide range of civilian watches and clocks, Smith’s also made chronometers which performed well and made the firm a supplier to the Admiralty. Under the guidance of Herbert S.A. Smith, the firm developed into a large manufacturing company with its own research laboratories, the family succession being continued a further generation by Sir Alan Herbert Smith expanding production with automobile and aircraft instruments alongside clocks and watches.