Exceptional Swiss gold one-minute tourbillon watch Circa 1930

Gold open faced lever pocket watch
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An extremely fine and exceptionally rare Swiss, extra-large, 18K yellow gold keyless pocket watch, circa 1930. Lever chromometer with extra quality movement, one-minute regulator by J. Golay-Audemars, adjustment by Golay-Audemars, Guillaume balance, a first prize winner at the Observatoire de Geneve contest, 1929, category A. Re-tested in 1959, regulated on this occasion by Andre Zibach. Accompanied by the Extract from the Archives and the Bulletin de Marche of 1959.
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A polished, concealed hinge. Hinged gold-rimmed glazed cuvette. Matte silver dial with applied yellow gold faceted baton indexes, outer minute divisions, subsidiary seconds. Yellow gold Dauphine hands. A rhodium-plated movement, Geneva striping decoration, 18 jewels, one-minute tourbillon regulator by Golay-Audemars, three equidistant arms polished steel cage and bridge, calibrated and counterpoised lateral lever escapement, Guillaume cut Anibal-brass compensation balance with winged arms, adjusted to heat, cold, isochronism and five positions, 18 gold peripheral temperature adjustment screws, blued steel Breguet balance spring, index regulator. Dial, case and movement signed.

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Diameter: 60 mm
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Signed: Patek Philippe & Co.  Geneva
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The present watch was submitted for trial at the Observatoire de Geneve in 1929, category A, achieving the following results: 849 points out of a possible 1000 – first prize. While this chronometer obtained the first prize with 849 points, the last one classified obtained 601 points. It ranked first out of 98 watches examined. It was tested with a compensation error by Centigrade degrees of 0.018, and reprise demarche of +0.20. It was submitted again for testing in 1959 and was regulated by Andre Zibach. The inscription Extra on the bridge of the movement refers to the high finishing of all the parts of the movement. The present lot is accompanied by a copy of the Geneva Observatory chronometer contest of 1929. Literature: Das Tourbillon, Reinhard Meis, Verlag Laterna Magica, 1986.