Large Swiss silver open faced lever pocket watch Circa 1920

Silver keyless pocket watch
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A Swiss silver open faced keyless pocket watch by Zenith, Le Locle, circa 1920. A solid, polished, plain case back. White enamel dial with suspended Arabic numerals, outer minute track, subsidiary dial at 6 and 12 o’clock and gilded metal hands. Alarm on a steel gong, subsidiary dial at 12 o’clock with blued steel index, time setting by push pin on the right side of the pendant. Twin barrel differential winding. A gilded brass, ½ plated movement, two going barrels, straight line lever escapement, cut bimetallic compensated balance and blued steel hairspring with terminal curve, polished steel index regulator. Signature on the case and movement.
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Diameter: 79 mm
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Signed: Zenith  Le Locle
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Accompanied by a copy of the invention patent.
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The hinged case back, once deployed, serves as a base for the watch to stand on a nightstand or on a desk. Movement based on the Swiss invention patent No. 63 623, delivered on March 11, 1913, to Fabriques des Montres Zénith, successeur de Fabriques des montres Zénith Georges Favre-Jacot & Cie, Le Locle, for a Montre-réveil perfectionnée.