Swiss deck watch chronometer for the US Navy Circa 1920

Silver open faced collector’s deck watch by Longines
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A rare Longines deck watch chronometer for the US Navy, with high-grade precision caliber 21.29, circa 1920.
Silver smooth case with matching numbers on case and movement. Very fine Ankerchronometer movement with separated 3/4 main plate and fine adjusting device, chronometer balance, lever escapement, adjusted in 8 positions, nickel-plated and Geneva stripes. Silvered dial with power reserve indication, subsidiary dial for the seconds and blued steel hands.
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Diameter: 68 mm
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Weight: 214 g
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Signed: Longines
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The caliber 21.29 was one of the most accurate chronometers in this time. It was also used in the extremely rare Longines siderographs. Normally, these Longines deck watch chronometers were equipped with the caliber 24.99.