German nickel deck watch with power reserve Circa 1940

Nickel 0pen faced deck watch
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A fine German, keyless, nickel deck and pocket lever chronometer with power reserve indication and special balance by A. Lange & Söhne  Glashütte, circa 1942. Made for the Kriegsmarine Observation Service. The back cover engraved with the Observation Service number. Hinged stainless steel cuvette. Brushed, silvered dial with painted black Dauphine numerals, outer minute track, subsidiary seconds at 3, power reserve indication at 9. Blued steel spade hands. Frosted gilt movement, three-quarter plate, 17-jewels, straight line lever escapement with lateral banking extension on the entry pallet, Guillaume balance, blued steel Breguet balance spring with patent stud fastening, swan-neck micrometer adjustment to the regulator. Case, cuvette and movement signed.
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Diameter: 60 mm
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Signed: A. Lange & Söhne Glashütte i/SA