Large German stainless steel lever deck watch Circa 1920

Deck watch with Guillaume balance and timed in 9 positions by Hartmann
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Very fine, rare and large German stainless steel keyless deck lever chronometer with Guillaume balance and timed in 9 positions, circa 1920. Made for Observatory timing contest. Rhodium plated movement, 17 jewels, straight-line lever escapement, anibal brass Guillaume balance reglage 9 positions, blued steel Breguet balance spring, index regulator. White enamel dial with painted dauphine numerals, outer minute track, large subsidiary seconds and original blued steel spade hands. Polished case, screwed down bezel and back cover.  Dial signed, case and movement numbered.
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Diameter: 60 mm
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Signed: Johs Hartmann Berlin
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It is highly likely that this watch passed through an Observatory timing competition.