American gilt watch with Delong escapement Circa 1915-1920

Gilt American railroad watch by Hamilton Watch Co.
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A fine American railroad watch. Ball Watch Co. model Grade 999 Official RR Standard by Hamilton Watch Co., circa 1915-1920. 23 Jewel movement, concentric damascened divided ¾ plate, jewels in settings, Delong escapement with upright pallets, bimetallic balance, overcoiled spring, swan’s neck regulator, stem wound, lever set. White enamel dial with black Arabic numerals, subsidiary seconds and blued hands. 10 Carat gold filled plain open face case, signed ‘Wadsworth’.
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Diameter: 49 mm
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Signed: Trade Mark Official Standard Ball Watch Co Cleveland – Ball Watch Co. Cleveland, O. Trade MArk Official Standard