Very early Swiss silver open faced chronograph Circa 1878

Silver chronograph by Longines
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An extremely rare and very early Swiss silver open faced chronograph pocket watch, circa 1878. Very early chronograph movement according to Lugrin’s patent type I. Cuvette inscribed Longines Chronograph Patd Sept. 28, 1880 Gold Medal, Paris 1878. White enamel dial with Roman hours and Arabic minutes, fine chronograph scale, subsidiary seconds, blued steel hands. Engine turned case, blanc cartouche on the back. Case numbered, movement signed and numbered, case and movement with matching numbers.
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Diameter: 53 mm
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Weight: 122 g
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Signed: Longines
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This piece is the first chronograph Longines made.