Rare Swiss silver pocket watch with chronograph Circa 1930

Silver open faced lever pocket watch
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A fine and rare silver keyless pocket watch with chronograph 15 minute register and tachometer by Omega, Bienne, Switzerland, Circa 1930. A polished case, open faced single button chronograph pocket watch. White enamel dial with Arabic numerals, outer minute seconds divisions divided into fifths, sunk 15-minute register, the first five minutes in different colours corresponding to the colours of the outermost tachometer scale, running from 10.5 to 180 km/h and blued steel spade hands. Frosted gilt, 3/4 plate movement with 15 jewels, straight line lever escapement, cut bimetallic compensation balance with Breguet balance spring, swanneck micrometre regulator and the chronograph work is set on a separate plate fastened to the back plate. Dial and case signed.
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Diameter: 54 mm
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Signed: Ω Omega Cadran Brevette S.G.D.G.  Bienne