Swiss silver pocket chronograph with tachometer Circa 1903

Silver open faced lever by Omega
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A fine and rare silver keyless pocket watch with chronograph, circa 1903. A 15-minute register and Omega’s patented (CH) tachometer scale. The case with an engine-turned back. White enamel dial, radial Roman 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 140 km/h. and blued steel spade hands. A frosted gilt movement, 3/4-plate, 15 jewels, straight-line lever escapement, cut bimetallic compensation balance with Breguet balance spring, swan-neck micrometre regulator, the chronograph work is set on a separate plate fastened to the back plate. Dial signed. This watch is sold with a box and certificate of authenticity.
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Diameter: 54 mm
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Signed: Omega Cadran Brevete S.G.D.G.  Swiss
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The case is slightly rusted.
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The present watch was called a Chronotachymetre by Omega. This term refers to the dial with its extended tachymeter scale capable of timing speeds both slow, 10.5 kph, to speeds that were not yet achieved by the fastest cars of the day, 140 kph. Most tachometers from this period that graduated to such high numbers were marked UPH as they were more commonly used for production timing. At the time this watch was made such speeds were encountered only in scientific experiments as aviation was in its infancy. This type of dial could be found on both wrist and pocket chronometers from this period. Breguet balance spring adjusted to less than one minute per day.