Large Swiss rose gold keyless lever chrono-tachymeter Circa 1910

Rose gold chrono-tachymeter
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A very fine and very rare, large-size Swiss rose gold chronograph keyless lever pocket watch with a 15-minute register and Omega’s patented (CH) multicoloured tachometer scale No. 8760 for determination of any speed up to 200 km/h, circa 1910. Frosted gilt 3/4 plate movement, 15 jewels, straight-line lever escapement, cut bimetallic compensation balance with a blued steel Breguet balance spring, swan-neck micrometre regulator, the chronograph work is set on a separate plate fastened to the back plate. Hinged gold cuvette. White enamel dial with Arabic numerals, outer minute and fifths of a second divisions, a sunk 15-minute register with five coloured zones corresponding to the colours of the outermost tachometer scale, running from 10.5 to 200 km/h and rose gold spade hands. A polished case, the engine turned back with a central circular polished medallion. Dial signed, case signed and numbered.
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Signed: Omega Cadran Breveté S.G.D.G.
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Diameter: 61 mm
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This timepiece is the largest and most complex of the Chrono-tachymeter watches by Omega and is extremely rare in a gold case. The term Chrono-tachymeter 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, 200 kph. The 15-minute counter includes five coloured zones corresponding to the colours of the tachymetric scale and indicates which sector of the scale is to be read. 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. Cal(ibre) 19”’ LOB, L = Lépine, O = Omega, B = 15-17 jewels, the Breguet balance spring adjusted to less than one minute per day.