Swiss silver lever deck chronometer pocket watch Circa 1940

Silver watch with chronograph split seconds
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A fine and unusual Swiss, Silver Staybrite, keyless circuit breaker lever deck chronometer watch, circa 1940. With split 1/10th second chronograph with two times 30 second revolutions, instantaneous 15 minute register and Guillaume balance. A polished case, insulated electrical contact in the band at 9 o’clock. Hinged cuvette. White enamel dial, bold Arabic numerals, outer minute track, outermost 10th of second divisions and Arabic 3 second numerals, subsidiary seconds at 6, instantaneous 15 minute register at 12. Blued steel spade hands.
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A rhodium-plated movement, Geneva striping decoration, 28 jewels, fast beating straight-line lever escapement, Guillaume balance, Breguet balance spring, swan neck micrometre regulator, the escape wheel arbour is fitted with a cam allowing for breaking electrical contacts every 10th of a second activated via a slide bolt at 6. Dial, case and movement signed. Property of an Italian Gentleman.
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Diameter: 64 mm
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Signed: Ulysse Nardin  Locle
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The present watch is very unusual as it is calibrated so that 30 seconds are recorded in one revolution of the chronograph hand instead of the usual 60 seconds per revolution. This is achieved by a fast beating escapement; the hour and minute hands are geared to operate in the usual manner. This chronograph was specially made to time events to a precision of 1/10 second. Breitling has recently used this system for its Breitling for Bentley range of chronograph wristwatches, as have De Bethune for their new chronograph.