Swiss deck chronometer with two times 30 second revolutions Circa 1940

Split 1/10^th second chronograph with two times 30 second revolutions
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A fine, rare and unusual, ‘Staybrite’, keyless circuit breaker lever deck chronometer with split 1/10^th second chronograph with two times 30 second revolutions, instantaneous 15 minute register and Guillaume balance. Accompanied by the original numbered mahogany three tier deck box with electrical contacts. Made by Ulysse Nardin, Locle, Switzerland, Circa 1940. Four body, bassine et filets and polished case with insulated electrical contact in the band at 9 o’clock and a hinged cuvette.
White enamel dial with bold Arabic numerals, outer minute track, outermost 10^th of a second divisions and Arabic 3 second numerals, subsidiary seconds at 6 o’clock, instantaneous 15 minute register at 12 o’clock and blued steel spade hands. Rhodium-plated movement with Geneva striping decoration, 28 jewels, fast beating straight-line lever escapement, Guillaume balance, Breguet balance spring, swan neck micrometre regulator and the escape wheel arbour is fitted with a cam allowing for breaking electrical contacts every 10^th of a second activated via a slide bolt at 6 o’clock.
Dial, case and movement signed.
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Diameter: 64 mm
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Signed: Ulysse Nardin, Locle, Suisse
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This 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 used this system for its Breitling for Bentley range of chronograph wristwatches, as have De Bethune.