Fine Swiss staybrite split seconds chronograph watch Circa 1940

Deck watch in a mahogany box
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A fine and rare Swiss staybrite steel keyless lever chronometer deck watch made by Ulysse Nardin in Le Locle, circa 1940. With a split 10th of a second chronograph and an instantaneous 15 minute register. A  polished case with an insulated electrical contact in the band at 9 o’clock. Hinged cuvette. White enamel dial with bold Arabic hours, an outer minute track, outermost fifths of second divisions with Arabic numerals, subsidiary seconds at 6 o’clock, an instantaneous 15 minute register at 12 and blued steel spade hands.
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A rhodium plated movement, Geneva striping decoration, 28 jewels, fast beating straight line lever escapement, cut bimetallic compensation balance, Breguet balance spring, swan neck micrometre regulator, the escape wheel arbour is fitted with a cam allowing for breaking electrical contacts every fifth of a second via a lever activated by a bolt at 6 o’clock. Dial, case and movement signed.
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Diameter: 64 mm
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Signed: Ulysse Nardin  Le Locle
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Accompanied by the original mahogany three tier deck box with electrical contacts.
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The present watch is calibrated so that 30 seconds are recorded in one revolution of the chronograph hand instead of the usual 60 seconds. 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.