Swiss steel split seconds chronograph lever watch Circa 1910

Steel open faced lever chronograph by Ulysse Nardin
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An exceptional and rare Swiss open faced split seconds steel pocket chronograph lever watch with an instantaneous 15 minute register, circa 1910. Known as Chronographe Rattrapante Chronomètre. This watch features a handwound mechanical rhodium plated movement with lever escapement. It has a white enamel dial with a black painted minute track and Arabic numerals, blackened steel Poire hands, perpetual seconds at 6 o’clock, a 15 minute totaliser at 12 o’clock, and a double central second hand for chronograph and split seconds functions. The plain steel case has a smooth bezel, fluted crown, round bezel, and double case back. It comes with a period mahogany case with a key. The case, dial, and movement are signed.
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Diameter: 62.3 mm.
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Signed: Ulysse Nardin Locle – Suisse Chronomètre
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In excellent condition, with minor scratches from use, this is a museum quality watch.
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A split seconds chronograph, or ‘rattrapante’, is a type of chronograph watch with two coaxial superimposed centre seconds hands that are controlled by two push buttons. One push button controls the split seconds hand to stop or join the chronograph hand. The other push buttons control both hands and all the chronograph functions. The chronograph and split seconds hands are used for timing several events that start simultaneously, but are of different durations. To operate the split seconds chronograph, both hands are started and remain superimposed. Then at the end of the first duration, the split seconds hand can be stopped while the chronograph hand continues to move. The duration of the first event can be read. After recording, the split seconds hand can be released to instantly move and join the chronograph hand, synchronising with it and thus being ready for another recording. At the end of each event, the hands can then be stopped and returned to zero. The split seconds chronograph, in its present form, was first introduced in 1880. Split seconds chronograph wristwatches came on the market circa 1922 by Patek Philippe (the first known wristwatch of this kind was Patek Philippe No. 124824, case No. 235326. This timepiece appeared five years prior to the official release of the split seconds chronograph, making Patek Philippe the first manufacturer to create this complication in a wristwatch. As they require a highly complicated and technical mechanism, these watches are desirable, very collectable and extremely difficult to produce, accounting for their rarity.