French platinum split-seconds lever chronograph Circa 1922

Platinum dress watch with chronograph and register by Cartier
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A very fine and extremely rare French platinum open faced split-seconds chronograph lever dress watch with progressive 30-minute register, one of only two known examples of this model in platinum, circa 1922. Frosted gilt movement, 23 jewels, straight-line lever escapement, cut bimetallic compensation balance, blued steel Breguet balance spring with overcoil, index regulator, visible steel chronograph work. Matte silver dial with champlevé dauphine numerals, outer minute track with Arabic five-minute numerals, outermost fifths of a second divisions, subsidiary dials for the seconds and the progressive 30-minute register, original blued steel Breguet hands. Polished case, curved inclined bezel, coin-edge band, reeded bow, button between 10 and 11 for the split-seconds, button in the crown for start/stop of the chronograph. Dial signed, case numbered. Accompanied by a Cartier box.
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Diameter: 49 mm
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Signed: Cartier Paris
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Split-seconds dress watches by Cartier are extremely rare and were made in very small numbers in the early 1920s. The movements were made either by the European Watch & Clock Co or by Audemars Piguet, who also made another much later series of such watches for Cartier in the 1950s.