Rare French silver keyless lever pocket watch Circa 1920

Silver watch in original Breguet Morocco leather box
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A very fine and very rare French, silver and gold, keyless lever chronometer for Besançon Observatory Timing Contest, circa 1920. Split-seconds chronograph, 30-minute register and the original Breguet Morocco leather-covered box. Accompanied by a certificate. A massive, polished case with yellow gold split-seconds button and setting pin surround. Hinged silver cuvette.
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White enamel dial, radial Arabic numerals, outer minute and fifths of a second division with five-minute Arabic numerals, subsidiary dials for the seconds, 30-minute register at 12 o’clock. Gold spade hands. A frosted gilt movement, 24 jewels, stamped with the Besançon viper’s head mark, straight-line lever escapement, cut bimetallic compensation balance, blued steel Breguet balance spring, index regulator, chronograph and split-seconds mechanism set on the back. Dial and cuvette signed. Property of a French Gentleman.
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Diameter: 55 mm
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Signed: Breguet  Paris
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The viper’s head was the official Besançon Observatory punch mark. The more complicated a timepiece is, the more difficult it is to adjust, particularly with complications such as a chronograph, split-seconds function, and/or a register. The additional wheelwork affects the timepiece’s functioning, because of the amount of energy required but often only sporadically, when, for example, the chronograph is in use and because of the friction to which the moving parts of the mechanism levers, springs, etc. are subjected.