Rare and important Swiss gold complicated watch Circa 1917

Open faced complicated watch by Patek Philippe
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A rare and important Swiss 18 carat gold open faced miute repeating perpetual calendar split seconds chronograph keyless lever watch with half instantaneous thirty minute recorder, moon phases and rare tinted white enamel dial, circa 1917. Nickel finished lever movement, 39 jewels, bimetallic compensation balance, micrometer regulator, minute repeating on two gongs activated by a slide in the band. Later gold cuvette. Tinted white enamel dial with Roman numerals, outer calibrated fifth seconds ring, Arabic fifths divisions, blued steel moon hands, four subsidiary dials for day and month in English, date combined with constant seconds and 30 minute register combined with phases of the moon and lunar calendar. Plain heavy case with invisible hinge, split-seconds chronograph buttons in the band and in the crown, both locked by a sliding lever in the band. Case, cuvette, dial and movement signed.
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Diameter: 55 mm
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Signed: Patek, Philippe & Cie Geneva Switzerland