Yellow Gold Ref. 1518, 1st Series with Cyclops Lens Patek Philippe, Genève, movement No. 867236, case No. 649553, Ref. 1518, 1st series.Made circa 1947. Very fine, important, and extremely rare 18K yellow gold wristwatch with square button chronograph, register, perpetual calendar, moon phases, tachometer and an 18K yellow gold buckle. Accompanied by the Extract from the Archives. Three-body, solid, polished and brushed, concave bezel, concave lugs, snap-on case back, crystal with cyclops lens. Matte silver with applied yellow gold Arabic numerals and dot indexes, subsidiary dials for the seconds, 30 minute register, for the days of the month, apertures for the days of the week and the months at 12, aperture for the moon phases at 6, outer minute and 1/5 seconds track with five Arabic numerals, outermost tachometer scale. Yellow gold feuille hands. 13, rhodium plated, fausses cotes decoration, 23 jewels, lever escapement, bimetallic balance adjusted to 8 positions, self-compensating Breguet balance spring, index regulator. Dial, case and movement signed. Diam. 35 mm. Thickness 14 mm. Notes To the best of our knowledge this is the first Ref. 1518 with cyclops lens to be offered at auction. Ref. 1518 is a masterpiece among watches, with perpetual calendar and chronograph. It inspired the famous fourth series of reference 2499, the 2499/100, then references 3970 and 3971, and the newcomer, reference 5970.