Patek Philippe 1518J An exceptionally fine and rare 18K yellow gold perpetual calendar chronograph wristwatch with moon phases. Cal. 13''' nickel-finished lever movement, 23 jewels, bimetallic compensation balance, silvered matte dial, applied yellow gold Arabic numerals, yellow gold feuille hands, outer railway Arabic five minute divisions, three subsidiary dials for constant seconds, 30 minutes register, moon phases and date, two windows for day and month, large circular case, extended down turned lugs, snap on back, two rectangular chronograph buttons in the band, case, dial and movement signed 35 mm. diam. manufactured in 1948 sold in 1950. Only 281 pieces were produced from 1941 – 1954. This series was the first to combine a perpetual calendar with a chronograph. This is an important piece, rare and very collectible .