OMEGA REF. 568.18 LARGE EARLY AVIATOR'S SINGLE BUTTON CHRONOGRAPH Omega, movement No. 4679520, case No. 5705986, Ref. 568.18. Made circa 1915. Very fine and extremely rare, large and early, silver wristwatch with single-button chronograph and register. Four-body, solid, pink gilt olive-shaped pusher at 6 for the start/ stop and return-to-zero functions of the chronograph, downward curved wire lugs, hinged caseback. Hinged silver cuvette. White enamel with black Arabic numerals, outer minute/ seconds and 1/5th seconds divisions, subsidiary dials for the constant seconds and instantaneous 15-minute register. Gold spade hands. Notes An excellent example of one of the earliest Omega chronographs in extremely good condition. This model marked a milestone for Omega as it was the fi rst generation of chronograph wristwatches ever made. It uses the famed caliber 18 that was used continuously from 1906 until 1928. Its large size made it ideal for aviation use.The present watch is very similar to the Omega owned by Lawrence of Arabia and sold by Antiquorum in November 2000 for a record sum at the time of 86,000 Swiss Francs. For similar examples see : Omega, A Journey ThroughTtime by Marco Richon, p. 525.