A Very Rare Early Oversized Single Push Chronograph Aviator's Wristwatch, signed Omega, ref: 568.18, Omega Museum confirms this watch was manufactured in July 1915, (calibre 18''') frosted gilt finished lever movement signed and numbered 4428352, bimetallic balance with blued overcoil hairspring, white enamel dial with Arabic numerals, outer minute and fifths of seconds tracks, two dials for seconds and 15-minute register, single push pink gilt button below 6 to operate red chronograph hand, wire lugs, nickel case with hinged back stamped inside Omega and numbered 5415908, cuvette with matching number, 46mm wide, see illustrations This watch is sold with an email from the Omega Museum's vintage watch specialist' John R.Diethelmm. He confirms that this watch is recorded in the Omega archives, stating the case and movement numbers, movement calibre and watch reference and that the watch was manufactured in July 1915. This is an excellent example of one of the earliest Omega first generation model chronographs ever made. This watch uses the calibre 18''' which is a pocket watch size movement. Its large-size case and clear visible enamel dial and ingenious design of chronograph button at 6 o'clock was ideal for pilots to read the time and activate the complication during flying. Similar oversized single button chronograph wristwatches are illustrated in Goldberger (J) Omega Watches, pg.66-69. An almost identical wristwatch sold at Sotheby's New York sale October 19th 2007 lot 136 for $28,600. Another almost identical watch, owned by Lawrence of Arabia, sold at Antiquorum, Geneva sale, 11 November 2012, lot 557 for 86000CHF