A similar watch is published in Longines, p. 82. This watch is very rare and very special. It was one of the models which were sold by the American Forces to the Japanese Air Force in 1933. The dedication on the case back says: "Air Force, No. 467". This hour angle system is called the "Weems Model" because of its Inventor: Professor and Instructor Philippe Vanhorn Weems, of the Naval Academy of Annapolis, who was an authority in the 1920-30's. He formed the famous Charles A. Lindbergh who established the record for the first non-stop transoceanic flight. The hour angle watch "Lindbergh Model" used for this flight, is drawn from the Weems invention. Professor Ph. Weems wrote several important books and received a Gold Medal from the International Aeronautic Federation. This watch bears a large ball-shaped winding-crown, enabling the watch to be rewound by a pilot whilst wearing gloves. It is practically impossible to build a commercial timepiece which will keep time to the exact second under the conditions met in a ship or in an airplane. The unavoidable variation in the chronometer from true time has necessitated an extra calculation in navigation to compensate for this chronometer error. Lt. Commander P. V. H. Weems, US Navy, noticed that in an airplane moving at speeds of 200 to 300 miles an hour or more, the time required for calculating chronometer error was a hazard that should be eliminated. Since it is impractical because of high gear ratio to set the second hand to the dial, Commander Weems hit upon the idea of setting the dial to the hands. The seconds dial in the center of the large watch is rotated by crown by depressing the small stem. Use: the hour and minute are set on the watch in the usual way. For navigation purposes, the Greenwich Civil time is set directly on the watch face. When being set with a radio time signal which comes in on the minute, the second dial is rotated to keep the 60 mark continuously under the second hand. The dial is stopped the instant the signal is heard. For serious navigation, a record should be kept of the errors and of the daily rate as indicated by movement of the second dial. The Longines Weems Second- Setting Watch is made in two styles. The smaller model is useful not only for sea navigators and aircraft pilots, but particularly radio broadcasters as well as others, such as civil engineers who require exact time.