#LONGINES SERIAL NUMBERS AFTER 1969 SERIAL NUMBER#

Pending.īelow is an earlier model without the patent pending addition to the dial.Īnother Vanguard conversion with the second setting at 1 o’clock, with an article from a Motor Boating magazine. Waltham Vanguard pocket watch, dial marked Weems Pat. These watches were initially converted in larger numbers by Louis Levin and Sons in California, but later in house by the Navy.īelow is a Weems Aero-chronometer, adjusted 27 November 1928 by Louis Levin, with an adjustable second setting dial at 6 o’clock, and a power reserve indicator at 12 o’clock.

Lincoln Ellsworth, the polar explorer, has the Number One commercial second-second setting watch, designated by Jessops as the “Aero Chronometer”.” The hour and minutes are set in the usual manner.” A small arm,on the left side of the watch,operated by the finger nail moves the dial from one to three seconds per stroke,making it a simple matter to set the exact second. In each case the second dial was cut out, and a movable dial mounted on a ratchet wheel with sixty teeth was inserted. A slightly different alteration was made on the watches, since they are not similar in construction. The details of altering these watches was worked out with Mr. They were altered to permit the exact second to be set. “The first two Weems watches were torpedo boat watches one Hamilton rated to mean time and a Patek Philippe & Cie. Navy, June 1928 issue of Proceedings USNI Magazine wrote : In 1927 the US navy started converting surplus war stock patrol boat chronometers to accept his simple modification to develop a “hack” watch. Weems decided that it would be sufficiently accurate to avigate with a good quality watch which could be easily reset to radio time signals, rather than attempt to carry a delicate marine chronometer in the air. Weems determined that it was essential to simplify aviation navigation computations, and to develop fast, reliable methods of navigation that were simpler than maritime techniques, even if slightly less accurate.Īlthough radio beacon navigation improved rapidly in the 1930’s, this was rendered marginally operable in WW2, and onboard navigation computations using Weems systems were necessary for most of the WW2 period.Ī vital stepping stone in advancing both marine and air navigation was the Weems Second Setting watch. In the middle 1920’s pilots were being killed crossing the oceans, as avigation was not easy, so Weems expanded his naval experience to the needs of pilots.īy the early 1940’s the Weems System of Navigation course trained many military aviation navigators, and marine navigators, using the books and equipment that Weems had developed and used earlier for commercial navigation. Modern air navigation is strongly influenced by the work of Philip Van Horn Weems, who worked on all aspects of what was then called avigation. This article will discuss the development of the Weems rotating bezel up to about 1940 when the military versions of the second setting watch were introduced.

3346 which also featured a rotating bezel, but this dates to 1937, and was never made available for public sale.Ī possible even more distant third is the Glycine Airman patent 314050 of 1953, registering a rotating 24 hour bezel and a bezel lock at 4 o’clock. Perhaps a distant second is the 32mm diameter Rolex Zerographe ref.

#LONGINES SERIAL NUMBERS AFTER 1969 SERIAL NUMBER#

It is the design drawing for Longines serial number 5145705 with Breguet hands, and is related to his patent application of 1929 which encompassed a rotating bezel. The model featured above is from about 1930. The answer is the Weems, with what the advertising initially called a rotary verge ring. The question has been asked “Which watch carried the first rotating bezel?” WRIST MODEL SPECIAL BEZEL – ROTARY VERGE RING.

Longines serial numbers after 1969