Hamilton, 4992B, United States Air Force Navigational Master Watch GCT, 22 jewels, adjusted six positions. 16 size, Elivar extra hairspring. Circa 1958. Made in Lancaster, Pennsylvania, USA. Hack setting (stem pulls out to stop second hand). Military nomenclature on back.
In this particular example, the dial and movement are excellent. The case is in very good condition with a very slight spot of nickel silver showing through on the center of the back (<3mm). Original plastic crystal has an aged, attractive milk color to it from age.
The 4992B is based is a slightly modified version of Hamilton’s famous 992B which was developed for use in the railroad industry in the United States and is probably one of the finest mass-produced pocket watches ever produced. It was introduced in 1940 and billed as “America’s finest and most accurate railroad watch.” The 4992B is the same design but modified with a sweep second hand that could be stopped for synchronization and had a 24-hour dial which was important when operating in areas all around the globe.
These timepieces were used by the navigator and pilot as the airplane’s master time source during World War II through Viet Nam era (today’s Navigational timepiece can be found here: Marathon Navigator Watch). It was intended to be set to Greenwich Civil Time (GCT) as a reference timezone. Late 1950’s pieces were carried by Navigators aboard B-52 long-range bombers as seen in the Movie, Dr. Stangelove.
A Nice example of a Cold War era Navigational Master Watch GCT from US Air Force.