Hamilton，罕有，金屬美國海軍型號22 48小時精密時計，配雙盒子，約1943年製

Following entry in to World War II, the United States Navy required reliable timekeepers for their expanding fleet. With few chronometers available, the US Navy Observatory issued a challenge to watch makers to design and produce a high grade chronometer that met Navy requirements, including the ability to interchange parts and their immediate availability. The Hamilton Watch Company fulfilled the request with both the Model 21 with helical hairspring and the Model 22 like the present example. The Model 22 was housed in the typical gimbal mount or in the more rare version with the double wooden flat boxes. It is thought the large pocket watch format of the present example was used on smaller PT boats.