1941 Hamilton Model 23 Navigational Chronograph pocket watch made for the US Army Air Forces.

It was paired with the US Navy Model IV Octant, an aircraft Sextant introduced in 1941. See the Life Magazine advertisement the Model 23 clipped to the side of the Octant.

The watch second hand is at 6 o’clock position. The Chronograph big central seconds hand and the register at 12 o’clock records up to 30 minutes.

You push the button on the pendant to start/stop the Chronograph, pushing it a third time will reset the hands to zero.

The Hamilton Watch Company was an American company that was incorporated in 1892. In 1971 it became the third company of what was later to become the Swatch Group, the worlds largest watch manufacturer and dealer.

During the expansion of the railroads in the U.S., Hamilton maintained over 56% of the market. Railroads purchased all of Hamilton’s production. As the market switched from pocket watches to wrist watches after World War I, the company manufactured wrist watches.

During World War II, Hamilton retooled its business model to serve the military and production of consumer watches was stopped. With all watches manufactured being shipped to troops, more than one million watches were sent overseas.

The company also was extremely successful in producing Marine Chronometers and Deck watches in large numbers to fill the needs of the United States Navy, and other allied navies.