I obtained this item at an Estate Sale, but I have no idea as to what it is. The Hamilton Model is 4992B, the serial number is 4C20179. It is a 22 jewel 16s movement and for the US Govt. I know that this watch movement is a highly desirable piece. Based on the serial number this movement was made in 1940.

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That appears to be a movement for an Airman's pocket watch.

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That was what someone at the Estate Sale Suggest, however, he had no idea of what this item (Complete as it Now is) is. Do you have any idea what this completed item is? Thanks for your reply.

That watch movement is graduated in minutes and seconds in the Decimal Minute Second System. It also has a standard hour, minute, second face.

It was used by aircraft navigators flying long distances and by astronomers in their repeated observation of a particular spot in the sky. Both uses were before the advent of computers and the GPS system. That particular watch work was installed in the plexiglas holder for mounting on a plot board on the aircraft navigator's desk. It was found that navigators made far fewer mistakes while using the DMS system in plotting position to position of the aircraft.

An aside; there were many efforts by mainly so called scientist way back in history to change the 24 hour, 60 minute, 60 second measurement system of time. Most wanted to decimalize the hours, minutes and seconds. One or two actually wanted to decimalize the year. None of these systems were ever very popular. The very powerful religions of the time didn't want and wouldn't allow the change.

Hey Brother, I truly appreciate your insight and expertise on this item. I was really at a loss, I didn't even know what to do a search for. This is very interesting information!

Looking at the chart here: Vintage Watch Forums • View topic - Hamilton Watch Company Data it could be from 1941

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There is a national organization called NAWCC (National Association of Watch and Clock Collectors). I think they can answer questions like this, or refer you to who can, if you contact them. Welcome to the NAWCC!

BTW, I have a 1943 Hamilton Model 22 cased marine chronometer watch, but I think its movement is considerably larger than yours.

I am a paying member of the watch club IHC185 you can find them on the internet they have a great section on each of the american watch companies. I have only seen one of 4992's in person they also have a page where you can buy cases and I have seen one or two there over time for sale, they are wonderful movements and from the late 1800.s until the very early 1950's we built the finest pocket watches in the world. Jeff

Thanks for your input. Yes, the 4992 movement is very rare, at least that's what we have been told. I do not know this as fact, but from what we have been told, the 4992 movements were made only in 1940 & 1941. ??? The one I have, based on the serial number, appears to have been made in 1940.

we collect 992B's... but only have 1 of the USGI stainlesssteel cased ones.. it basically was a gift from another watchmaker who was close friend of my dad, a watchmaker too. I'm leaving it to one of my daughters for her to pass on. This variation is far more uncommon than the normal 992B's Rail Road watches. The 992B's are the most accurate mechanical watch ever made... often surpassing the modern quartz movement watches. One of the guys just posted a great site on it.. unfortuneately I fried that computer just before I fell & broke my femur near 2 weeks ago.

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I am going to meet 'johnnyflake' this coming Wednesday for coffee. I am going to have along with me my father's Hamilton Railway Special 992B. It had sat on the Jewelry store's shelf for quite a while because I traced it back to 1940 manufacture date. He bought it new in Las Vegas in early 1944 when he went to work for the Union Pacific Railroad as a Fireman. He checked out as an Engineer in late 1945, but the returning Vets had seniority and that got him bumped back to Brakeman. So, he quit and went back to construction. ......

Here's that 992B link: Hamilton 992B Railroad Watch (1940-1969)