ive been wondering about the history of my model 21. Is there a way I can tell what this clock did during its lifetime? The dial is marked N869. Just curious.. Thanks for any help.

Bruce

The N in the number - is it in a circle? I assume it likely is and if so it is the marking of the US Naval Observatory. The USNO was the receiver of marine chronometers and they tested them before issuing them to ships in either the US Navy or the Maritime Commission or the Army Air Force. The number after the N in a circle would be the USNO's consecutive serial number for that particular Model 21. Whitney says that during WW 2 Hamilton delivered to the USNO 13,087 marine chronometers of which 8,902 were issued to the US Navy, 1,500 went to the Maritime Commission, and 500 went to the Army Air Force.

My guess is that a large majority of these are still around given that whenever they needed repair or overhaul they were returned to the USNO who did the work and sent them back to whatever ship they came from or reissued them to another ship. After the war many were surplussed to the public and eventually all were surplussed and given how nice they are they are the sort of timepiece that owners had repaired rather than disposing of them.

When they were issued to a ship there was a paper record sheet that was kept with the timepiece, including being kept with the timepiece when they were sent back to the USNO for repairs or overhauling. Those record sheets would show which ship they were used on and during what years.

Others here are more expert on these timepieces than I am as to whether there are some kind of master records still existing for all of these marine chronometers other than the individual papers that accompanied each one. So far I have not heard anyone say there is such a master record though I would very much like to know for sure if someone does know.

Bruce, Your best chance of success would be to visit the National Archives in the Navy Department, Bureau of Ships, or the U.S. Naval Observatory. The Hamilton Model 21 was accompanied by a "Ship's Chronometer Record" that was maintained by the Quarter Master. About every ten days, the QM would record the mean daily rate, and the conditions the vessel was undergoing. For example, how many days days the ship was underway, and the sea conditions that would have an effect on the daily rate. (Marvin Whitney, The Ship's Chronometer, page 39)

I was also able to find the original Hamilton Chronometer Trial Record Card of my Model 21 when I visited the Museum in Columbia, PA. It's not far from the Hamilton factory location in Lancaster, PA, and this is where a large amount of Hamilton records are stored. Each chronometer was tested for accuracy before being delivered to the Government. The Naval Observatory did further tests before acceptance of each Model 21.

Serial number (N)869 was delivered to the government about June-July 1943. (Whitney, page 51) This may help you in your research if you are able to visit the National Archives, or the museum in PA. Keep in mind that the Naval Observatory came up with a modification to easily capture the balance wheel for shipping without having to "cork" the balance. They also developed an aluminum chronometer shipping container where the chronometer–without the gamble and box– could be mailed to the Naval Observatory for periodic service. It was a one-for-one swap, so the chronometer may have circulated between several ship's or placed in stock.

Matthew and Jim.... Thank you for the info. I just finished corking my Russian box chronometer for my future move to Washington state. I fired up my model 21 and am waiting for it to hit the half way point so I can capture the balance ( great idea Hamilton had for securing the balance). Both of these chronometers are extremely accurate (the 21 after not being run for a year was 2 seconds slow after 24 hours. The last 24 hours was running about 1/2 second slow.. I'll take that from a 70 + year old chronometer... The Russian one after a year was 1 second slow. My second full wind has it still running the same).

Thank you both for the insight.