I have a traditional Marine Chronometer as well as what is likely the best chronometer ever, a Hamilton Model 22 (complete with interesting history and provenance) but it's the Waltham that fascinates me most. I think that's because there is surprisingly little detailed information on them. On the other hand, there are lots of little mysteries surrounding them. In my small collection of four - two "born" and two "drafted" (as Tom McIntyre puts it) ranging from 1910 to 1940 - I notice differences that are intriguing.



(#18072577) is a private label Bigelow Kennard travel clock listed in the Gray Book as "chrono" grade dating to 1910. This one has (what might be the definitive "born" feature) a diamond end stone, but oddly no micrometer regulator. It also features screw set jewels, which must be an early arrangement that was soon discontinued. Does anyone know the details about this?



(#19042611) is a "born" boxed/gimbaled Crono and dates to 1913. This one has the later jewel setting, and the typical micro regulator, but sports an actual 8-day wind indicator rather than the red dot type. Does anyone know why the two types and when the graduated wind indicators were used - then discontinued? Was this an "intermittent" feature for all "chrono" grades or was it exclusive to the navy or what?



(#17835612) is the most intriguing because this old timer from 1910 appears to be a "drafted" conversion done during WWII, and has an added Hamilton 992B-style micro regulator, lives in a gimballed tub but has no box. It is simply attached to a homemade board mount and also dates to 1913, but obviously was not "Chrono" grade when new. I strongly suspect this was one of many privately owned 8-day watches converted for war demands. The fact that it was probably 30 years old at the time sure seems to underscore how critical the need was then. I wish this one could talk, it has to tell quite a story.



(#30629169) the least "equipped" and plainest, is the "drafted" conversion of a 9-jewel grade 809, with "Correlator/Conel" balance and hairspring. Likely a Roth Brothers conversion, there are beefy extra jewels to make the 15, and only a seconds hand on the dial, yet as Tom McIntyre implied in "From War To Boudoir" the time keeping is on par with my Hammy 22, and both (currently) do better than the Kirov 6MX sitting next to them.



I guess, getting right down to it, I'd like more history and information on the Walthams because as good as the Hamilton 22 is when you've seen one, you've seen them all... unchanged except for a winder mod throughout its production. IMO, traditional Marine Chronometers are frankly arcane and the Hamilton 21 with its 472 production changes is just too highly rated and spendy.

Harrison's success came in the form of a large watch and to my mind Waltham's 8-day stems from the same logic and that logic culminated in the brilliant Hamilton 22. The Waltham just winds up being the most entertaining and affordable of them all.

I wish I could add some information to what you already know, but these are beyond my expertise. You do have a very nice "mini" collection though. One minor additional thought beyond what you have already said, military timepieces were regularly repaired over the years typically with little concern by the military personnel who did the repairing for "keeping everything original" as opposed to getting it back in service. So what you see now on these may or may not have been original to them. One additional very minor observation is that military timepieces often did not stay in one place in terms of being mounted in a specific ship or aircraft or whatever. They were swapped out so it is difficult to say much about which specific ship or aircraft or whatever they were originally installed in. When one is lucky to have some reliable provenance it can be a bit risky to assume that the particular timepiece was always with that original installation.