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> *From: *Noell Wilson
> *Date: *2024 Jan 26, 07:33 -0800
>
> "The very few ship’s chronometers that I have seen are
> simply high-grade pocket watch movements in a gimbal mounting and the
> whole thing in a nice box.  They are typically rated for positions and
> temperature.  Also, with non-magnetic hairsprings.  The temperature
> compensation is accomplished due to bi-metallic rim of balance wheel
> which is cut at (2) opposed locations.  A railroad grade pocket watch
> movement has the same construction."
>
> The above is from someone who repairs mechanical watches and clocks and
> is willing to open up an Omega watch. His opinion seems to slightly
> short-change choronometers but I don't know enough to judge.

I thought marine chronometers had a special escapement (not found even
on railroad grade pocket watches) to keep the balance wheel as free as
possible. Also, there was a mechanism to maintain constant force as the
mainspring ran down. And perhaps a helical (not spiral) balance spring?
This nautical magazine article from the 1850s doesn't clear up those
points, but it's interesting nevertheless.

"Chronometers For Her Majesty's Ships"

https://archive.org/details/the-nautical-magazine-and-naval-chronicl-1858/page/349/mode/2up?view=theater

--
Paul Hirose
sofajpl.com

   

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