Comment by K0balt

Interesting, maybe new for pocket compasses. I had a marine plotting compass that used a massive copper cylindrical housing, with a sapphire glass bottom and window. It was very well damped. It was made in the 1940s, presumably when yachts were mostly wooden. (More modern boats would usually need significant compensation) or maybe it wasn’t for marine use? But anyway, it was a great plotting compass that I used extensively on my little fiberglass weekender sloop. Better than the westmarine garbage mounted on the cabin bulkhead by a long shot.