Nickel (?) Hermagis Petzval....

[Sevo]

None of the Adams process nickel Colt 1870s-1880s revolvers I've seen are dull! Nor the nickle plating on old potbelly stoves, steam guages, etc. The 1870s Nickle was very shiny, based on how much the underlying steel or base metal was polished.

No - that is the other way around. Pre WWI nickel platings can be glossy, but they were deposited dull and had to be polished (and to be thick enough that the polishing did not wear them through), almost regardless of the surface below. Later processes could create platings more shiny than the substrate they are on, so they were generally made on a polished base, as the final step.

Given that this lens seems to be glossy down to the engraved lettering (and moreover precedes the time when nickel plating lens size objects became feasible), it can't have been plated at the time of its making - if that should, against all intuition, really be the original finish, it must be solid Nickel (or some type of German Silver). Far more likely is that it was plated long after its production, anywhere within the last 100 years.

[goamules]

Good forensic analysis, professor! I never thought of looking at the engraving plating. I agree, as I said in my first post; never seen a nickel Hermagis Petzval, and it was done later.

[Steven Tribe]

Back to the lens, proper Emil!

Have you discovered how to unscrew the main barrel into 2 parts?