A bit of a mystery? Cast iron trumpet...

[Wetcoaster]

I recently bought this diaphone, not even knowing what a diaphone was at that point. Reportedly this came off a vessel that was built in the early 1920s, probably here in the Pacific Northwest, and probably in Vancouver, B.C. I guess that might be relevant if this is a Canadian-made diaphone? There is no maker's plate and no sign of holes for one. On top of what I'll call the "generator" (until I get the terminology right!) there is a stamped three digit number as shown in the photos. The horn had some pretty heavy rust scale inside so the marine story fits from that angle. The only similar trumpets I have seen are on much larger Type F Diaphones. The trumpet is 43 inches long and about 13.5 inches in diameter at the mouth and weighs about 80 pounds I'd say. The piston diameter is 2 & 1/8" and overall length of the piston is 2 & 15/16".

The piston is a very close fit so I'm guessing either this one didn't get much use or it was very well lubricated when it was in use.

I have begun to restore it, and would appreciate any input on what this horn is exactly, how old and where it was made. Input on restoration dos and don'ts would also be helpful. Thanks in advance!

[Wetcoaster]

A few more photos.

[Jim]

You know what the Keno brothers would tell you, don't you?
Clean it, heck maybe even touch it, and there goes its value.
If you decide to anyway, I would say you have a big job.