First of all, this is a very old saw and also, I think, an uncommon one. Which is not bad, but you might want to put this one up for awhile, and look for a different user.
The EAIA's Directory of American Tool Manufacturers shows this company in business in 1870. Apparently there is not much known of the company or a starting date and ending date would be given. In my mind this date is probably close. According to Phil Baker(he has forgotten more about backsaws than most of us will ever know) saw manufacturers quit using split nuts around 1867-1869 so the 1870 date is probably correct.
The fact that it looks like a "belt sander" was used, is pretty common on split nuts since the bolt and nut were both installed proud of the surface and then sanded flush with the wood. The wood also got a good sanding too.
If you haven’t ever tried to remove split nuts you might want to rethink doing it. After all this time they will not give up easily. You’ll probably wind up with the bolt shaft breaking. Normally these things are made of cast brass rather than being turned from bar stock so they aren’t real strong.
What kind of shape is the "etch" in? Does it say anything else besides Barber & Genn? Are there any pictures or shapes?
Mike
