U.S. Frankford Arsenal Caliper 1869

That is a fantastic tool. I'm jealous!![]()
If I remember correctly, I found this at a garage sale where you would gather any stuff you wanted, go up to the cashier and they would give you one price for the lot.
That day we had a bunch of cool stuff and after dividing the amount of things we had into the cashiers single lot price, the caliper cost me $.25 cents.
It was originally rusted and stuck fast. This is how it turned out after soaking in vinegar or Evapo-Rust. I can't remember which.