I was cleaning up in an old barn today, and happened upon this device, the use I can’t even imagine. It’s about 3 1/4” long and opens symmetrically. There are small points in the “jaws” and then the adjustable arm with another point on it. Any ideas, anyone?
Update; see comment from reader "pzak" for the most likely identification. I will talk to a watchmaker contact to see how it might be used.
New update, Feb 27 2020.
The watchmaker calls them truing calipers. They are used to check and correct any wobble in the balance wheel. The wheel staff-ends are held between the points, the pointer arm is used as an indicator.
Better explanation here.
A different type of truing calipers, with sprung jaws.