machine

This was found buried in a field in Washington County Pennsylvania about 3 inches or so down. Very rusted. Looks like iron maybe. What do you guys think it is? Thank you in advance!

This is a heavy steel ring about 18” diameter. The inner and outer rings are marked from 0 to 499. There are two small indicators that can slide along the inner and outer rings. The two heavier tabs do not move. There seems to be a race or groove between the two rings along which something...