Posted 4 years ago
Hand held tach. Made by L.S. Starrett. Patent dates are Apr 13 1897 and Mar 28 1905. It works by holding a triangular pointed end (left side in pic.) to the center of a rotating object. Then time for 1 minute and add up the nembers on the dials. Gives you RPM. I've had it for about 7 or 8 years sitting on a shelf above my desk collecting dust. Got it from a friend.