This is a nice, 4" outside spring caliper made by a rarely seen maker, it is marked "Sawyer" on the steel beam.   Sawyer Tool Company was located in Fitchburg Mass..  It measures 4.75" long overall and has a very nice snug pivot joint, and strong spring. The threaded fine adjustment works great, good threads. It features nice flatten legs, and rounded end tips. A nice looking tool from the pre-1915 era, perhaps a bit earlier.  No rust, some minor pitting, no damage, minor wear overall, in working order.