I picked up two small lathe chucks last weekend at an auction sale, one is a 3" 3 jaw chuck stamped A F CUSHMAN MAKER ...... HARTFORD CONN ...... Pat Nov 14 1871. The second is a 3-1/2" chuck has 4 jaws, the chuck jaws are not completely independent as they work in pairs, the jaws are about 1/4" in height, the back side mounting is a 1/2" diameter socket with a set screw. Pictures are below, can anyone tell me what the second chuck would have been used for? Thanks paulygman.