gidly at any part of the circlel.y means of a shoe and thumb-nut. A spring on this clamping-arm holdsthe vernier-arm against the end of an adjusting-screw, working in a5j)lit-nut also on the clamping-arm. The nut has a clamping-screw toIr.ke up any wear and lost motion. By this arrangement, the arm… … Half Circle. 185 Improved Protractor, J^ Circle % Degrees, reiadingto i minute, 7-inch J20 00ISO Improved Protractor, )^ Circle ^ Degrees, reading to I minute, 8-inch 22 00187 Improved Protractor, j^ Circle)^ Degrees, reading to I minute,io-inch 25 00 Whole Circle. 190 Improved Protractor, Whole…