FIG. 207. PARALLEL RULER, METAL, FIELD'S ROLLING. 



FIG. 208. PARALLEL RULER, METAL, FIELD'S PATTERN. 



FIG. 209. PARALLEL RULER, FIELD'S PATTERN. 



FIG. 210. PARALLEL RULER. 



FIG. 211. XY. ROLLING (FIELD'S) PARALLEL RULE. 



