Forest Service, U. S. Dept. of Agriculture Mechanical Pulp. PLATE III. 



FIG. 1. THREE TO THE INCH SOLID; STRAIGHT-CUT BURR. (HEMLOCK RUN No. 46.) 



FIG. 2. THREE TO THE INCH SOLID; STRAIGHT-CUT BURR. CUT OVER WITH TWELVE 

 TO THE INCH SOLID; SPIRAL BURR. (HEMLOCK RUN NO. 51.) 



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FIG. 3. Six TO THE INCH DIAMOND POINT BURR. (JACK PINE RUN No. 17-1.) 



