18 ABC OF THE STEEL SQUARE 



all cases. Always remember that the cut comes 

 on the tongue, or last named figure. It is so 

 arranged in all cases. 1 



Octagon, "Eight-square" Scale. This scale 

 is along the middle of the face of the tongue, 

 and is used for laying off lines to cut an "eight 

 square" or octagon stick of timber from a 

 square. 



Suppose the figures A, B, C, D, Fig. 2, is the 

 butt of a square stick of timber 6x6 inches. 

 Through the center draw the lines AB and CD 

 parallel with the sides and at right angles to 

 each other. 



With the dividers take as many spaces (6) 

 from the scale as there are inches in the width 

 of the stick, and lay off this space on either side 

 of the point A as Aa and Ab ; lay off in the same 

 way the space from the point B as Bd and Be; 

 also Cf and Cg and Db and De. Then draw the 

 lines ab, cd, ef and gh. Cut off the solid angle 

 E, also F, G and H ; there is left an octagon, or 

 "eight square" stick. This is nearly exact. 



Brace Measure. This is along the center of 

 the back of the "tongue," and gives the length of 

 the common brace. 



18-18 25.45 in the scale means that if the run 

 is 18 inches on the post and the same on the 

 beam, then the brace will be 25 45-100 inches. 



