44 



A B C OF THE STEEL SQUARE 



In Fig. 21 there is shown a quarter circle, XG, 

 described from the center C. Along the horizon- 

 tal line, AB, the blade of the square is laid with 

 12 of the blade against the center C, from 

 which the quadrant was struck. Now if we dir 

 vide this quadrant into halves, thus establishing 

 the point E, and if from E we draw a line to 

 the center C, which is 12 of the blade, it will be 



Fig. 21. 



found that it cuts also 12 of the tongue. If we 

 complete the figure by erecting a perpendicular 

 line from the point X, and intersecting it with 

 a horizontal line from G, thus establishing the 

 point O, it becomes very evident that CE is the 

 miter line of a square. 



If we bisect XE, thus establishing the point 



