A B C OF THE STEEL SQUARE 35 



in order to give the tool necessary stability, 

 and, therefore, as the embodiment of a right 

 angle it is of a form to give us both the exterior 

 and interior shape. The blade of the square is 

 made a little wider than the tongue, more for 

 convenience, I think, than for any other reason, 

 for I have seen squares somewhat old, to be 

 sure, and made long before the tools which are 

 now in most common use were sent out from 

 the factory, of which the blade and tongue were 

 approximately of the same width. 



The blade of the square, as commonly con- 

 structed, is 2 feet, or 24 inches long, and the 

 tongue somewhat less. I have seen squares of 

 which the tongue and blade were of equal 

 lengths, and also those, the blade of which were 

 considerably longer than those of the square of 

 present make, and still others of which the 

 tongues were considerably shorter than is now 

 the rule. But this is long ago. The most com- 

 monly accepted dimensions for a carpenter's 

 square at the present time are, blade 24 inches 

 long, tongue 18 inches long, blade 2 inches wide 

 and tongue 1% inches wide. This gives for 

 inside measurements blade, 22% inches and 

 tongue 16 inches. 



I have described the square as the embodi- 

 ment of a right angle. If the square is not a 



