124 



ABC OF THE STEEL SQUARE 



Now run parallel lines off the tangent B for 

 the shank ; this completes the face mold, which 

 is now ready for the face of the plank. Wreaths 

 for stairs with flights which stand at either 

 acute or obtuse angles to each other may be set 

 out by the methods that have been here de- 

 scribed. The only difference, practically, is that 

 the bed block is made acute or obtuse to suit 



?ig. 85. 



plan of tangents. The device shown at Fig. 85 

 has been found to answer excellently for strik- 

 ing out ellipses. To make this, procure two 

 screws %. inches long, also a piece of brass tube 

 that will just slip on the plain part of the 

 screw without shaking. Counter sink out the 

 ends until the screw heads are flush ; cut two 

 pieces off the tube three-sixteenths and file up 

 true these pieces are best held by sinking 

 them with a bit in a piece of hardwood. Now 

 when about to strike an ellipse, drive these 

 screws in with the collars on to half major and 



