120 A B C OF THE STEEL SQUARE 



This indicates the center of the rail. Run lines 

 radial from A as shown ; these are the riser lines. 

 Draw the lines B C and C D, which are the 

 tangents. Draw the diagonal B D. To make 

 the bed blocks, procure a piece of one inch stuff-: 

 take it to the width shown at B C ; square on a 



mark about 3 inches from the end (this is to 

 allow for the shank to clear the saw table ; the 

 block is shown at Fig. 83 without the 3-inch 

 allowance). Take on the steel square the rise on 

 tongue and going on blade of the straight flight 

 of stairs; mark on the inch board at tongue; 

 this is pitch of the first tangent. Take the 

 height at D, which is one and a half risers 



