86 A B C OF THE STEEL SQUARE 



back from 17 one-half the thickness of the rafter., 

 and this will be the gauge line point from which 

 to remove the wood back to the center line of 

 hip, and the measurement from the edge of the 

 rafter taken vertically down to the gauge point 

 set off on the plumb cut regulates how far apart 

 the parallel lines of the seat cuts will be under 

 the above conditions. This rule applies to any 

 roof so long as the pitches are regular. 



Fig. 55. 



Proceed in like manner for the octagon hip, 

 the variation, however, is practically one-half of 

 the above results for the square eornererl 

 building. 



Fig. 55 illustrates side cut of the jack, 12 on 

 the tongue, and 15 (length of the common 

 rafter) on the blade. 



