ABC OF THE STEEL SQUARE 



83 



New suppose we want to find the lengths and 

 cuts *f the rafters for the % pitch. We take 

 9 01 the blade. Why ? Because the run being 

 12 itxihes, the span must be two times 12, which 

 equals 24, and since the pitch is reckoned by the 



Fig. 53. 



span, we find that % of 24 is 9, which represents 

 the rise of the foot run. Then 12 and 9 give 

 the seat and plumb cuts for the common rafter, 

 13 and 9 for the octagon hip or valley, and 17 

 and 9 gives the same for the common hip or 

 valley. In Fig. 53 I show each separately. 



