A B C OF THE STEEL SQUARE 125 



minor, measured from the point of the trammel 

 to the inside of the collar for the major, and 

 to the outside of the collar for the 'minor. It 

 will be found that if the collar has been made 

 true, the trammel will slip around the curve 

 without causing the square to slip about, the 

 collars acting as rollers. 



W. T. Jones, Boise City, Idaho, would like 

 to know of a ready way to frame hip roofs and 

 roofs of irregular or different pitches with the 

 steel square, including lengths and bevels of 

 all rafters. 



Answer: These problems along with many 

 others are discussed and explained at length in 

 my larger works on the Steel Square, but the 

 following, which is somewhat condensed, does to 

 some extent cover Mr. Jones' inquiries: 



Suppose A, B, C, D, Fig. 86, to represent one 

 end of a hip roof with a span of 24 feet and a 

 1 0-foot rise. The side rafter I D shown in top 

 sketch will have a run of 12 feet. The common 

 rafter at the end of building, I L, has a run of 

 1 6 feet, with the same rise, so that the ends and 

 sides of the roofs have different pitches. The 

 lengths and cuts of the common rafters are ob- 

 tained as shown in Fig. 87, by taking 12 on the 



