A B C OF THE STEEL SQUARE 



51 



rafter. This will be ex- 

 plained at greater length in 

 the following pages. 



At Fig. 27 I show a 

 method of laying out a 

 rafter without making use 

 of a fence. In this case the 

 roof is supposed to be half- 

 pitch, so we take 12 and 12 

 on the square and apply it 

 to the rafter as many times 

 as there are feet in half the 

 width of the building, which 

 in this case will be 15 

 feet, as we suppose the 

 building to be 30 feet wide. 

 As the lower end of the 

 rafter is notched to sit on 

 the plate we must gauge off 

 a backing line, as shown, to 

 run into the angle of the 

 notch. This line will be the 

 line on which the gauge 

 points 12 and 12 on the 

 square must start from each 

 time. 



Starting from this notch 

 apply the square, keeping 



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