76 ABC OF THE STEEL SQUARE 



building by the decimal .56, 24<X -56=13.44, or 

 as near as can be worked by the square, 13 feet, 

 5 inches. 



Let us try the same rule for a greater width 

 say 60 feet. By finding the hypothenuse we find 

 as near as can be used by the square, 33 feet, 

 6% inches. By my method it would be 60X-56, 

 or 33.60, equal to 33 feet, 7 inches full. By this 

 method the rafters in wide buildings are a little 

 long. Thus, if the building is 52 feet wide, by 

 the hypothenuse it would be 29 feet, 1 inch ; my 

 way it would be 29 feet, 1% inches. I consider 

 this an advantage, as it leaves the point of the 

 rafter very slightly open. 



For one-third I follow the same plan, only 

 using the decimal .6. Unlike the decimal used 

 for a quarter pitch the lengths are a very small 

 fraction short; as, for instance, a rafter for a 

 building 60 feet wide, by finding the hypothe- 

 nuse, would be 36 feet, 1-16 of an inch. By my 

 way, 60X- 6=36 feet. A slight difference, 

 truly. If building is 48 feet wide, then by 

 the first method we find 28 feet, 10 inches full ; 

 by my way, 28 feet, 9% inches. A little prac- 

 tice will enable the mechanic to allow just enough 

 to make up for the slight difference, so that 

 when rafters are put together the fit will b* 

 perfect. 



