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BELL SYSTEM TECHNICAL JOURNAL 



* Section Sizes: 



Minimum = Sys" x 4^" 



End. Min. = 3ys" x 4" (viz. minimum at end of arm) 



Nominal = 31" x 4-^" 



"Table 4. — Section Modulus of Rectangular Section without Bolt Holes 

 {Calculation 8) 



Roofed Sections Between Pinholes 



As indicated in Table 1, three tabular calculations were made for roofed 

 sections between pinholes. In Calculations 1, 2 and 3 it was assumed that 

 the knots present were located (1) at the top, (2) at the bottom, and (3) 

 immediately below the top segment of the section, respectively. The re- 



sults relating to the 3^" 

 respectively, in Fig. 3. 



X 4^'' section are plotted as Curves 1, 2 and 3, 



