520 



BELL SYSTEM TECHNICAL JOURNAL 



Employment of the new standard ultimate fiber stresses of wood 

 poles is provided for under rule 261-4-c of the National Safety Code. 

 With the revisions necessitated by their adoption, Table 20 of the 

 Code will appear as indicated in Table 3. 



w.u. 



A.T.8.T. 

 A.S.A. 



N.E.L.A. 

 W.U. [_ AA 



A.T. X,T. 

 A.S.A. 



(AAA I AA |A 



B I C 



t I I H 



_ 



rz 



JAAA 



N.E.L.A. 

 W.U. 

 A.T.&T. 

 A.S.A. 



N.E.L.A. 

 W.U. 

 A.T.&T. 

 A.S.A. 



N.E.L.A. 

 W.U. {^ 



A.T.&T. 

 A.S.A. 



AA I A 



N.E.L.A. 

 W.U. 

 A.T.iT. 

 A.S.A. 



AA| A 



i AAA I AA 



m 



JAAA |AA 



2 I 3 



A B 



(aaaIaa 



•TT 



B 



1{aaa|aa 



C I D 



. C 

 A I B 



C I D 



Cl D l> I 



111 



XJ 



XI 



I 



HEIGHT 



IN FEET 



25 



30 



35 



. C I D 

 A I B I C' 



I 6 I H 



H 



in 



45 



50 



40 



56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 



MINIMUM CIRCUMFERENCE AT 6 FEET FROM BUTT IN INCHES 



Pig 1 — Representative block from the graphical charts for southern yellow pine- 

 current dimensions compared with the new standard tables. 



The material requirements of the several specifications cover shape, 

 and straightness of grain, and limit or prohibit such defects as knots, 

 checks, insect damage and decay. Without detailed reference to what 

 might be called the appearance requirements, it may be said that the 



