10 



BULLETIN 497, U. S. DEPARTMENT OF AGRICULTURE. 



Table 11. — Average strength values f<>r green and air-seasoned western yellow 

 pine in structural sizes and small pieces without defects. 



GREEN MATERIAL. 





Bending. 



Compression parallel to 

 grain. 



Compression perpendicu- 

 lar to grain. 















E 



o 



u 



ft 









63 H 









"3d 













— 



© 











s.y 









a a 





t/J 



a 





o 





Id 



.2 -■ 



jffl 



a 



5J 



to 





«C3 



■d 3 

 US 

 a i- 



a 



© 



CO 





X © 



al 



© — 







cj 



a 





5^3 









£ 



<u 





© © 



1 



CD 





a) © 















c 3 



c 3 



o 















t- ft 





I* 



o 



C 

 ft 



H 



a 







<2« 



ft 



o 



H 



ex 53 



a° 



© 



O 



© 



£ E 

 ft— 

 E.3 



o 



o 

 t-i 



s 



a 



CjO 



.a 



°o 



to 



'o 





3 



■a 



o 



.S 



3 



O 



o 

 a> 



t/5 



s 



3 



'3 

 3 



is 



3 3 



o 

 w 



s 



3 



'c 









P<r 









7,000 







Per 









Per 





Inches. 







cent. 



Lbs. 



Z&s. 



Z&s. 



Z6s. 



J?icftes. 





cent. 



£&«. 



Inches. 





cent. 



Z&s. 



5x8 



26 



15.6 



39.3 



26.7 



2,769 



4,560 



1,243 



4 x 4 x 16 



25 



43.2 



2,830 



5 x 8 x 20 



25 



42.9 



299 



2x10 



46 

 143 



17.3 

 15.9 



35.8 

 34.4 



26.4 

 26.4 



2,830 

 3,394 



4,272 

 5,659 



1,266 

 1,159 



















2x2 



2x2x8 



143 



37.6 



2,770 





















AIR-SEASONED MATERIAI 



5x8 



2x10 

 2x2 



15.2 



16. 



15.5 



12.6 

 13.2 

 11.6 



27.2 

 28.5 

 27.1 



3,976 

 4,502 

 6,660 



6,119 

 6,640 

 10,871 



1,521 

 1,595 

 1,534 



5 x 5 x 24 



12.5 5,758 



11.2 6,45^ 



13.0 



701 



RATIO— AIR-SEASONED TO GREEN. 



5x8- 











144 



159 

 196 



134 



156 

 192 



122 



126 

 132 



[4x4x16 1 





204 



5 x 8 x 20 







234 



2x10 











|5x5x24'J 













2x2 











2x2x8 





233 































The results of tests on green car sills (Table 1) show the weaken- 

 ing effect of knots to be directly proportional to their size and quan- 

 tity, the lower grades of timber having larger knots and a greater 

 number of them. Table 2, in which the air-seasoned sills are given, 

 shows a greater increase in strength through air seasoning in the 

 lower grades than in the clear sills. 



The material tested contained no shakes. The checking in air 

 seasoning was practically the same as that which usually occurs in 

 Douglas fir, western hemlock, and western larch. 



Failure because of spiral grain was quite frequent in the green 

 joists. This grain is very difficult to detect, the surface grain often 

 appearing straight and the resin ducts indistinct. Plate II is an 

 excellent illustration of this. 



Both the joists and the car sills contained an unusual amount of 

 sap wood, but this in no way altered the strength of the material 

 under consideration. However, because of its lack of durability, 

 sapwood is undesirable in timbers used under conditions favorable to 

 decay. 



