Douglas Fir Fiber 



691 



ground. Inspection of the location of the average longest fiber 

 in the different rings, as shown by in Figure 1, shows quite posi- 

 tively that the longer fiber in the annual ring tends to be near the 

 ground in the rings first formed but to be farther from the pith 

 and higher from the ground in rings formed later. This agrees 

 with Bailey's modification of Sanio's law, i. e., that the longer 

 tracheid length occurs higher from the ground in the rings nearer 

 the bark. 



A comparison of the length of fiber with strength values seems 

 to indicate no relation except that both these factors tend to 

 increase rapidly up to a certain distance from the pith and then 

 vary irregularly within comparatively narrow limits toward the 

 periphery, both tending to increase slightly. However, the fact 

 that the butt gives in general the highest and the top the lowest 

 strength values rather indicates that the fiber length is not cor- 

 related with strength, since the fiber length is low in both these 

 regions. It, therefore, appears that no marked relation exists be- 

 tween strength and fiber length in the vertical direction, although 

 there may be a relation in the horizontal direction.* 



Table V — Average length of fiber in discs from trees 2-5 and 2-1 from Coast and 

 3-8 and 3-10 from Mountain Region of British Columbia. 



* For complete discussion of strength values of Ship. 2, tree 1, see "The 

 Mechanical and Physical Properties of Canadian Douglas Fir." R. W. 

 Sterns, Dominion Forestry Branch Bulletin No. 59. 



* In choosing annual rings the last was taken and then every twentieth, 

 going toward the pith. Since the exact number of annual rings was not 

 170, the number of annual rings between the pith and the next ring removed 

 was variable being 8 for 2-5. 8 for 2-1, 20 for 3-8 and 9 for 3-10. See Figure 1 

 or method followed. 



