16 



TIMBER. 



thus fully accounting for the difference in weight and firmness of the 

 wood of these different parts. In the longleaf pine the summer wood 

 often forms scarcely 10 per cent of the wood in the central 5 rings; 40 

 to 50 per cent of the next 100 rings; about 30 per cent in the next 50, 

 and only about 20 per cent in the 50 rings next to the bark. It averages 

 45 per cent of the wood of the stump and only 24 per cent of that of 

 the top. 



Sawing the log into boards, the yearly rings are represented on the 

 board faces of the middle board (radial sections) by narrow, parallel 

 stripes (see fig. 3), an inner, lighter stripe, and its outer, darker neighbor 

 always corresponding to one annual ring. 



On the faces of the boards nearest the slab (tangential or " bastard" 

 boards) the several years' growth should also appear as parallel, but 



much broader stripes. This they do 

 only if the log is short and very perfect. 

 Usually a variety of pleasing patterns 

 is displayed on the boards, depending 

 on the position of the saw 

 cut, and on the regularity 

 of growth of the log. (See 

 fig. 3.) 



Where the cut passes 

 through a prominence (bump 

 or crook) of the log, irregu- 

 lar, concentric circlets and 

 ovals are produced, and on 

 almost all tangent boards, 

 arrow, or V-shaped forms 

 occur. 



ANATOMICAL STRUCTURE. 



Fig. 4.— Wood of spruce. 1, natural size; 2, small partof 

 one ring magnified 100 times. The vertical tubes are 

 wood fibers, in this case all "tracheids." m, medullary 

 or pith ray; n, transverse tracheids of pith ray; a, b, 

 and c, bordered pits of the tracheids, more enlarged. 



Holding a well- smoothed 

 disk, or cross section one- 

 eighth inch thick toward the 

 light, it is readily seen that 

 pine wood is a very porous structure. If viewed with a strong magni- 

 fier, the little tabes, especially in the spring wood of the rings, are easily 

 distinguished and their arrangement in regular straight radial rows is 

 apparent. Scattered through the summer wood portion of the rings, 

 numerous irregular grayish dots (the resin ducts) disturb the uniform- 

 ity and regularity of the structure. Magnified 100 times, a piece of 

 spruce, which is similar to pine, presents a picture like that shown in 

 fig. 4. Only short pieces of the tubes or cells of which the wood is 

 composed are represented in the picture. 



The total length of these fibers is one-twentieth to one-fifth inch, 

 being smallest near the pith, and is 50 to 100 times as great as their 



