4 TIMBER AND SOME OF ITS DISEASES, [chap. 



which mark the ^' grain '' are continuations of the Hnes 

 which mark the annual rings, as shown in Fig. 2, 



Fig. 2. — Portion of segment of wood from a log such as Fig. i, supposed to be slightly 

 magnified, a, annual ring ; tn, medullary rays ; in', the same in vertical section; 

 fT, the boundary line between one annual ring and another; j;^, autumn wood; sp, 

 spring wood ;/, the pith. 



which represents on a larger scale a segment such as 

 could be cut from a log in the way described. It is 



