STRUCTURE OF STEMS; WOOD 



293 



cut in this way. Boards made by sawing through the pith rays are 

 better than slash-sawed boards, because they warp less, and have a 

 more even grain. Quarter sawing is radial sawing. The log is first 



FIG. 240. A Log Boom. Courtesy of the Field Museum. 



cut lengthwise into quarters, and boards are cut from the quarters as 

 nearly through the pith rays as is possible. The pith rays are the 

 "silver flakes" that give to quarter-sawed oak its beautiful marking. 



FIG. 240a. A Lengthwise Section through the Pith Rays, Showing the Ends of Quarter- 

 Sawed Boards. 



Knots in boards are the remains of branches which grew on the 

 trunk when the tree was young. In old trees, these remains have 

 been entirely covered up by the annual rings. 



