THE STEM 



121 



t rrr 



Fig. 138. — Diagram to show 

 the common method of sawing a 

 log. The circles represent rings 

 of annual growth : R, R, diam- 

 eter of the log ; r, r, r and t, t, I, 

 boards cut perpendicular to it, 

 givdng for the two or three cen- 

 tral ones radial, for the others, 

 tangential, cuts. The waste por- 

 tions are the " slabs " and "edg- 

 ings," shown in the dark seg- 

 ments at R, R, and the small 

 triangular blocks, e, c, e. 



radius of a log. Repeat the geo- ^ t rrr 



metrical principle upon which such 



a cut is described as " tangential." 



It passes through the medullary 



rays and the annual rings diagonally 



(Fig. 136), and is the cheapest way 



of cutting timber, "since the entire 



log is made into planks and there 



is no waste except the " slabs " and 



'' edgings," as shown in Fig. 138. 



The cut ends of the medullary rays 



appear on the surface as small lines 



or slits (Fig. 137), and give to this 



kind of plank its peculiar grain- 

 ing. The wavy or " watered " 



appearance of the annual rings 



(Figs. 133, 136, 140, 141), so often 



seen in cheap furniture and in the woodwork of cheaply 



constructed houses, is caused by the tangential cut, which 



strikes them at various angles. 



135. The radial, or quartered cut, 

 familiar to most of us in the " quar- 

 tered oak " of commerce, passes 

 through the center of the log and 

 cuts the rings of annual growth per- 

 pendicularly, giving it the "striped" 

 appearance (Fig. 135) seen in the 

 best woodwork. It gets its name 

 from the practice of dealers in first 

 sawing a log into quarters and then 

 cutting parallel to the radius pass- 

 ing through the middle of each 

 quarter, as shown in Fig. 139. In 

 this way each cut strikes the rings 

 perpendicularly, but except in the 

 case of very large logs, only narrow 



Fig. 139. — Diagram illustrat- 

 ing the "quartered " cut : d, d and 

 d' d', radial cuts (diameters) by 

 which the log is " quartered " ; 

 c, center of the log ; r, r, radii 

 passing through the middle of 

 each quarter, parallel to which 

 the planks f, t, t are cut. The 

 circles represent rings of annual 

 growth. 



