THE STEM 



121 



radius of a log. Repeat the geo- 

 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 



rrr 



* trrr 



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, t, 

 boards cut perpendicular to it, 

 giving 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, e, e. 



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 



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 plants t, t, t BIG cut, The perpendicularly, but except in the 



circles represent rings of annual 

 growth. 



case of very large logs, only narrow 



