112 



THE SCALING OF DEFECTIVE LOGS 



Seams, Heart Checks, Frost Cracks or Pitch Sea7ns. Seams are cracks 

 penetrating the log from the surface. They have the same effect as 

 shake, in causing boards to fall apart, and the deduction is made by 

 enclosing the seam in a timber of required dimensions to remove it. 

 Twisted grain, causing seams to take a 

 spiral form, results in ruining either the 

 entire log or a large per cent of its volume. 

 The deduction must include the entire 

 seam in a squared timber. The width of 

 the plank deducted should not include the 

 portion which would be slabbed in sawing. 

 Method of deducting for a twisted seam 

 or check: The wedge enclosing the seam is 

 scaled as a per cent of total scale of cylinder 

 proportional to areas of cross sections. 

 Fig. 17.— Method of deduction g^^ ^^ ^^^^ jogg^ of i^^ger diameters, the 

 for a seam, or a heart check. ,. , , • tt^- 10 • + 



, , , entire segment shown m b ig. 18 is not 



lost, if short boards of scaling length can 

 be sawed from the butt and top portions 

 of the segment respectively. This saving 



will not amount to more than one-third of the total deduction. 



Worm Holes. If the size and extent of worm holes is not sufficient to 



cull the boards, their presence will not cause a loss in scaling. It is 



difficult to judge the extent of damage from worm holes, except by local 



experience in observing the sawing of logs. 



The width of plank 

 exchide both the taper of log 

 and the slab, on the small end. 



Fig. 18. 



-Position of twisted seam at butt, and at top of same log, and resultant 

 sector deducted in scaUng. 



Rot Entering from Knots. The most common forms of rot enter 

 the tree through dead limbs, stubs or knots, or through wounds or abra- 

 sions, which by penetrating or interrupting the layer of bark and live 

 sapwood, expose the heartwood to infection. From these points of 

 infection the fungus spreads through the heartwood both upwards and 



