INTRODUCTION. 



will suppose that he chances to select as a sample some 

 particular piece of wood. 



In the first place, or at any rate after satisfying 

 himself as to the species of timber concerned, he will 

 examine the cut ends — the transverse section — and see 

 what marks are there visible. He will probably make 

 sure that the annual rings are of the right average 

 breadth, and evenly grown without interruption : these 

 matters are of some importance, and there are differences 

 in detail required for each kind of timber. 



He will at the same time assure himself as to the 

 soundness or otherwise of the central parts, round the 

 pith ; for in old trees the inner portions of the heart- 

 wood (the oldest of all) are apt to decay, and if this 

 •decay has commenced the timber-merchant must take 

 steps to find out how far the useless portions extend 

 into the log, and of what nature the decay is, because 

 some forms of rotting are much more damaging and far- 

 reaching than others. 



He will also be on the look-out for various indica- 

 tions of damage only known to those who are in the 

 habit of examining large timber. Certain fissures, or 

 cracks, are very common in felled timber ; and while 

 some of these only extend slightly into the log, others, 

 again, are indicative of serious defects which will cause 

 great waste when the logs are sawn. 



These fissures are mostly apparent at the cross 

 section, especially of the lower parts of the log. Some 

 of them exist before the tree is felled, but others only 

 appear afterwards. Certain of these fissures occur in 

 the direction of the radiating lines known as medullary 

 rays, the wider part of the fissure being next the pith, 

 while it narrows more and more as it extends outwards. 

 If these " Heart-sfiakes" as they are called, exist to any 



B 2 



