78 



TECHNICAL I'KOPEHTIES OF WuOD. 



of coniferous wood, a strong' scent of turpentine is observed. 

 Several other species have scents peculiar to themselves, but 

 which cannot be described. Whenever the scent is unpleasant 

 and mouldy, it is a proof of more or less advanced decay. 



The colour of fresh sections of wood oft'ers an excellent test 

 of its soundness. Uniformity of colour, and for most species 

 the lighter tints, are usually signs of sound- 

 ness. Patches or stripes of darker colour 

 in a wood prove the opposite. In the case 

 of spruce and silver-fir even a very slight 

 brownness of the wood is a bad sign, and 

 such wood should be unquestionably rejected 

 for use as timber. In the case of oak-wood, 

 bright or brownish yellow colour is a healthy 

 sign, and even a rosy colour would not 

 prevent its use as timber, but brownish or 

 cinnamon-red and dark brown colouration are 

 highly suspicious. Green colour is a sign of 

 complete decay. Dark blue colour of coni- 

 ferous wood felled during the growing season 

 and not barked, points to a commencement 

 of decay in the cambium and sapwood. 



Striking the reverse of an axe against a 

 stem at different places, from the clear or 

 dull sound given out, leads to conclusions 

 as to the soundness of the tree. At the same 

 time the practice of one man striking at one 

 end of a log and another placing his ear at 

 '^if ^^1 the other end affords no certain test of souud- 



l^^'jB ness. The best way to test an occluded knot 



in a tree is to remove the now wood over 

 the wound, and probe the latter with a knife 

 or other tool. 

 In the case of standing trees, the detection of unsoundness 

 is naturally more difficult than for logs, but the condition of 

 the crown and branches may give useful indications in this 

 respect : — whether for instance the tree is stag-headed, or has 

 any large dead boughs or snags, whether during the growing 

 season the foliage is complete, or partly dead. 



