114 PROPERTIES OF WOOD. 



In broadleaved wood the softer and longer the fibres and 

 the looser the texture of the wood, the greater the difficulty 

 of sawing ; the section then becomes rough and much saw- 

 dust is produced, indicating difficulty in the work. Sa\\ 7 ing 

 is easier for dense short-fibred wood, and smooth cuts with 

 little sawdust result. It is therefore easier to saw hard 

 broadleaved wood than soft broadleaved wood. Coniferous 

 wood is the most easily sawn, on account of its simple 

 anatomical structure and fine medullary rays. 



Moisture diminishes the hardness of wood, but increases 

 the pliability of its fibres. In the case of hardwoods this 

 increase of pliability is not great, and for most conifers does 

 not appear to counterbalance the advantage of the softness 

 of the moist fibres. Hence, pine, larch and spruce woods 

 are more easily sawn green than dry ; but in the case of 

 certain soft-fibred, loosely textured woods, the pliability of 

 the fibres counterbalances the advantage of moisture, as for 

 instance in poplar, aspen, birch, willow, etc., the timber of 

 which is generally easier to saw dry than green. 



If we take the resistance to the saw across the fibres offered 

 by beechwood as 1, Gayer's own experiments in the case of 

 freshly felled wood give the following results : 



Resistance to saw. 



Scots pine, silver-fir, spruce . . . = 0*50 0*60 



Maple, larch, alder = 0'75 0'90 



Beech = TOO 



Oak = 1*03 



Sallow, aspen and birch . = 1*30 1*40 



Lime, willow and poplar . = 1*80 



With augurs and other tools used for boring wood, which 

 both split and cut, the work is easiest when commenced on a 

 tangential section of the wood and therefore the boring is 

 radial. Boring from a tangential section is more difficult, and 

 from a transverse section most difficult. Screws act like augurs. 



Nails are driven into wood most easily from the transverse 

 section, but then hold badly. It is difficult to drive nails into 

 wood that is coarse-grained, but as they then hold well and 

 the wood has no tendency to split, such wood, e.g., elm-wood, 

 is often preferred for packing-cases or boxes for tin-plates, etc. 



