FOREST UTILIZATION 59 



tonwoods), however, moist wood is tougher and 

 therefore harder as well, 

 (d) Frost increases the hardness. 



SCHEDULE OF HARDNESS. 



Hard. Medium. Soft. Very soft. 



Hickory Ash Chestnut White pine 



Dogwood Oak Tulip tree Sugar pine 



Sugar maple Elm Sweet gum Sequoia 



Sycamore Beech Douglas fir Paulownla 



Locust Cherry Fir Willow 



Hornbeam Mulberry Yellow pine 



Persimmon Birch Larch 



Sour gum Linden 



Lougleaf pine Horse chestnut 



Hemlock 

 Cottonwoods 

 Spruce 



III. Cleavability or fissibility. 



Cleavability is the resistance of fibre to axe, saw and wedge, 

 worked lengthwise in the direction of the fibre. Radial 

 cleavage is usually by 50 % to 100 % easier than tangential 

 cleavage (except in black gum). 

 Factors of Cleavability are : 



(a) A straight, long, elastic fibre. 



(b) Heavy and high medullary rays. 



(c) Straightness of growth. 



(d) Branchiness. 



(e) Moisture (very green and very dry wood splits 

 ^ best). 



(1) Frost (reduces the cleavability). 

 (g) Hardness and softness (extremely hard and ex- 

 tremely soft wood splits badly. This rule holds 

 good only in hardwoods). 



SCHEDULE OF CLEAVABILITY. 



Hard to split. Medium to split. Easy to split. 



Black gum Oak Chestnut 



Elm Ash Pines 



Sycamore Larch Spruce 



Dogwood Cottonwood Fir 



Beech Linden Cedar 



Holly Yellow poplar . . 



Maple Hickory 

 Birch 

 Hornbeam 



IV. Pliability. 



Under pliability we combine flexibility and elasticity. 



(a) Flexibility; wood which is easily bent without 

 breaking is flexile (flexible). Softwoods are nat- 

 urally less flexile than hardwoods. 

 Flexibility depends on : 



1. Toughness and cohesive force of fibre. 



2. Moisture, which increases it very much. 



3. Heat, which increases it. 



4. Age of tree, inasmuch as young shoots 



are tougher than old wood. 



5. Impregnation, natural as well as artificial, 



