PROPERTIES OF WOOD AND THEIR USES 59 
and more durable and possess greater fuel value. The 
lighter woods are inclined to season readily and to 
work easily, but usually lack strength and durability. 
Strength. A wood is said to be strong when it re- 
sists pressure or tension from various sources; the 
pressure may be applied either with or across the grain 
and different species show a varying power of resistance. 
Both longleaf pine and white oak resist pressure with 
the grain éspecially well and hence they can be used 
to advantage as columns where great weight must be 
supported. Other species show varying resistance to 
different kinds of strains and the Forest Service Timber 
Testing Laboratory at Madison, Wisconsin, has made 
many experiments on all kinds of woods to find out the 
uses to which they are best suited. 
Within the same species, the strength of wood is due 
to condition, its freedom from knots and cracks and 
also to the amount of water it contains. Freshly cut 
timber is weak in comparison with the same stick when 
thoroughly seasoned. The weight of wood is generally 
a good measure of its strength, as woods that are heavy 
when dry contain a large amount of wood fiber and 
consequently break or crush with difficulty. 
Other properties such as toughness, cleavability, 
elasticity, etc., might be mentioned. Hickory is es- 
pecially valuable for use In wagon making on account 
of its hardness and toughness and from the elastic white 
ash are made much of athletic equipment so dear to 
the heart of the outdoor boy or man. Baseball bats 
and snowshoes are made from ash, as it combines tough- 
ness and elasticity to a marked degree. 
Defects ——Wood, however, is rarely perfect and may 
contain defects which will seriously impair its strength 
or prevent its use for a given purpose. Knots are per- 
