148 THE BOOK OF FORESTRY 
charring. They also realized that proper seasoning 
made wood more lasting and it was a common custom 
to submerge timbers in sea water for a long time in 
order to increase their durability. 
It can be readily seen that increased durability of 
construction timber greatly reduces the cost for to 
the initial value must be added the expense of replacing 
decayed railroad ties, etc. Consequently it is true econ- 
omy to adopt measures which will prolong the life of 
structural timber and which not only diminish the total 
cost but also greatly reduce the drain upon our forests 
by permitting inferior woods to be used in place of 
those having greater durability. For years the railroads 
of the East would use no other wood for ties except 
white oak but finally scarcity of this species led to the 
use of yellow pine, red oak and chestnut. With the 
decrease in the supply of these three species most of 
the Eastern railroads are beginning to use beech and 
birch and other hardwood timber for ties which, how- 
ever, must be first treated with creosote before using, in 
order that rapid decay may be avoided. In the South 
large numbers of railroad ties are made from “old field 
pine.” These ties should be impregnated before being 
placed in the roadbed and on account of their softness 
should be protected by a rail plate in order to endure. 
Two general methods may be used in prolonging the 
life of wood. The first is seasoning, during which 
process a large amount of moisture is removed from 
the timber. The second method is chemical treatment. 
Effect of Seasoning.—While it may not appear at first 
glance that seasoning timber is a method of preserva- 
tion, nevertheless, its effect in increasing durability can- 
not be doubted. Fence posts and telephone poles which 
have been seasoned before using will show no signs of 
