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 



