IMPORTANCE OF LUMBER, ASSOCIATED INDUSTRIES 



137 



4. Normally about 26,000 sawmills are engaged in the produc- 

 tion of lumber, and the number of logging operations to supply these 

 manufacturing enterprises is still larger, Pulp and paper, cooperage, 

 cross tie, veneer, naval stores, and other industries depend upon the 

 forests for their raw materials. 



5. Imports of forest products including paper amounted to more 

 than 400 million dollars in 1929, or nearly 1/10 of all our imports. 



FIG. 75. One of three Caterpillar Diesel tractors of 75 h.p. bringing in large size 

 ponderosa pine logs in northern California with Hyster- Willamette arch mounted 

 on Athey wheels. These machines burn about 21 gallons of Diesel fuel oil at 

 7 J /c per gallon, as against 48 gallons of 15c gasoline per 8 hours with 60 h.p. 

 gasoline units. The Diesel tractor has become widely used in recent years and 

 is replacing gasoline tractors for log skidding. 



The value of exports of forest products amounted to about 250 million 

 dollars. 



6. The annual transportation of forest products contributes about 

 170 million dollars normally to our railroad systems. Over 3,700,000 

 carloads of forest products were shipped in one year on our railroads. 



7. About 45 million dollars is spent annually for timber used to 

 mine coal and other minerals. The lumber industry employs more 

 than 3 billion primary horse power and is one of the four largest 

 industries. 



