NATIONAL FOREST RESOURCES 183 



timber the maximum stump height is ordinarily 

 ixed at 18 inches, and merchantable timber must be 

 jsed to a specified diameter in the tops, which is ad- 

 justed for each species in accordance with local 

 nanufacturing and market conditions. The officer 

 n charge of the sale is authorized to vary the stump 

 icight and top diameter in individual cases when 

 ;hose specified in the contract are not practicable. 

 Fhe tops must be trimmed up and, as a rule, brush 

 nust be piled and burned, or burned without piling 

 mder the direction of Forest officers. Merchant- 

 ible timber which is not cut and removed and 

 mmarked trees which are cut must be paid for at 

 louble the specified stumpage rates. This extra 

 ;harge serves as a penalty. 



All camps, buildings, railroads, and other im- 

 provements necessary in logging and manufactur- 

 ng the timber may be constructed upon National 

 forest land without charge. Railroads which open 

 ip inaccessible regions may be required to be made 

 :ommon carriers or to transport logs and lumber 

 'or other purchasers or for the Government at 

 easonable rates. 



Since fire protection is one of the most important 

 hities of the Forest Service, provision is made in 



