_Marking the Timber for Cutting._ In order to insure a proper restocking of the ground, all live trees must be marked or otherwise designated by a Forest officer before cutting can commence. Usually from 1/10 to 1/3 of the stand is reserved, either scattered over the entire tract or distributed in groups. These trees are left for various reasons, depending upon circumstances. The most important consideration is, of course, to leave enough seed trees to restock the cut-over area. On steep slopes a certain number of trees must be left to protect the watershed and to prevent the erosion of the soil. Many species of trees are subject to windthrow when the stand is thinned out. To counteract this tendency a sufficient number of trees must be left to prevent the wind from getting an unobstructed sweep. In many semi-arid portions of the West additional trees must be left standing to protect the forest from excessive drying and to prevent the ground from being occupied by useless tree weeds and brush. Often, especially along highways, trees are left for their scenic effect. From an economic standpoint it is important sometimes to leave trees in order to make a second cut worth while. Where only dead timber is purchased, and no living trees are cut, or where patches of forest are to be cut clean, Forest officers, instead of marking every tree to be removed, blaze and mark a boundary of the cutting area or patch and instruct the purchaser accordingly. Where individual trees are marked they are blazed and stamped "U. S." next to the ground on the lowest side of the stump. Additional blazes may be made several feet above the ground whenever desired by the purchaser for the convenience of his "fallers" or where deep snow may conceal the lower mark from the "fallers." Where both kinds of blazes are used, one man, in fairly dense pine timber, can mark from 500 to 1,000 trees in a day. Under no condition may unmarked or undesignated trees be cut by the purchaser. The system of marking and the proportion of the timber to be cut is explained to purchasers by marking sample areas before the contract is executed. The cost of logging under the methods of marking adopted is compensated fully in the stumpage appraisal. _Scaling, Measuring, and Stamping._ Unless timber is sold by estimate, it must be scaled, counted, or measured before it is removed from the cutting area or place agreed upon for this purpose. In addition it must be stamped by a Forest officer with a regulation marking ax or similar instrument. Payment is made upon the actual scale, count or measure, with due allowance for defect. All National Forest timber is sold under specifications which are in accordance with those in commercial use, such as logs by the thousand board feet, ties by the piece, poles by length and top diameter, shingle bolts by the cord, and mining timbers by the linear foot. All logs are scaled at the small end.