MEASUREMENT OF STANDING TIMBER IN THE TREE 9 



poles, staves and other piece products are customarily used as units for 

 timber estimating, when the timber is to be used for these purposes. 



Thus the standard commonly sought in America for measuring stand- 

 ing timber is the net merchantable volume, which results from deducting 

 all forms of waste in manufacture from the total contents of the tree. 



There is but one accurate method of measuring this net contents, 

 and that is to postpone the measurement until the timber is logged 

 and manufactured into boards or other products. Since a purchaser of 

 standing timber is always conservative wherever a doubt exists, it is to 

 the owner's interest to sell on the basis of actual mill cut of boards or 

 output of other products, whenever this is possible. This basis is 

 often used in regions where the timber is cut by small portable mills, 

 located in or near the tract and where small amounts are purchased. 



15. Measurement of Standing Timber Postponed till after Logging. 

 Where the logs must be driven down streams or hauled long distances 

 by the purchaser, this basis becomes impractical both l^ecause of the 

 delay in settlement of account and the difficulty of checking the output 

 of lumber. The timber owner is thus forced to substitute a log scale for 

 a mill tally of lumber. This scale is always based on some log rule agreed 

 upon beforehand, and may or may not give results coinciding with the 

 actual sawed output. If the log rule is known to be inaccurate, the 

 excess or deficiency of manufactured products can be ascertained only 

 by a comparison of the mill tally with the log scale. Such comparisons 

 will give an idea of over-run or under-run (§46). The owner can then 

 adjust the price in subsequent sales of logs according to the difference 

 between the scaled contents of his logs and their probable output in 

 sawed lumber. 



16. Measurement of Standing Timber in the Tree. But even the 

 log scale is inapplicable when standing timber is purchased in large 

 amounts and a long period is required for completion of logging. The 

 owner desires prompt payment even if based on a less accurate measure- 

 ment of volume. The volume of the standing timber must be measured 

 as well as possible, and since, at best, only the diameter of the trees 

 together with a few heights can be actually determined and the rest of 

 the work is done ocularly or by guess, the result is only a rough estimate. 

 This method has given rise to the term Timber Estimating. The prin- 

 cipal sources of error in timber estimating lie in the effort to arrive at the 

 net merchantable contents minus waste, in the use of inaccurate and 

 variable standards of log measure for this purpose, and in the difficulty 

 and cost of determining even the superficial dimensions of standing trees. 

 This leads to short-cut methods, approximations and guess work and 

 calls for the development of system and of personal skill. One improve- 

 ment in timber estimating widely used by foresters is the tree-volume 



