298 IMPROVING THE ACCURACY OF TIMBER ESTIMATES 



to establish the total value of the stock on hand. It is not sufficient 

 to know the quantity of wood in the forest in terms of board feet or 

 cubic feet. The estimation of poles, ties and other piece products 

 by sizes and grades illustrates this need. An inventory requires a 

 statement of the total quantity of each class of product, and of each 

 grade or quality within that class, which has a different unit price or 

 value. 



Lumber grades differ enormously in value (§ 352), and the quantity 

 of separate grades of lumber which may be sawed from trees of different 

 ages and sizes differs as widely as their values. The estimation of the 

 amount of the different standard grades of lumber in standing timber 

 is as essential in determining its value as the measurement of the total 

 quantity in board feet. The neglect or inability of many foresters, 

 whose training was along lines of mechanical estimating (§ 223) to 

 determine the amount of the product by grades has done much to 

 withhold a recognition among practical cruisers of the great services 

 rendered the profession of cruising by foresters in contributing volume 

 tables and in systematizing the making of topographic maps. 



What is wanted is the estimation of the total quantity of timber 

 on a tract, separated into the amount of each of several standard grades, 

 covering the range of the products and sufficient to include practically 

 the entire cut and to determine its average value on the stump. This 

 problem is closely related to that of discounting for defects in that both 

 require a close observation of the character of the standing timber 

 rather than its mere dimensions. 



All defects which reduce the value of sawed lumber reduce its grade. 

 When these defects are of a character to reduce the grade below a certain 

 standard (§ 358, Appendix A), the material is no longer scaled under 

 the rule of sound scale. It may still be sawed and sold as lumber. 

 But when it ceases to hold together as boards it is cull. 



The deduction of a per cent of the total estimate for defects brings 

 the estimate into conformity with the quantitative " sound " scale. 

 The further separation into grades of the sound portion of the timber 

 which will be scaled and estimated, recognizes the influence of defects, 

 chiefly knots, but including other classes, such as wormholes, sound 

 stain, and twisted grain, which lower the grades and nature of the 

 log contents (§ 352, Appendix A). 



To determine grades, a knowledge of the results of sawing and the 

 study of logs as they are opened up and graded into products on the 

 sorting table is far more valuable than the experience gained in studying 

 the apparent defects of standing timber. This knowledge must then 

 be supplemented by a knowledge of the growth of trees in stands. 

 Open-grown trees, although large, are of low quality due to the presence 



