194 VOLUME TABLES FOR PIECE PRODUCTS 



be determined by the amount of defect in the log as well as the grades 

 of lumber — the net, not the gross scale will be obtained. 



But the same objections hold against introducing into graded tables 

 the variable factor of the cull due to a great range of defects as have 

 operated to exclude such deductions from all standard tables. Hence 

 the only safe standard on which to construct such tables is sound logs. 



3. The grades of lumber are first determined in logs of given diam- 

 eters and lengths, from which graded log rules may be constructed. 

 Such rules are of course never used in scaling logs (§ 87) but solely to 

 aid in the determination of the average price to be paid for the contents 

 as scaled. 



4. The grades of lumber in trees of different sizes must be obtained 

 by correlating the sizes of the logs graded with the logs contained in 

 the trees. 



One standard method used in constructing such tables is to follow 

 the logs from different trees through the mill, by numbering the logs 

 in the woods, a process impossible without much delay except in small 

 jobs. 



Separation of butt logs and top logs is a less detailed method of 

 classification of logs. 



A third plan is to prepare separately the graded log table without 

 reference to the trees, and then determine the sizes of logs in trees of 

 different D.B.H. applying the grades to the given logs to get the grades 

 for the tree. Of the three methods, this is the most practical and use- 

 ful. In this the graded log table is the real basis, local graded volume 

 tables being constructed from this table for use in each different stand 

 of timber (§ 87). 



5. To show the actual contents of trees of each separate diameter 

 and height class, expressed in from four to eight standard grades would 

 call for a table of considerable bulk, and when in addition to this draw- 

 back the actual volumes shown are based on an arbitrary net sawed 

 output minus whatever cull happens to have been present in the logs 

 measured, the advisability of using such a form of standard table is 

 questionable. 



6. Where graded volume tables of greater permanent value are 

 desired the purpose of the tables will be accomplished by the following 

 simplification: 



a. Substitute per cents of sawed contents for actual sawed con- 

 tents for each grade of lumber scaled. 

 h. Substitute D.B.H. alone for D.B.H. and height, as the basis 

 of classification of the trees. 

 If these per cents apply to sound logs, they may require modifica- 

 tion in the case of defective timber. Where heart rot is prevalent 



