GRADED VOLUME TABLES 195 



it causes a greater loss in the middle portions of logs which on account 

 of the presence of knots are of lower grade than the sound outer portion. 

 On the other hand, cat face and exterior defects reduce the amount 

 of clear lumber of upper grades. Unless such factors can be judged 

 correctly, the same per cents of grades must be accepted for defective 

 logs as are shown in the table for sound logs. 



It has been the common practice, in preparing graded volume 

 tables for hardwoods, to base the table upon the net sound contents 

 after deducting cull. Where sufficient typical sound logs of the larger 

 sizes cannot be obtained, the drawbacks of a table based on a partial 

 scale, i.e., culled, can be in a measure overcome by reducing this table 

 to per cent form as indicated above. Such a table should include a 

 statement of the basis on which it was made, the average per cent 

 of cull deducted, and the general character of the defects and influence 

 on the different grades. On this basis, its application to other timber 

 is possible.^ 



Graded log tables are of permanent value, and the utility of these 

 tables, if expressed in per cent, may be greater than is now imagined. 

 The permanence of such a table depends entirely on the maintenance 

 of the standard of grading, or grades of lumber on which the graded 

 table is based, hence such tables cannot have the permanent scientific 

 value of tables giving volume in standard units for sound trees. 



References 



A Volume Table for Hewed Railroad Ties, James W. Girard and W. S. Schwartz, 



Journal of Forestry, Vol. XVII, 1919, p. 839. 

 Graded Volume Tables for Vermont Hardwoods, Irving W. Bailey and Philip C. 



Heald, Forestry Quarterly, Vol. XII, 1914, p. 5. 

 The Ashes, Their Characteristics and Management, W. D. Sterrett, Bui. 299, 



U. S. Dept. Agr., 1915, p. 35. (Table based on per cents.) 

 Grades and Amounts of Lumber Sawed from Yellow Poplar, Yellow Birch, Sugar 



Maple, and Beech, E. A. Braniff, Bui. 73, Forest Service, 1906. (Table by 



per cents for Yellow Poplar.) 

 Assortment Tables, Mitteilungen der Schwarzerischen Centralanstalt ftir das forst- 



liche Versuchswesen, Vol. XI, 2 Heft, pp. 153-272. Review in Forestry 



Quarterly, Vol. XIV, p. 752. 

 Graded Log Tables for Loblolly Pine, W. W. Ashe, Bui. 24, North Carolina Geolog- 

 ical Survey, 1915. 



1 European investigations have shown that the per cent of total volumes which 

 is obtained in the different grades of product varies with the diameter but does 

 not differ appreciably with height. "In proportion as the shorter stem is less 

 in volume than the longer, the assortment contents decreases but the per cent 

 relation remains the same." Ref. Forestry Quarterly, Vol. XIV, 1916, p. 752. 



