WASTE, DEFINITION AND MEASUREMENT 179 



there arises a difference between the definition of merchantable length, 

 and used length. Merchantable length is the total length of a stem 

 which can be used under given conditions. Used length is the total 

 length of a stem actually utilized in commercial operations. There 

 is therefore no fixed or absolute merchantable length, since the very 

 definition of the term " merchantable " indicates that the product 

 must be salable. When an operator is actually utilizing all the material 

 that he can manufacture or market at a profit used length and merchant- 

 able length coincide. 



150. Waste, Definition and Measurement. Waste is therefore 

 defined in two ways. First, there is the unavoidable waste in twigs, 

 branches, stump and top, that cannot be used under existing economic 

 conditions, logging costs, and markets. A better term for this material 

 is refuse. This waste was large in earlier periods and tends constantly 

 to diminish. Second, there is avoidable waste, caused by the fact 

 that the markets and logging possibilities have changed faster than 

 the logging practice. During the war this form of waste increased in 

 certain sections due to the inefficiency, indifference and independence 

 of woods labor. The amount of this avoidable waste is somewhat a 

 matter of judgment. When waste is demonstrated, practice tends 

 to take up the slack, and used lengths are readjusted to coincide with 

 merchantable lengths. 



The unavoidable waste is usually taken as the difference between 

 the total and merchantable volumes of the bole, excluding branches. 



For tops, the paraboloidal formula V= J is used, while for stumps, 



the cylindrical contents of the stump based on its upper area is usually 

 accepted in place of its actual total volume. 



The avoidable waste represents the cubic volume of the top section 

 between the upper limit of used length and the merchantable diameter 

 limit, plus the cylinder representing the difference between actual 

 height of stump and height to which it should have been cut. 



A more complicated method applied to board-foot contents is to 

 re-scale the contents of the tree, measuring the top diameter of each 

 log at a point lower than the existing point by the difference in stump 

 height. The difference in total tree scale so obtained is regarded as 

 indicating the waste. 



151. Defects or Cull. For pulpwood, defective or rotten pieces are 

 not merchantable. This raises the question of cull or deductions from 

 the cubic volume table. The question is far more serious for board- 

 foot volume tables. No such deductions should be made for cull in 

 the volume tables themselves, especially in standard tables. The cull 

 per cent varies without any reference to tree form or total volume. 



