44 



A cubic unit, either the cubic foot or cubic meter, ultimately will 

 be in common use for the commercial measurement of timber. 

 This will come about with the increase of the value of timber. 

 When the whole log, including slabs, can be used, the owner can 

 not afford to sell his logs purely on a basis of an estimated product 

 in manufactured boards. If logs are bought according to their solid 

 contents, though they may not cost more, yet the buyer will feel 

 that he pays for the material he wastes and therefore will be more 

 eager to utilize it. 



There are a number of methods of determining the solid contents 

 of logs in cubic feet. The two methods in most common use for 

 commercial work are given in this book. Other methods, designed 

 for scientific work, are discussed at length in treatises on forest 

 mensuration. 



METHOD OF CUBING LOGS BY THE MEASUREMENT 

 OF THE LENGTH AND OF THE MIDDLE DIAMETERS. 



To cube logs, one method requires the measurement of the aver- 

 age diameter of the log at its middle point and the length. The 

 volume of the log is obtained by multiplying the area of the circle 

 corresponding to the middle diameter of the log by the length. Ex- 

 pressed algebraically : 



V=Bi X L, 



in which V is the volume of the log in cubic feet, B^ the area of the 

 middle cross section in square feet, and L the length in feet. 



EXAMPLE : Suppose a log to have a middle diameter of 15 inches 

 and a length of 30 feet. One finds in a table of areas of circles (giv- 

 ing the diameter in inches and the area in square feet) the area cor- 

 responding to 15 inches, namely, 1.227; then F=l. 227X30=36.8 

 cubic feet. 



This method is very simple, because it requires only two meas- 

 urements of the log the diameter at the middle and the length. 

 Tables showing the areas of circles in these units are readily acces- 

 sible, and also tables showing the cubic contents of logs of different 

 middle diameters and lengths, so that there is no computation 

 necessary. (See table 5.) 



Q, 



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