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JOURNAL OF FORESTRY 

 Table 4 — Top Cutting Limit in Inches. 



The discrepancies are striking. It is obvious that the top diameter 

 cut in this region is a matter of the individual judgment of the operator 

 and that the individual judgments of two operators may be far apart. 

 It is also obvious that if the volume table is built according to one 

 standard and the estimate made according to another, serious errors 

 will result. Suppose, for instance, a cruiser had based his conception 

 of what constituted a merchantable top on operation A and estimated 

 heights accordingly, but computes his estimates by the standard district 

 volume table. By the District 5 taper table for western yellow pine, 

 it will be seen that a 46-inch 7-log tree would be measured as but 6 logs 

 high. It would contain 4,600 feet board measure, but he would read 

 from the table the volume of the shorter tree, or 4,200 feet board 

 measure, an error of 9 per cent. If, on the other hand, a new volume 

 table were constructed on operation A and were used by a cruiser 

 whose ideas were fixed from observing operation B, the error would 

 be in the opposite direction, and perhaps reduced, but still in the neigh- 

 borhood of 6 per cent, a figure far too great to be accepted with 

 complacency. 



It was doubtless with this difficulty in mind that the makers of vol- 

 ume tables based on variable tops have appended a list of average top 

 diameters as found. But this is of little value to the estimator. In the 

 first place, the range is not the same for any two species, and it would 

 be somewhat of a feat of memory to carry in mind the five sets of 

 figures most necessary for use in the Sierras or the nine required in 

 parts of the northern Rockies. Such figures are moreover often mis- 

 leading. Chapman has pointed out that the used top limit tends to de- 

 crease with height within each diameter class. The rate of decrease 

 seems to vary widely with the whim of the logger, and very great con- 



