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Forestry Quarterly 



with several other figures upon which several rules of thumb are 

 based. When the computations were completed it was found 

 that the volume in each size class checked very closely with the 

 volume as obtained by averaging the scale of the butt and top 

 logs and multiplying by the number of logs, using 16 feet as a 

 standard log length. This rule is reported as being considerably 

 used by a number of Minnesota pine cruisers. In the preceding 

 table each left-hand column shows the average volume of a group 

 of trees ; the right-hand column shows the rule of thumb result 

 for the same group. 



These results indicate an average difference of about one per 

 cent in timber of this size, with a maximum difference of about 

 13 per cent in individual trees. 



The following is a comparison of 59 Douglas fir trees ranging 

 in diameter from 31 to 52": 



131,120 



127,580 



The result by rule is 3 per cent low. Greatest difference 16 per cent. 



