MEASUREMENT OF LOGS AND OTHER FOREST PRODUCTS III 



forests of the South. It is the legal rule in Arkansas, Florida 

 and Louisiana. 



The Doyle rule is based on the formula 



.2 



(^)-' 



in which D equals the diameter in inches of the log at the small 

 end and L the length of the log in feet.^ A uniform allowance of 

 4 inches is made for slab. This is too great a deduction for 

 small logs and it is insufficient for large ones, consequently the 

 mill tally overruns the scale on small logs and barely holds out 

 on the large ones. 



A rule-of-thumb method for determining the contents of logs by 

 the Doyle rule is to subtract 4 from the diameter and square the 

 remainder. The result is the volume in board feet of a 16-foot 

 log. Other lengths are in proportion. This short-cut method 

 often proves of value to the field man since the contents of logs 

 can readily be determined by mental calculation. 



In southern yellow pine the mill cut overruns the log scale 

 by from 18 to 25 per cent. 



Doyle-Scrihner Rule. — This rule is used for scaling hardwoods 

 and occasionally for southern yellow pine. It is a combination 

 of the two preceding rules. The values for diameters up to and 

 including 27 inches are from the Doyle rule and those for 28 

 inches and over are from the Scribner rule. This combines the 

 lowest values of each rule, and is, therefore, not as accurate as 

 either alone. 



The Maine or Holland Ruler — This has been the principal 

 rule in Maine for many years and is not used elsewhere to any 

 extent. The values have been determined from diagrams show- 

 ing the number and size of i-inch boards, 6 inches and over in 

 width, that can be sawed from a given log. 



Sound spruce and pine logs of good quality, from 12 to 18 feet 



1 In some cases the published rule gives results varying nearly 3 board feet from 

 those determined by the use of the formula. The discrepancies do not appear to 

 bear any relation to a definite method and are undoubtedly due to errors which 

 have crept in since the rule was made. 



^ A copy of this rule is given in the Appendix. 



