VARIOUS LOG RULES. 25 



The Doyle Rule. 



The Doyle Rule is variously known as the Connecticut River 

 Rule, the St. Croix Rule, the Thurber Rule, the Moore and Bee- 

 man Rule, and the Scribner Rule — the last name due to the fact 

 that it is now printed in Scribner's Lumber and Log Book. It is 

 used throughout the entire country, and is more widely employed 

 than any other rule. It is constructed by deducting 4 inches from 

 the small diameter of the log as an allowance for slab, squaring one- 

 quarter of the remainder, and multiplying the result by the length 

 of the log in feet. 



The important feature of the formula is that the width of slab 

 is always uniform, regardless of the size of the log. This waste 

 allowance is altogether too small for large logs and is excessive for 

 small ones. The principle is mathematically incorrect, for the 

 product of perfect logs of different sizes follows an entirely different 

 mathematical law, and it is, therefore, astonishing that this incor- 

 rect rule, which gives wrong results for both large and small logs, 

 should have so general a use. 



Where the loss by defects in the timber and waste in milling have 

 accidentally about balanced the inaccuracies of the rule, fairly 

 accurate results have been obtained. Frequently, however, 

 mill men recognize the shortcomings of the rule and make correc- 

 tions to meet their special requirements. In general, the mill 

 cut overruns the Doyle Rule log scale by about 25 per cent for short 

 logs 12 to 20 inches in diameter; and for long logs with a small 

 top diameter the overrun is very much higher. 



