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 otherrule. 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. 
