IO Forest Mensuration 



saw will obtain the following actual number of feet b. m. (in 4/4 

 thickness) : 



(a) from 12 foot logs: D ' X ^ 12 X 8 , almost equal to D* X .5 



(b) from 14 foot logs: P X 0.78^X 14 X 



D' X 0.78 X 16 X 8 . 

 (C) from 16 foot logs: - , almost equal to D'X-? 



Hence it can be stated generally, for logs of medium length "L," that 

 their contents in band-sawed inch lumber approximate 



D 2 L 2 



X feet b. m. 



10 A 2 



PARAGRAPH XVII. 



STANDARD RULES. 



The standard rules do not estimate the contents of a log according to 

 output in board feet, but compare the log with a local average log. Such 

 average logs used to have, in the Northeast, formerly, a diameter of 

 either 19 inches (Adirondacks) or 22 inches (Saranac River) or 24 

 inches, and were in all cases 13 feet long. 



The 19 inch standard log rule is known as Dimick's rule. Here the 

 "standard" or "market" is a log 13 feet long and 19 inches thick. On a 

 22 inch base it is 13 feet long and 22 inches thick. On a 24 inch base 

 it is 13 feet long and 24 inches thick. 



The standard contents of a given log are found by dividing the cubic 

 volume of the standard log into the cubic volume of the given log. 



d* X h 



v (in standards) equals: 



19* X 13 



Scientifically and mathematically the standard rules are superior to 

 the board rules. One market, at a 19 inch base, is generally considered 

 equivalent to 200 board feet; at a 22 inch base, to 250 board feet; at a 

 24 inch base, to 300 board feet. 



It is easily shown that the output of small logs is not as badly under- 

 estimated, and the output of big logs not as badly over-estimated on the 

 basis of standard rules, as is the case when Doyle's rule alone is applied. 



PARAGRAPH XVIII. 



CUBIC FOOT-RULES. 



In a third group of rules, a new unit, the "artificial cubic foot," is 

 introduced. This group of rules is established by law in Maine and New 

 Hampshire. (See Graves' Handbook, page 45.) 



