BOARD MEASURE 
145 
log contains 2 ft. B. M. per foot of length, an 8-inch log 
2j ft., a 9-inch log 3 ft., a 10-inch log 4 ft. 
One notable thing about the New Brunswick rule is that 
taper is allowed for in lengths over 24 feet. 
7. Quebec Rule. This is the legal rule for measuring 
logs in the province of Quebec. Values are close to the 
Scribner Rule; in many cases they are identical. The 
figures were derived by plotting. 
8. Theory of Scale Rules and Clark’s International 
Log Rule. The theory of the measurement of saw logs 
in board measure has been more carefully studied by 
Dr. Judson F. Clark 1 than by anyone else, and a rule 
called the International Log Rule was devised by him, 
on the basis of this reasoning, which he also tested at 
the saw. The main points in this study are as follows: 
Taper of Logs. While logs exhibit a great variety of 
taper, it has been found (1) that rough logs taper more 
than clear, smooth logs, so that quality tends to neutralize 
taper; (2) that average taper does not differ greatly in dif¬ 
ferent localities or with different species. This average 
taper as a result of much measurement is found to be 
safely 1 inch in 8 feet. This in modern economical mill 
practice increases the yield of lumber in the form of side 
boards, and the above stated allowance for taper is there¬ 
fore introduced into the rule for all lengths over 8 feet. 
Crook and Sweep. In this study due allowance was 
made for irregularity of surface, and crook averaging \\ 
inches in 12 feet of length, found to be characteristic of 
white pine logs on the Ottawa River, was counted normal. 
Above the limit of 1^ inches in 12 feet, any given degree 
of crook was found to affect the product of small logs more 
than of large logs, and that in proportion to their diameters. 
That is to say, a crook of 3 inches in 12 feet throws out 
twice as great a percentage from a 10-inch log as from one 
20 inches in diameter. 
Shrinkage and Seasoning. Logs are commonly scaled 
green, while sawed lumber must hold out on a survey made 
when it is dry. In computing his. rule Dr. Clark figured 
that boards would be cut 1 T V inch thick to allow for this. 
1 See Forestry Quarterly, Yol. IV, No. 2. 
