PRACTICE OF TIMBER ESTIMATING 
203 
No. 2 (or Merchantable ) logs shall be not less than 16 
feet long and which, having defects which prevent their 
grading No. 1, in the judgment of the scaler, will be 
suitable for the manufacture of lumber principally in 
the grades of Merchantable and better. (Merchantable 
lumber must be free from knots or other defects in size 
or numbers such as to weaken the piece.) 
No. 3 (also called No. 2) logs shall be not less than 16 
feet long which, having defects that prevent their being 
graded higher, are, in the judgment of the scaler, suitable 
for the manufacture of Common lumber. 
Cull logs shall be any logs which in the judgment of 
the scaler will not cut 33^j per cent of sound timber. 
An essential to reliable timber grading is experience, a 
background of knowledge of the out-turn of similar tim¬ 
ber. In the next place, close examination of the stand 
is required as to the number and size of limbs and knots 
and for indications of these, or of other defects, that 
may lie beneath the surface. Age is a help here (these 
stands are commonly even-aged over considerable areas). 
Many cruisers go no farther than this and set percentage 
figures for log grades as the result of a broad judgment. 
When further detail is thought desirable, the volume 
tables before mentioned are of assistance, giving as some 
of them do for a tree of given diameter, taper, and mer¬ 
chantable length the percentage each successive 32-foot 
log bears to total contents. One standard volume table 
contains the following directions: — 
“Determine the percentages of the different grades as 
contained in a given percentage of the trees on each 40 
acres by selecting, for instance, an average tree on each 
tally and carefully determining the percentage of the 
different grades of logs contained in these sample trees 
and applying the average to all trees on the forty.” 
To illustrate, in the notes on page 199, 11 trees, 46 M 
feet, are scored down in the column of living fir, giving an 
average volume of 4200. 4 inches taper and 4 logs may fit 
this timber; if so, a tree yielding 4330 feet (see extract from 
taper table) gives a close approximation. Of such a tree 
a 32' butt log constitutes 37 per cent, the second log 28 
