TIMBER ESTIMATING. 59 
of purchase, and the seller wishes to obtain an adequate return 
for his material. In case of an ordinary lumbering operation where 
all merchantable material is taken, the quantity of wood products 
actually cut, as indicated by the log scale, or by measurement on 
the ground of the logs produced, gives a comparison by which the 
accuracy of an estimate of standing timber may be judged. 
The first products of the forest are: Logs intended for lumber, 
poles, ties, or posts, and cord wood. With few exceptions the tim- 
ber is converted into the product which has the greatest stumpage 
value or readiest sale, and it should be estimated in terms of this 
product—usually saw logs. 
The contents of logs are measured by log rules. No two of the 
many log rules now in use give equal volumes for logs of identical 
dimensions, and the extreme variation in the scale of a given lot 
of logs by different rules may be greater than 20 per cent. And 
even by the same rule, logs may be scaled closely or very loosely; 
liberal allowance may be made for defects or practically no allow- 
ance at all, according to the training of the scaler or the closeness 
of utilization. | 
The closeness with which the timber is utilized will vary in a 
given stand. As stumpage values increase, the aim wil! always be 
to secure more timber by cutting to smaller diameter, by lower 
stumps, and by utilizing up to a smaller diameter at the top. 
Species which were at first considered unmerchantable and later 
become valuable must be estimated. Improved transportation ~ 
facilities and the introduction of better logging machinery encour- 
age the removal of poorer classes of logs formerly unprofitable. 
For these reasons estimates have to be revised to correspond with 
advance in values, and old estimates, even if they were correct 
when made, are usually too small for present market conditions. 
Since there are so many and so various factors influencing the 
standard of measurement, it is seldom possible to make an estimate 
of timber which will come closer than within 10 per cent of the 
actual quantity standing on the ground. Yet an estimate must 
always be based on the present market conditions, except when 
the owner plans to hold his timber for an expected improvement in 
values, and therefore requires an estimate which wiii include 
species and sizes not now merchantable. 
