60 BULLETIN 711, TJ. S. DEPARTMENT OF AGRICULTURE. 
scriptive terms ; or the second and third hauls may be denominated 
" swinging.*' The terms are loosely used by the industry, however, so 
that for clear and accurate discussion, definition of terms is neces- 
sary, which in the very nature of the case must be more or less ar- 
bitrary. 
The term " yarding " in this bulletin is confined to the first haul, 
which takes the log at the stump. Swinging is considered as trans- 
portation that delivers the log from the yarding engine to a pole 
road, chute, railroad, or drivable stream. One or more engines, of 
either ground or overhead type, may do the work, but always in con- 
nection with very temporary improvements. Roading is considered 
as the transportation of logs by a logging engine or engines in con- 
nection with improvements that are to some extent permanent in 
character, such improvements consisting of pole roads, chutes, over- 
head cables, etc. 
YARDING. 
METHODS. 
Power yarding is done in three ways : First, with the log dragging 
on the ground and the haul-in or main yarding line leading along 
the surface of the ground from the yarding engine to the log: sec- 
ond, with the log dragging on the ground and the main yarding line 
leading from the yarding engine to a large lead block suspended 
near the top of a spar tree standing close by and thence out to the 
log ; third, with the log riding suspended, or partly suspended, from 
an overhead cable. The first system is known as ground yarding; the 
second, as high-lead yarding: and the third, as overhead yarding. 
In addition to these three yarding systems, there are a great num- 
ber of methods and a great variety of labor, equipment, and supplies 
used in yarding; more than in any other step in the logging opera- 
tion. 
FACTORS INFLUENCING THE OUTPUT. 
Yarding output, the chief element determining cost, is of utmost 
concern to both the operator and the timber appraiser. Influenced 
as it is by a great variety of factors, it is hard to estimate. Com- 
panies that use a bonus system have proved that abundantly, and 
they possess every advantage in the shape of records and time, aside 
from the inducement to make an intensive examination of the terri- 
tory. The appraiser, who must estimate yarding output at whole- 
sale and after a far less thorough examination, is at a great disad- 
vantage. Following are the factors to be considered. No attempt is 
made to present them in the order of their importance. They are 
treated in more detail under the specific methods. 
