LOGGING IN THE DOUGLAS FIR REGION. 65 
SHAPE AND SIZE OF YAKDING CHANCE. 
The shape of yarding chances, or the timber yarded to one point 
by one yarding engine, depends on the topography of the land. If 
the land is practically level, making it possible to gridiron the tract 
with railroads rather regularly laid out, the yarding chances are 
rectangular in shape, with the side bordering on the railroad about 
twice the length of the ends. This results in a square tract being 
3 7 arded to each end of the landing. Seldom, however, does the to- 
pography permit the blocking of yarding chances in this manner. 
As a rule they are very irregular in shape, being bounded by divides, 
gulches, or the range of practical }^arding distance. Figure 16 shows 
the shape of yarding chances in exceptionally good ground, while 
figure IT illustrates the usual irregularity. The chances in the latter 
case are larger than ordinarv. 
YAKDING DISTANCE. 
It is not practical in the abstract to say anything that will indi- 
cate the economical maximum yarding distance. Judging from the 
practice, the distance with the ground-yarding method ranges, under 
favorable conditions, between 600 and 900 feet, being generally about 
800 feet. If conditions are particularly favorable from the stand- 
point of the volume of the stand and the cost of railroad construc- 
tion and operation, the distance may be reduced to 500 feet. Too 
often, as has been pointed out, the topography of the country, by 
fixing the railroad location, fixes the distance that the timber must 
be transported by logging engines. In a given case it may be too 
long to constitute an economical yarding distance and not long 
enough to justify double hauling. It is then good practice to yard 
a distance greater than 900 feet. 
An important factor influencing the yarding distance, from the 
standpoint of both railroad and yarding costs, is the average stand 
of timber per acre. The following distances have been recommended 
as a general basis of calculation : 
(1) Twenty to forty thousand feet of timber per acre, 1,200 feet 
maximum yarding distance. 
(2) Forty to sixty thousand feet of timber per acre, 1.100 feet 
maximum yarding distance. 
(3) Sixty to eighty thousand feet of timber per acre, 1,000 feet 
maximum yarding distance. 
(4) Eighty to one hundred thousand feet of timber per acre. 
900 feet maximum yarding distance. 
61361°— Bull. 711—18 5 
