104 BULLETIN" 111, U. S. DEPARTMENT OF AGRICULTURE. 
averaged about 2,000 feet and were yarded an average maximum dis- 
tance of 900 feet. At another camp the main yarding lines used 
during a year averaged 5,000,000 feet. They were If -inch lines. The 
ground was practically level and quite free of down timber. The 
logs averaged about 550 feet in volume. At still another camp the 
IJ-inch main yarding lines used during a year averaged 4,500,000 
feet; the f-inch trip lines, 5,500,000 feet. The ground was badly 
broken up by potholes, hummocks, small ravines, etc. The topog- 
raphy was mixed, the ground being both hilly and level; where it 
was hilly, the logs were moved downhill. The volume of the average 
log was about 1,000 feet, and the average output per engine per 
yarding day about 40,000 feet. 
(h) Diameter of lines. — The size of lines used determines to a 
great extent their total cost and their life. 
The following recommendations have been made : 
That a l^-inch main yarding and a ik-inch trip line should be used on 10 by 
11 inch compound-geared yarding engines; a l§-inch main yarding and a f-inch 
trip line on 11 by 13 inch compound-geared yarding engines ; a lj-inch main 
yarding and a H-ineh or a f-inch trip line on 12 by 14 inch compound-geared 
yarding engines; and that a f-inch straw line be used on all engines. 
It was assumed that a 10 by 11 inch engine would be used in com- 
paratively level country where the difference in elevation would not 
exceed 75 feet, the largest log would not exceed 1,000 feet, and the 
maxinrum haul would not exceed 950 feet; that a 11 by 13 inch en- 
gine would be used in rolling country where the difference in eleva- 
tion would not exceed 150 feet, the maximum log would not exceed 
5,000 feet, and the maximum haul would not exceed 1,000 feet; that 
a 12 by 14 inch yarding engine would be used where conditions were 
more severe ; and that the yarding would be done uphill whenever 
possible. These sizes are larger than those generally used. It may 
be, however, that the increased output will more than offset the addi- 
tional cost for slightly larger cables. 
As a rule the size of main-yarding lines ranges from If to If 
inches; of trip lines from -J to f inches. In one camp, where the 
logs yarded averaged about 2,000 feet, the country being mountain- 
ous and badly broken up, lf-inch main yarding and f-inch trip lines 
were used. In another camp, where the logs yarded averaged about 
GOO feet, the country being practically level, yarding lines were 1J- 
inch and trip lines -J inch. In a third camp, where conditions were 
practically the same as those in the preceding camp, 1-J-inch main 
yarding and f-inch trip lines were used. In another camp, where the 
logs yarded averaged about 1,000 feet and the country was bad, the 
main yarding and trip lines were lj-inch and f-inch, respectively. 
In still another camp the following lines were used : A If -inch main 
line and a f-inch trip line with a compound-geared engine ; a 1 J-inch 
