104 BULLETIN 711, U. S. DEPARTMENT OF AGRICULTUEE. 



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 1-^-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) Diametci' 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 IJ-inch main yarding and a ts-incli trip line should be used on 10 by 

 11 inch compound-geared yarding engines ; a l§-inch main yarding and a |-inch 

 trip line on 11 by 13 inch compound-geared yarding engines; a l^-inch main 

 yarding and a 1 J -inch or a f-inch trip line on 12 by 14 inch compound-geared 

 yarding engines ; and that a |-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 

 maximum 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 1^ to If 

 inches; of trip lines from ^ to ^ inches. In one camp, where the 

 logs yarded averaged about 2,000 feet, the country being mountain- 

 ous and badly broken up, If -inch main yarding and |-inch trip lines 

 were used. In another camp, where the logs yarded averaged about 

 600 feet, the country being practically level, yarding lines were 1^- 

 inch and trip lines ^ inch. In a third camp, where conditions were 

 practically the same as those in the preceding camp, 1^-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 1^-inch and f-inch, respectively. 

 In still another camp the following lines were used : A 1^-inch main 

 line and a f-inch trip line with a compound-geared engine ; a 1^-inch 



