POWER SKIDDING 217 



the logs around stumps or other obstructions, or to pull them 

 backwards until they are clear. As the logs reach a snatch 

 block on the road, the engine is stopped, the block opened, and 

 the cable removed. The block is then placed around the cable 

 behind the point at which the logs are attached. The logs then 

 are dragged to the succeeding blocks, and the process repeated. 

 When they reach the main road they are disconnected from the 

 chokers, grabs, or dogs, by a coupling-up man belonging to the 

 road-engine crew and the main cable is again returned for more 

 logs. 



A day's work for a yarding crew varies with the size of the 

 timber and the difficulties of logging, but averages from 40,000 

 to 60,000 feet. 



Coal and wood have been the common fuel for donkeys until 

 recent years. Oil burners are now in extensive use and electric 

 drive is rapidly being developed, although it is still in the experi- 

 mental stage. The advantage of fuel oil is that forest-fire danger 

 is eliminated, and operators claim the efficiency of the yarding 

 engines is increased from 15 to 25 per cent with a considerable 

 reduction in logging expense. Records of tests with fuel oil 

 reported at the Fourth Annual Meeting of the Pacific Coast 

 Logging Congress^ showed that on the operations of one company 

 the saving in the use of oil as compared with wood was from 

 9 to 17 cents per thousand feet due to increased efficiency, sav- 

 ing of good timber formerly used for fuel, and a reduction in the 

 force required to operate the yarder. 



The cables used for skidding are of plow steel, and their life 

 is dependent largely on the care they receive. When kept 

 properly oiled and operated under average conditions a main 

 cable will handle about 5,000,000 feet. 



A modification of the standard yarding engine is one known 

 as the Duplex logging engine.- This consists of four drums, 

 mounted in pairs and tandem on a 9-inch shaft; a single vertical 

 72-inch boiler and two 11- by 13-inch engines. It is in reality 

 two separate yarding engines under the control of one engineer. 



1 The Timberman, Portland, Oregon, August, 1912, p. 40. 



2 See The Timberman, July, 1911, p. 55. 



