74 BULLETIN 711, U. S. DEPARTMENT OF AGEICULTURE. 



assists the rigiring slingers with their work. The swamper works 

 just ahead of the rigginc men. knots the logs, fells small timber that 

 may be a source of danger to the crew, chops out the brush, and im- 

 proves the roads, so that the logs can be brought out without being 

 lumg up. "Wlien necessary, the sniper rounds off the under side of 

 the front end of the logs, so that they will slide over obstructions. 

 In rough country, where the logs are apt to roll and to be dragged 

 first on one side and then on the other, they are usually sniped all the 

 way around. The depth of the snipe depends partly on the size of 

 the log and" partly on the ground conditions, ranging from little or 

 nothing to 9 inches. The head rigging slinger is the hook tender's 

 assistant. Working alone or assisted by another rigging slinger, 

 sometimes two others, he unhooks the chokers from the butt chain 

 when the main line is returned, hooks up the new load of logs, and 

 starts it toward the landing. The principal duty of the choker men 

 is to put the chokers around the logs. The chaser, standing near the 

 butt chain block, signals to the engineer in case there is need for 

 stopping the engine. His principal work is to pass the load of logs 

 by the butt-chain block. The signal man. by means of signals, usually 

 given by pulling on a wire attached to the whistle of the yarder or 

 by an electrical device, transmits the order of the hook tender, rigging 

 slinger. or chaser to the engineer. 



KQUIPMENT. 



Ground Jogging enghies. — Engines used in swinging and roading 

 on the ground, as well as ground yarding engines, are dealt with in 

 this section. While their inclusion here is not exactly logical, clear- 

 ness and convenience of discussion make it advisable. 



Figures 29 and 30 show the compound-geared and tandem-drum 

 logging engines, the two standard types used for ground logging. 

 As a rule, the narrow-drum, compound-geared engine is used, the 

 compounding of the gears having proved the best method of securing 

 the proper relation between the two drums in regard to speed and 

 i:)ulling power. 



The wide-drum, simple-geared engine is also used, but principally 

 for SAvinging and roading. where high speed in the lines and large 

 drum capacity are of major importance. Wide-drum engines bear 

 special trade names, depending on whether they are adapted for yard- 

 i]ig and swinging or roading, the chief differences lying in the drum 

 propoi-tions and friction devices. The engines and boilers of a long- 

 haul road engine are. of course, larger than those of an engine adapted 

 to haul at relatively shorter distances. 



Probably no other class of machinery is called upon for such ex- 

 tremely severe service as logging engines. The demands made upon 



