24 BULLETIN 440, U. S. DEPARTMENT OF AGRICULTURE. 
bumper logs on one or both sides of the track. The cost differs with 
the amount of clearing and grading necessary. The average is from 
one-half to one day's work for a yarding crew, or from $20 to $40 
each, or say, 2 cents per 1,000. In the open stands of yellow pine a 
combined bucking chute and landing is used. The landing consists 
of three logs and a bumper log, and the chute is about 250 feet in 
length. The average cost is $100, or about 7 cents per 1,000. The 
most expensive type of landing is that used in a long logging opera- 
tion on very steep ground. A large excavation must be made in the 
upper bank of a railroad cut, and bucking chutes 250 feet long are 
built out in two directions. The average cost is about $300 each, or 
approximately 8 cents per 1,000. 
Equipment. — Donkeys are ordinarily classified by the size of the 
cylinders, the diameter being given first. The original yarding 
donkey was the Dolbeer or spool type, which is now used mainly for 
chute and trestle construction. The standard size Dolbeer has a sin- 
gle 6 by 12 inch cylinder and weighs about 8,000 pounds. The boiler 
is 36 by 6 inches and carries 160 pounds of steam. It is manufactured 
in San Francisco and the cost f. o. b. factory is about $1,000. This 
type has a spool for the yarding line and may have a single drum for 
the back fine. The usual maximum yarding distance is 800 or 1,000 
feet. 
Practically all the other machines used are return line. Ail of the 
engines have two cylinders and are connected by gears to the shafts 
of two drums, one for the yarding line and one for the back line. 
These gears may be either direct or compound. Compound gears give 
greater speed. The drums, placed either tandem or opposite, rotate 
upon their shafts and are held fast when pulling by means of frictions, 
which are applied by hand levers. The newer and larger yarding 
engines have steam frictions on the main drum. A spool or small 
friction drum may be attached to the shaft of the main drum for 
loading purposes. 
The boilers are upright, ranging in size from 48 inches in diameter 
and 118 inches in height to 72 inches in diameter and 144 inches in 
height. Some of the newer types have so-called extension fire boxes 
which give larger firing space. The boilers of the older types of 
engines carry about 160 or 165 pounds of steam. The newer types 
carry from 175 to 200 pounds. It is important in any yarder to have 
sufficient boiler space to keep up steam pressure, especially in the 
mornings or after showers, when the fuel is wet. 
Small machines, such as 10 by 11 inch tandem drum yarders, and 
9| by 10 inch and 9 by 10 J inch compound yarders, are used in the 
yellow pine stands on the east side of the Sierras. Light, rapid ma- 
chines which can be readily moved are required because the timber 
is small and the stand open. Machines of these sizes are usually sup- 
