TIMBER SLIDES AND CHUTES 275 
placed opposite each other. The holes in which the goose-necks 
are fitted are bored entirely through the slide timbers so that 
dirt cannot accumulate in them. When not in use the goose- 
necks may be removed or dropped into notches cut into the 
slide timbers for that purpose. 
Another form of brake has a log one end of which is pivoted 
to a framework erected above the slide. The free end is armed 
with spikes that drag on the logs as they pass under them. 
On long slides which have both very steep and slight pitches the 
use of annual draft for moving logs on the slow places is at times 
impracticable, especially in summer, because of the long steep 
climb from the lower to the higher elevations. Donkey engines 
placed at the foot of slides have proved successful both in holding 
logs back on steep grades and in pulling them over level stretches. 
A |-inch line is used and, in a tow of from 6 to 10 logs, the 
main cable is attached both to the rear and the front logs. It is 
necessary to select large round logs for the front and rear, other- 
wise the tow has a tendency to buckle when being pulled along 
the slide. Straight chutes are essential when a yarding engine is 
used because logs will leave the chute when the pull comes on a 
curve. The greatest success in the use of a donkey engine in 
connection with log slides is in dry trailing chutes. The daily 
capacity of one slide in Idaho which was 2000 feet long was 
from 20,000 to 30,000 board feet. 
The control of logs on a chute so steep that the logs either left 
the slide before they reached the bottom or were badly damaged 
at the bottom by breakage was solved by an Oregon logger in 
the following manner.^ The chute was 1600 feet long and the 
difference in elevation between the head and foot of the slide 
was 600 feet. A 6 horse-power gasoline engine was installed 
at the head of the slide and belted to the shaft of a donkey drum, 
which was equipped with a hand brake and a friction clutch. 
The engine was run continuously, power being transmitted from 
the shaft to the drum by the friction clutch. A ^^(j-inch cable 
was wound on the drum and to the free end a 14- by 40-inch 
round hold-back block was attached to the under side of which 
a 4- by 6- by 30-inch rudder was fastened which served to keep 
the hold-back block in position. The cable was attached to 
the base of the front end of the hold-back block and then carried 
1 The Timberman, March, 1915, p. 36. 
