TESTS OF ROCKY MOUNTAIN WOODS FOE TELEPHONE POLES. 7 
FIRE-KILLED LODGEPOLE PINE AND ENGELMANN SPRUCE. 
Twenty poles each of fire-killed lodgepole pine and Engelmann 
spruce were cut near Norrie, Colo., on a north slope at an elevation 
of about 10,000 feet. The area had been burned over by a light fire 
about 10 years 1 previously. The poles were largely free of bark, 
though a majority had patches here and there, showing that no serious 
weathering of the surface had taken place. 
METHODS OF TEST. 
Figure 4 shows the method employed in testing. The poles were 
supported about 1 foot from each end in bearing blocks (e, e) resting 
on rocker supports (f, d) 23 feet apart. The load was applied by a 
universal testing machine through a bearing block (t) 5 feet from the 
butt end of the pole, or 4 feet from the center line of the butt support. 
The rocker support (d) rested on a pier (c) built on the floor. The 
rocker support (/) rested at the center of the auxiliary beam (g), one 
end of which was supported by a rail (b) and two piers (a, a). The 
other end of the auxiliary beam (g) rested on a roller (k) in the center 
of the weighing platform (h) of the machine. As the load was gradually 
applied at t the pole deflected, and the scale at n, at the center of the 
span, moved down with respect to a taut spring (p) stretched be- 
tween pins driven into the pole on the neutral axis directly over the 
supports. The deflection of the pole at the load point was read on a 
scale (m), which gave the movement of the machine head (t) with 
reference to the platform (7i). 
Corresponding readings of the applied load, the deflection at the 
load point, and the deflection at the middle of the span were taken 
at convenient intervals, and plotted as shown in figure 5, until the 
pole was broken. The settling of the pole in the bearing blocks and 
deflection of the auxiliary beam (g) introduced slight errors in ftie 
determination of the deflection. The total error was estimated as 
less than 3 per cent within the elastic limit, and the only calculated 
results affected by this (which was practically constant for all the 
poles) are the stiffness factor and elastic resilience, both of which 
are comparable only with results from tests of the same nature. 
From each pole after test a 30-inch section ol clear wood was taken 
and cut into 2 by 2 inch sticks. These were tested in bending, in 
compression parallel to the grain, compression perpendicular to the 
grain, and shearing. The method employed in making these minor 
tests is discussed fully in Forest Service Circular 38 (revised). The 
purpose of these tests was to determine the influence of defects on 
the strength of the poles. 
The poles in each of the four lots were given consecutive numbers 
starting with 1, in order to distinguish between the individual poles 
of each lot. 
1 The date of the fire was obtained from local residents. 
