TESTS OF ROCKY MOUNTAIN WOODS FOR TELEPHONE POLES. 27 
by 12 inch posts set in the ground. The load was applied to the 
top of the pole, by means of a winch, at a rate of 1 foot per minute. 
A direct-reading dynamometer was placed in the line connecting 
the winch with the top of the pole. The top end of the pole was 
supported on a dolly with truck casters which traveled on a piece 
of sheet iron, thus eliminating friction. Readings of the movement 
of a nail driven into the top of the pole were taken for each 100 
pounds increment of load. 
The Pacific Telephone & Telegraph Co. has kindly permitted the 
use of their test data, and Table 7 is compiled from their report. 
Comparison of the equivalent top load in Table 2 with the top load 
for 7-inch by 25-foot poles in Table 7 shows a difference of only 5 
per cent, while the calculated stresses are about 20 per cent greater 
for the Forest Service results. This difference, as already stated, 
is probably due to the different methods used, both for calculating 
the stress and for supporting the butt of the pole. 
Reference to Table 7 shows that there is no consistent variation 
when poles of the same top diameter but of different lengths are com- 
pared. However, Table 8, compiled from Table 7, shows a very 
marked relation between top diameter and top breaking load in the 
three classes of poles tested by the Pacific Telephone & Telegraph Co. 
Table 7. — Results of pole tests made by the Pacific Telephone & Telegraph Co. 
WESTERN RED CEDAR FROM IDAHO. 
Length. 
Number 
of poles 
tested. 
Average values of— 
Top di- 
ameter. 
Weight 
of poles. 
Weight 
per cubic 
foot. 
Mois- 
ture. 
Rings 
per inch. 
Sap. 
Top load 
at failure. 
Modulus 
of rup- 
ture. 
Inches. 
6 
7 
8 
6 
8 
7 
8 
9 
Feet. 
25 
25 
25 
30 
30 
30 
35 
35 
35 
3 
4 
3 
4 
4 
3 
3 
3 
3 
Pounds. 
205 
244 
282 
283 
344 
382 
477 
471 
522 
Pounds. 
22.0 
23.0 
22.9 
22.4 
26.1 
23.4 
22.1 
19.4 
21.5 
Per cent. 
9.4 
9.2 
10.2 
13.6 
10.0 
9.1 
8.1 
10.4 
10.2 
13.7 
23.0 
18.3 
20.1 
23.3 
23.4 
19.3 
18.5 
22.6 
Per cent. 
38.0 
27.6 
26.3 
28.1 
24.5 
21.4 
40.8 
25.7 
24.9 
Pounds. 
1,853 
1,948 
2,667 
1,590 
2,434 
2,740 
2,000 
2,125 
2,992 
Lbs. per 
sq. in. 
6,221 
5,712 
5,290 
5,126 
5,549 
5,308 
5,080 
4,391 
4,755 
WESTERN RED CEDAR FROM OREGON AND WASHINGTON. 
6 
25 
3 
204 
24.1 
8.7 
24.4 
41.6 
1,470 
5,525 
7 
25 
3 
213 
19.8 
15.1 
6.6 
41.2 
1,625 
4,481 
8 
25 
3 
238 
19.8 
18.0 
9.5 
30.1 
2,072 
4,816 
6 
30 
3 
255 
21.7 
17.0 
7.2 
36.8 
1,352 
5,784 
7 
30 
3 
240 
18.8 
7.4 
9.3 
33.3 
1,597 
7,006 
8 
30 
3 
395 
22.8 
15.4 
11.3 
29.2 
2,385 
3,146 
7 
35 
3 
331 
21.1 
9.2 
8.0 
32.7 
1,712 
6,408 
8 
35 
3 
546 
24.6 
34.0 
6.8 
38.2 
1,888 
4,349 
9 
35 
3 
597 
24.8 
11.6 
24.3 
17.4 
3,257 
5,665 
