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. 



Riags 

 per inch. 



Sap. 



Top load 

 at failure. 



Modulus 

 of rup- 

 ture. 



Inches. 

 6 

 7 

 8 

 6 

 7 

 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 



Lis. 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 



