BULLETIN 497, U. S. DEPARTMENT OF AGRICULTURE. 



GENERAL OBSERVATIONS. 



Before testing each specimen was weighed and measured. The 

 proportions of sapwood and summerwood were -also recorded. 

 After the test a sketch of each specimen was made showing the 

 failures and all natural defects. All large green beams were photo- 

 graphed after the test and the air-seasoned ones both before and 

 after the test, the four sides of the timbers being shown in each case. 

 All strength values obtained from the tests were calculated in pounds 

 per square inch and are given in tabulated form along with the other 

 test data. 



STRENGTH VALUES SHOWN BY THE TESTS. 



CAR SILLS. 



Tables 1 and 2 give the average strength values of green and air- 

 seasoned car sills of the commercial grades. These tables also in- 

 clude a comparison of the strength values of the different grades, 

 the values of the merchantable and common grades being expressed 

 in percentages of the values of the select grade. 



JOISTS. 



The results of the tests on green and air-seasoned joists are shown 

 in Table 3. The average values for all grades have been grouped 

 together. 



Table 3. — Results of tests of 2-inch by 10-inch by 16-foot joists, tuestem yellow 

 pine, 15-foot span, third-point loading. 









Weight per cubic 



Fiber 



Modulus 



Number 

 of 



Rings 

 per 



Moisture. 



fo 



)t. 



stress at 



elastic 



limit per 



of 



rupture 



per 









As 



Oven 



square 



square 









tested. 



dry. 



inch. 



inch. 







Per cent. 



Pounds. 



Pounds. 



Pounds. 



Pounds. 



46 



17.3 



35.8 



35.7 



26.4 



2,830 



4,272 



1 



28.0 



123.1 



55.2 



35.6 



4,047 



6,105 



1 



7.5 



20.2 



28.5 



21.0 



2, 147 



1,980 



33 



16.7 



13.2 



31.6 



28.5 



4,502 



6,640 



1 



29.0 



14.8 



37.7 



33.2 



7,025 



9,520 



1 



10.5 



12.2 



25.5 



22.5 



1,811 



2,320 



Modulus 



of 



elasticity 



per 



square 



inch. 



Green, all grades: 



Average 



Maximum 



Minimum 



Air seasoned, all 

 grades: 



Average 



Maximum 



Minimum 



Thou- 

 sands of 

 pounds. 

 1,266 

 1,705 

 731 



1,595 

 2,148 



1,088 



SMALL CLEAR PIECES. 



Tables 4 and 6 give the results of the bending tests on the clear 

 pieces taken from the tested car sills and joists. The results of tests 

 in compression parallel to the grain, on both large and small speci- 

 mens taken from the car sills, are contained in Table 5. The results 

 of tests on small specimens taken from the joists are given in Table 7. 

 Table 10 contains the results of a limited number of tests in compres- 

 sion at right angles to the grain made on clear pieces taken from the 

 tested car sills. 



