162 



REPORTS ON THE STATE OP SCIENCE. — 1915. 



Bending Test. — The specimen was turned to 0'4365-inch diameter 

 and subjected to a uniform bending moment. The deflection was 

 measured on a length of 4 inches by a sensitive piece of apparatus 

 supported on the specimen. 



r Bending moment at first yield . 



\ Maximum stress „ ,, . . 

 Final bending moment 

 Stress, assumed uniform over section 

 " E " from straight portion of curve 



168 lbs. -inches. 



9-18 tons per sq. inch. 



260 lbs. -inches. 



8-37 tons per sq. inch. 



30,400,000 lbs. per sq. inch. 



13,900 tons per sq. inch. 



Torsion Tests. — The diameter of the test piece was 0'4367 inch, 

 and the twist was measured on a length of 4*47 inches. A torque-twist 



Fia. 2. 



curve is given in fig. 2. The cui've deviates from the straight line 

 at a torque of about 120 lbs. -inches (3"27 tons per square inch) and 

 complete yield takes place at 240 lbs. -inches (5"31 tons per square inch 

 on the assumption of uniform stress distribution). 



This result was considered to be unsatisfactory, and another torsion 

 test was made on the specimen which had already yielded slightly by 

 bending. There appeared to be no straight line portion to the torque- 

 twist curve, a time effect was measured at 110 lbs. -inches (3'0 tons per 

 square inch), and final yield took place at 210 lbs. -inches (4"65 tons per 

 square inch on the assumption of uniform stress distribution). 



These results present certain difficulties. The tension test was 

 satisfactory and the data obtained are what would be expected from 

 the grade of steel and from the tests made by Mr. Cook. The 



