Sti 7 esses on the Elastic Properties of Steel. 215 
tests tensile stresses o£ 0, 33, 50, 69, 81, and 100 per cent, of 
the normal elastic limit in tension were first applied, and 
while the material was under such tension it was tested in 
torsion. In the compression-torsion tests compressive stresses 
of 0, 33, 50, 83, and 100 per cent, of the normal elastic limit 
in compression were applied, and while the material was under 
such stress it was tested in torsion. A third series of tests 
were made on full-sized steel shafting, by first subjecting 
the material to a certain torque, and then, while under such 
torque, testing it in flexure. 
The writer hopes, at an early date, to be able to make a 
general review of all tests made, and to accompany it with a 
proper analysis of all data thus far obtained. In the mean- 
time the tests themselves are reported. 
Materials. — The material used in the tension-torsion and 
the compression-torsion tests was a grade of steel tubing 
furnished by the Shelby Steel Tube Co. The tension-torsion 
test-pieces were 32 inches long, one inch outside diameter, 
and 28/32 inch inside diameter. The compression-torsion 
test-pieces were 8 inches long and of the same size and 
thickness as the tension-torsion test-pieces. Simple tension 
tests showed the material to have the following physical 
properties: — Maximum strength 41,000 lbs. per sq. inch; 
elastic limit 21,000 lbs. per sq. inch and per cent, of elonga- 
tion in eight inches of 32. It was thoroughly annealed and 
of uniform thickness. The material used in the torsion- 
flexure tests consisted of solid nickel and mild carbon-steel 
shafting furnished by the Carnegie Steel Co. The nickel- 
steel was of the same chemical composition as the carbon- 
steel, except that it had about 3 per cent, of nickel. The 
pieces of shafting tested were 5 feet long and turned down 
to 1*5 inches in diameter. These pieces were squared slightly 
at the ends to provide for the application of the torque. 
Method of Test. — The method of testing pieces in tension 
while already under torsion has been explained (see Proc. 
Amer. Soc. Test. Mat. vol. v. p. 179). The same apparatus 
and arrangement of apparatus was made use of in testing in 
torsion while under tension. After the desired tensional load 
was applied, sufficient torsional load was put on to overcome 
the friction of the ball-bearing heads, and then the piece was 
tested in torsion. Elongations were measured with a Johnson 
extensometer and torsional deformations by means of an 
Olsen troptometer. Deformations in both tension and torsion 
were measured on an eight-inch gauge length. To determine 
the torque necessary to overcome the friction of the ball- 
bearing heads, due to the tensional load, the troptometer was 
set at zero, and sufficient sand added to the pails at the ends 
