of Metal Rods with rounded ends. 
2S. f 
Sta tic tests of Copper Specimen, 
Length 18". 
Mean diam. ... -4985". 
Weight 1124 lbs. 
Density 553 lbs. per cub. ft. 
Extensonieter test. 
Calibration of Instrument... 1 div. = 1/960". 
Length under test 8". 
Load (lbs.) 
Reading 
Difference 
Return 
Difference 
0 
7-19 
0 
7-13 
- -06 
250 
7-70 
•51 
7-67 
•48 
500 
8-22 
1-03 
8-26 
1-07 
750 
8-80 
1-61 
8-85 
1-66 
1 000 
9-37 
2-18 
9-42 
2-23 
1250 
9-95 
2-76 
10-00 (5-20) 
2-81 
1500 
10-51 (5-71) 
3-32 
5-76 
3-37 
1750 
6-30 
3-91 
6-30 
3-91 
2000 
6-85 
4-46 
6-85 
4-46 
Plotting, we see that 1750 lbs. give 4 divs. extension. 
8 x 960 x 1750 x 4 
E = 
x 7 r x ( - 4985) 2 
= 17,220,000 lbs. per sq. in. 
Hence 
17,220,000 x 32 18 x 144 
p v 553 
= 12,010 ft. per sec. 
19—2 
