304 REPORTS ON THE STATE OF SCIENCE, ETC. 
of the elastic constants for the material was made. Young’s Modulus (for 
longitudinal stress) was found from the longitudinal extension in a cylindrical 
bar, and Poisson’s Ratio from a measurement of the lateral contraction of the 
same bar by the instrument used on the tubes, axial loading shackles being 
employed to secure uniformity of stress. The values thus found were 
E=29°88 x 10° Ib. per sq. in. 
1 0-295. 
m 
The results are also plotted in fig. 9, and it will be seen that the experimental 
results follow closely the theoretical curve. The small discrepancy which 
appears at points remote from the flange is entirely accounted for by the fact 
iae-2= en 
24 SS 
py O-= -0--—-9---9-- 
23 Observed Displacement 
aA 
Radial Displacement 
bP ON 
Listance trom Flange (ins. 
Oo os o2 os og os oO-s 
Fic. 9. 
that the actual extensions were measured on the outside of a tube of appreciable 
thickness, whereas the theory assumes uniform stress across the walls. Thus, 
the radial extension at the outside of a plain tube is given by 
PR’ (2- E Re 
m) RP 
where R’ and Ro are the external and internal radii respectively, giving, with the 
present data, a value 23.95 x 105, almost identical with that observed in the test. 
The discrepancy near the flange is probably due to errors in the assumptions 
involved in the calculation of the displacement of the flange. The point of 
maximum displacement is situated at a distance of about .28 in. (as nearly as 
can be measured) from the flange, the calculated distance being .276 in. 
