216 ME. W. EAIBBAIEN AOT> ME. T. TATE ON THE MECHANICAL PEOPEEIIES 
The fractm-e took place at «, fig. 1, and presented a regnlai- smooth conTex surface. 
No notch had been cut in this specimen. 
Experiment 2. 
AmwaXed Flint-glciss. 
Least diameter .... 0'50 in. 
Least area 0’196 sq. in. 
Breaking weight, 499 lbs. =2540 lbs. per square inch. 
Broke in the notch at t, fig. 1, which in this case was cut by the giindstone. It is 
possible that the exterior coat of glass may be stronger than its core, m which case e 
!bove specimen was weakened. In the next experiments the specimens were diawn 
thinner by heat. 
Experiment 3. 
Common Green Glass. 
Least diameter . . . • 0-53 in. 
Least area . . • • • 0-220 sq. in. 
Breaking weight, 639 lbs.=2896 lbs. per square inch. 
Experiment 4. 
White Crown-glass. 
Least diameter . . . • 0-54 in. 
Least area 0-229 sq. in. 
Breaking weight, 583 lbs. =2546 lbs. per square inch. 
Broke at shoulder ffi, fig. 1. 
The following Table exhibits at one view the results of these experiments, which, 
notwithstanding the objections to the method by which they were obtamed, appeal to 
be consistent with each other. 
Table I. — Tensile Strength of Glass Bars. 
Description of glass. 
Area of specimen, 
in inches. 
Breaking weight, 
in lbs. 
f 
0-255 
583 
Flint-glass s 
0-196 
499 
Green glass 
0-220 
639 
Crown-glass 
0-229 
583 
Tenacity per square inch, 
in lbs. 
2286 
2540 
2896 
2546 
in tons. 
1-02 
M3 
1-29 
M4 
It may be observed here, in anticipauon, uidt tnc 
the case of glass fractured by a direct strain in the form of bars, than when burst by 
intemal preLre in the form of thin globes. This difference is no doubt ““"b 
to the fact that thin plates of this material generally possess a higher 
stout bars, which, under the most favoui-able circumstances, may be but impeife > 
