or GLASS, AND THE EESISTANCE OE GLASS VESSELS TO COLLAPSE. 245 
^¥ 11611 ^= •043, as in most of the experiments on iron, then p= j2 ’ case, 
the strengths of the two cylinders will be nearly equal to one another. 
II. Generalization of the Results of the Experiments on the Resistance of Glass Globes^ 
Cylinders, and Ellipsoids to Internal Pressure. 
Let D = the diameter of the globe or cylinder, as the case may be. 
k = the thickness of the material in inches. 
a = the longitudinal sectional area of the material in square inches ; that is, in 
the direction of the line of rupture, or line of minimum strength. 
A = the longitudinal section in square inches. 
P = the bursting pressure in lbs. per square inch. 
T = the tenacity of the material in lbs. per square inch. 
Then we iind 
(15.) 
(16.) 
that is, — is a constant for vessels of the same material. This theoretical deduction is 
fully confirmed by the results of these experiments, as arranged in the following Table : — 
T.vble XIII. — Kesistance of Glass Globes, Cylinders, and Ellipsoids to an Internal 
Pressure. 
2 L 
MDCCCLIX. 
