Fig. 21.

Fig. 22.

Collapsing pressure=382 lbs. per square inch.

This cylinder remained unbroken after sustaining a pres

sure of 500 lbs. per square inch.

EXPERIMENT 20*.

Cylinder V. Diameter 4.2 inches.

Length 22 inches.

In parts of an inch.

0.063

0.056

0.057

Thicknesses measured 0·055 > Minimum=0·055 inch.

Collapsed with 129 lbs. pressure per square inch.

* The experiments marked with an asterisk were not originally included in the calculations; but the results are strictly in conformity with those previously reduced.

EXPERIMENT 22*.

Cylinder X. Diameter 4.2 and 4.1 inches.
Length 22 inches.

Globe Z. Diameters 5.0 and 5·02 inches.

TABLE VII. — Summary of the Results of Experiments Resistance of Glass Globes to an External

on the Pressure.

TABLE VIII.-Summary of Results of Experiments on the Resistance of Glass Cylinders to an External Force.

SECTION V.

REDUCTION OF THE PRECEDING RESULTS.

I. Generalisation of the Results of Experiments on the Resistance of Glass Globes and Cylinders to External Pressure.

P = the external pressure in pounds per square inch to produce rupture.

D= the diameter of the globe or tube, as the case may be, in inches.

k = the thickness of the glass in inches.

p = the pressure P reduced to unity of thickness, viz. k='01 inch.

C, a, B, constants to be determined from the data supplied by the experiments.

Then for the globes we assume

where the exponent of the thickness is the same in both formulæ.

Hence we find for globes of the same diameter and also for cylinders of the same length and diameter

Taking the results of Experiments 1 and 2, we find a=1.35; from 5 and 6 we find a= =1·33; from 11 and 12 we find a=1.28; from 16 and 17 we find a=1.26;