OF GLASS, AND THE EESISTANCE OF GLASS VESSELS TO COLLAPSE. 
241 
Sectton V.— EEDHCTION OF THE PEECEDING EESULTS. 
I. Generalization of the Mesults of Experiments on the Resistance of Glass Globes and 
Cylinders to External Pressure. 
Let us assume — 
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. ^=-01 inch. 
C, a, |(3, constants to be determmed from the data supplied by the experiments. 
Then for the globes we assume 
( 1 -) 
and for the cylinders 
P 
C'A« 
( 2 .) 
where the exponent of the thickness is the same in both formulse. 
Hence we find for globes of the same diameter and also for cylinders of the same 
length and diameter, — 
log Pi -log Pg 
log A, -log ^2 
Taking the results of Experiments I. and II., we find 05=I-35; from V. and VII. we 
find a=l-33; from XI. and XII. we find a=l-28; from XVI. and XVII. we find 
«=1‘26 ; and from XV. and XIV. we find a = 2. Hence we get for the mean value of a, 
a=i{l-35+l-33+I-28+l-26+2} = I*4. 
Again, the following formula enables us to reduce the pressure P, of the cylinders as 
well as of the globes, to unity of thickness, 
logp=logP — alog(IOO^) (4.) 
Making these calculations, we obtain the following Tables of results : — 
Table VIII. — Reduction of the Results of Experiments on the Resistance of Glass 
Globes to unity of thickness. 
Number of 
experiment. 
D. 
Diameter, 
in inches. 
k. 
Thickness, 
in inches. 
P. 
Collapsing pres- 
sure, in lbs. per 
square inch. 
p- 
P reduced 
to unity of 
thickness. 
I. 
5-05 
•014 
292 
178 
11 . 
5-08 
•018 
410 
168 
III. 
4-95 
•022 
470 
156 
IV. 
5-60 
•020 
475 
180 
V. 
8-22 
•010 
35 
35 
VI. 
8-20 
•012 
42 
32-54 
VII. 
8-20 
•015 
60 
34-01 
