ON THE STEENGTH OF PILLAES OF CAST lEON. 
863 
length being 7 feet 6f inches. To compare the results of this latter series of pillars 
with those of a larger kind in the present research, we will select three hollow pillars, 
among the least objectionable in the series, and two solid ones, and reduce their results 
to what they would have been if the pillars had been 1 inch diameter and 10 feet long. 
Pillars of Low Moor Iron, No. 3. 
Length. 
Diameter. 
Breaking 
weight. 
Value of X, or strength of 
a pillar 1 inch diameter and 
10 feet long, from formula 
W 
D3-55_^3-55 20‘7 
Value of X, or breaking 
weight of a pillar 1 inch 
diameter and 10 feet long, 
from formula 
_ W Z*'®* 
Hollow pillars...-^ 88f 
90f 
Solid pillars .. 
90| 
90f 
External diameter 
1'75 in. 
Internal diameter 
1- 11 in. 
External diameter 
2- 04 in. 
Internal diameter 
1*46 in. 
External diameter 
2-01 in. 
Internal diameter 
1-368 in. 
Diameter 1*76 in. 
Diameter 1*72 in. 
lbs. 
20937 
32413 
30789 
23179 
21995 
lbs. 
2230-7' 
2222-6 ^Mean 2166-5 
2046-3 
1937-61 
>Mean 1966-2 
1994-9 J 
lbs. 
2352-8' 
2369-7 >-Mean 2338-2 
2292-2 
2032-51 
^Mean 2061-4 
2090-3 J 
The length I is taken in feet =7-5625 feet. 
Comparing the results of the pillars in the abstract above, which are on Low Moor 
iron, No. 3, with those in the first Summary, which are on the same iron. No. 2, and 
taking the value of as a mean from the fu’st six hollow pillars, we have as below : — 
On the first supposition, that is, using the power 3-55 of the diameter, and 1-7 of the 
length, — 
From the first summary, 2028-7 lbs. for solid, and 2174-2 for hollow pillars. 
From the above abstract, 1966-2 lbs. for solid, and 2166-5 for hollow pillars. 
On the second supposition, that is, using the power 3-5 of the diameter, and 1-63 of 
the length — 
From the first summary, 2125-6 lbs. for solid, and 2321-6 for hollow pillars. 
From the above abstract, 2061-4 lbs. for solid, and 2338-2 for hollow pillars. 
These results are nearly in accordance with one another, and they show in both series 
of experiments, and according to both suppositions, that the hollow cylinders are some- 
what stronger than the solid ones ; which is attributable, no doubt, to the superior hard- 
5 u 2 
