ON THE STEENOTH OF PILLAES OF CAST lEON. 
891 
ring, ^ inch thick, of a hollow cylinder 4 inches diameter, of which the outer crust had 
been removed, was crushed with 39‘06 tons per square inch ; and external rings of the 
same iron thinner than half an inch, required from 49‘2 to 51'78 tons per square inch 
to crush them. These facts show the great superiority of hollow pillars over solid ones 
of the same weight and length. 
Table VIII. (continuedj.—Casting of larger dimensions than before used. 
To ascertain whether the internal strength of larger pillars varied in the same manner 
as that of smaller ones, a cylindrical casting was made 5 inches diameter and 16 inches 
long. It was cast vertically, from Blaenavon iron. Through the axis of this cylinder, 
a slab, 16 inches long, 6 inches broad, and about I inch thick, was taken. Across the 
middle of this slab five cylinders, 1^ inch long and f inch diameter, were obtained at 
equal distances from each other, the middle one being in the centre, and the outer ones 
as near as possible to the sides. Three other small cylinders of the same size were also 
obtained, the positions of which were as in the figure. 
TOP 
Mark on 
Cylinder. 
Diameter of 
Cylinder. 
Crushing weight 
of Cylinder. 
Crushing weight 
per square inch. 
A4 
inch. 
•749 
lbs. 
27749 
lbs. 
629791 
Mean. 
65739 
B4 
•748 
30101 
68500 J 
A2 
•750 
27749 
62811 
> 62444 
B2 
•748 
27279 
62078 
A 
•748 
27749 
631471 
. 64218 
B 
•748 
28690 
65289 
A1 
•748 
28690 
65289 
A3 
•748 
29160 
66358 
Comparing the results of the experiments above, it appears that the external part of 
the casting was somewhat stronger than the internal. But the variation was only from 
62 to 66, and therefore much less than was obtained from the smaller masses. 
