INTO THE STRENGTH OF WROUGHT-IRON PLATES. 
703 
Table XIII. Experiments to determine the Resistance of Plates of Wrought Iron 
to a force tending to burst them. 
No, 
of 
exp. 
Description of plates. 
Weight 
laid on 
in lbs. 
Permanent 
indentation 
of plate. 
Remarks. 
inch. 
1. 
Plate of the best Staffordshire iron 
8,617 
•3 
Plate not cracked. 
inch thick. 
9,893 
•35 
Plate not cracked. 
11,169 
■5 
Crack on convex side 8 inches long. 
12,445 
•6 
Crack on convex side 9 inches long ; not opened on concave side. 
13,789 
•7 
Hole through the plate about 1^ inch long, and ^ inch wide. 
2. 
Plate of the same iron and the same 
9,893 
•25 
Double crack on convex side 1 inch long. 
thickness. 
11,169 
•34 
Double crack increased. 
12,445 
•4 
13,789 
•47 
16,477 
•6 
Form of crack on convex side (a inch wide). 
17,821 
•65 
Not cracked through. 
19,769 
Cracked through. 
3. 
Plate of the same iron ^ inch thick. 
18,523 
No crack. 
21,075 
•33 
Incipient crack on convex side. 
22,787 
•45 
Crack above-mentioned 4 inches long, forming a cross. 
25,923 
•60 
Crack above, 6 inches long. 
29,059 
•75 
Crack above, a inch wide. 
32,195 
■80 
35,331 
•97 
— ' 
36,899 
110 
No crack on concave side. 
37,519 
Plate cracked through. 
4, 
Plate same as the last. 
21,219 
No crack. 
21,985 
•35 
Shght crack on convex side. 
27,708 
•47 
Form of crack on convex side. 
31,796 
•7 
Form of crack increased. 
33,431 
•75 
35,066 
•83 
Form of crack 4 inches deep. 
36,701 
•97 
Not cracked through. 
37,928 
Cracked through. 
In Plate LVIII. figs. 13 and 14, will be found representations of the fractures of 
the plates experimented upon in this Table, 
From the above we obtain the strength of plates to resist rupture from pressure 
from a blunt body, or a ball 3 inches diameter. 
lbs. Mean. 
In experiment 1, a plate one-fourth of an inch thick was burst by 13,789 
In experiment 2, a plate one-fourth of an inch thick was burst by 19,769 
In experiment 3, a plate half an inch thick was burst by . . . 37,519 
In experiment 4, a plate half an inch thick was burst by . . . 37,928 
j 16,779 
j 37,723 
Here the strengths are as the depths, a half-inch plate requiring double the weight 
to produce fracture that had previously burst the quarter of an inch plate. In the 
succeeding experiments on oak timber, the powers of resistance follow the ratio of 
the squares of the depth, so that a wrought-iron plate of only one-quarter of an inch 
thick is able to resist a force equal to that required in the rupture of a 3-inch plank. 
The experiments were made upon good English oak, of different thicknesses, and 
of the same width as the iron plates. The specimens were laid upon solid planks, 
12 inches asunder, and by the same apparatus the rounded end of the 3-inch pin was 
forced through them as follows : — 
