INTO THE STRENGTH OF WROUGHT-IRON PLATES. 
707 
All the beams experimented upon in the foregoing Table are shown in view and in 
section, Plate LVIII. figs. 1/ and 18. In the first experiment the beam was 7 feet 
between tlie supports, but having yielded to the first weight, 3355 lbs., laid on, it was 
subsequently cut in two, as shown in the drawings above referred to. In experi- 
ment 2, it will be observed that a frame of this form is weak, arising from the de- 
ficiency of material on the lower side of the rib formed by angle-iron, which, yielding 
to a tensile strain, becomes elongated in the act of bending, and would thus deflect 
through a considerable space before actual fracture took place. Reversing the other 
part of the beam with the broad flange downwards it carried more weight, but ulti- 
mately sunk under a load of 10,759 lbs., being in the ratio of 10 ; 7 in favour of the 
beam wdth the rib upwards. 
These experiments, when reduced to 7 feet between the supports, gave nearly the 
same proportion, viz. nearly as 34 : 24. They are however all weak, arising almost 
exclusively from want of material on the top edge of the ribs, and a due proportion in 
the construction of the beam. 
Table XVII. Experiments on Wrought-iron Beams (continued). 
Oak beams. 
Breaking 
Weight 
Weight of 
Weight of 
weight of 
No. 
Deflections 
the beam 
the beam 
square of 
Remarks. 
of 
Description and form of the beam. 
laid on 
with these 
of 7 ^eet 
of 7 feet 
exp. 
middle. 
weights. 
between 
6 inches 
of equal 
6 inches 
the sup- 
long. 
strength 
long and 
ports. 
with the 
specific 
iron one. 
gravity 900. 
lbs. 
lbs. 
lbs. 
inches. 
lbs. 
4. 
Beam differing from that in exp. 1 
3,355 
•40 
After bearing the weight 
only in being of greater strength, this 
4,711 
•62 
7399 lbs. a short time the 
beam being formed of two 3-inch angle- 
5,383 
•82 
beam became cracked at a 
irons, riveted as before to a plate a 
5,719 
•98 
rivet-hole and sunk. From 
J-inch thick. Distance between the 
6,055 
M2 
the experiments of Buf- 
supports 7 feet ; weight of the beam 
6,391 
1-30 
FON upon green oak, the 
7 feet 6 inches long, 167i lbs. ; ver- 
6,727 
1-87 
side of a square beam of 
tical rib downwards 
1-92 
equal strength would he 
7,063 
2-29 
4-558 inches, and its 
7,399 
3-25 
7399 
167-5 
4-7281 
65-49 
weight 708 lbs. 
5. 
Half the beam used in exp. 4, now 
4,039 
0-85 
3 feet 9 inches long, and weighing 82^ 
7,399 
0-25 
lbs. Distance between supports 3 feet 
10,759 
0-43 
6 inches ; vertical rib downwards. 
11,431 
0-53 
12,103 
0-65 
12,439 1 
broke at 
a rivet- 
hole. 
je219 
1675 
4-462 
6. 
The other half of the beam in exp. 4, 
8,304 
012 
weighing 85 lbs. ; length 3 feet 6 inches. 
12,392 
0-24 
Distance between the supports 2 feet 
3 inches ; rib upwards | . 
16,480 
r 
0-75 
sunk, the 
] 
18,115) 
vertical 
rib being 
twisted. 
15823 
1675 
4-3653 
55-83 
The whole of the experiments herein recorded are of the same description as the 
last, with the exception of the beam being composed of thicker angle-iron, and conse- 
quently rendered much stiffer and stronger than those first experimented upon. This 
increased stiffness reversed the resisting powers of the beam, when taken at a 7-feet 
4x2 
