INTO THE STRENGTH OF WROUGHT-IRON PLATES. 
709 
Table XIX. Experiments on Wrought-iron Beams (continued). 
Breaking 
weight of 
the beam 
of 7 feet 
between 
the sup- 
ports. 
Oak beams. 
No. 
of 
exp. 
Description and form of the beam. 
Weight 
laid on 
middle. 
Deflections 
with these 
weights. 
Weight of 
the beam 
of 7 feet 
6 inches 
long. 
Side of 
square of 
oak beams 
of equal 
strength 
with the 
iron one. 
Weight of 
such beams 
of 7 feet 
6 inches 
long and 
specific 
gravity QOO. 
Remarks. 
11. 
Beam of ■wrought iron, formed of 
two bars (nearly equal), whose section 
is riveted together ; length of the heam 
lbs. 
4,195 
7,465 
10,735 
0-75 
0148 
0-22 
lbs. 
lbs. 
inches. 
lbs. 
4 feet 2 inches ; its weight 44 lbs. 5 oz. 
Distance between the supports 4 feet. 
Dimensions of section. 
10,735 
laid on 
again. 
Afterbearingthe weight 
10,735 lbs., the beam had 
taken a set =-06. Pieces 
AB =2-86 inches. 
Mean thickness of 
AB= ‘33 inch. [M 
EF = 3'70 inches. ^ 
E 
14,005 
0-24 
broke 
8336 
79-76 
4-9199 
70-91 
of wood were driven tightly 
in between the ribs AB, 
CD, at each side of the 
beam in t7ie middle, to pre- 
vent the load laid on it there 
from deranging its form. 
The beam broke by the 
bottom rib being torn 
asunder, preceded by one 
of the bars cracking at a 
rivet-hole. 
The above is probably the strongest form of beam, if duly proportioned, by adapt- 
ing the material to a balance of the two opposing forces of extension and compres- 
sion. 
Table XX. Experiments on Wrought-iron Beams (continued). 
No. 
of 
exp. 
Description and form of the beam. 
Weight 
laid on 
middle. 
Deflections 
with these 
weights . 
Breaking 
weight of 
the beam 
of 7 feet 
between 
the sup- 
ports. 
Weight of 
the beam 
of 7 feet 
6 inches 
long. 
Oak beams. 
Remarks. 
Side of 
square of 
oak beams 
of equal 
strength 
with the 
iron one. 
W''eight of 
such beams 
of 7 feet 
6 inches 
long and 
specific 
gravity 900. 
12. 
Beam of wrought iron comp 
an uniform vertical rib (7 inch 
and 7 feet 6 inches long) with two 
angle-irons riveted to both tc 
bottom of the rib ; rivets 4 
asunder ; weight of beam 16 
Distance between the supports 
Dimensions of section. 
CD = 7 inches. ^ 
AB =4-5 inches. 
EF = 4-5 inches. 
Mean thickness of 
AB = '28 inch. 
EF=-30inch. 
Plate GII = -25. 
1 
Dsed of 
5S deep 
2-inch 
)p and 
inches 
I J- lbs. 
7 feet. 
i 
f 
lbs. 
4,216 
8,304 
16,480 
18,667 
22,027 
in five 
minutes 
24,379 
•10 
•18 
•25 
•36 
•52 
} ■“ 
sunk 
lbs. 
24,379 
lbs. 
161i 
inches. 
7*0358 
lbs. 
14503 
With the weight 24,379 
lbs. the top ribs of the 
beam became twisted. 
13. 
Same beam rendered straight and 
uniform ; experiment 12 repeated. 
16,115 
18,355 
19,475 
20,595 
21,715 
•29 
-36 
-42 
•51 
sunk 
21,715 
164 
6-7695 
134-26 
The beam was heated 
by the smiths, and when 
reduced to its original form , 
it was allowed to cool gra- 
dually. 
With 21,715 lbs. it be- 
came bent, towards the 
wall, in adirection in which 
it was slightly drawn by 
the lever ; i-ibs not twisted 
as before. It bore the 
weight a minute or two 
before giving way. 
