INTO THE STRENGTH OF WROUGHT -I RON PLATES. 
681 
The results obtained from the Low Moor plates in the preceding Tables give fair 
indications of their strength. It will be observed, on comparing the mean of the 
breaking weights in this case with the experiments of Brown and Telford, that there 
is a very slight difference between the strength of plates and bar iron. 
Taking the results of Captain Brown, we have in eight experiments on Swedish, 
Welsh and Russian iron, 25 tons as a mean of the breaking weight when reduced to 
an inch square. 
In Mr. Telford’s experiments on Swedish, Welsh, Staffordshire and faggoted iron, 
the mean breaking weight obtained from nine different bars was 29^ tons to the 
square inch. The comparison will then be — 
Captain Brown’s experiments, 25 tons to the square inch . . • .q jyiean 
Minord and Desames’ experiments, 25 tons to the square inch . . l26’4l tons. 
Mr. Telford’s experiments, 29x tons to the square inch . . . . J 
Yorkshire plates’ experiments, 24^ tons to the square inch. 
Making the strength of plates to that of bars as 24’5 : 26'4, being a comparatively 
small difference in their respective powers to resist a tensile force. 
Table III. Strength of Plates. — Derbyshire Iron. 
No. 
of 
exp. 
Description of plate 
and dimensions in the 
middle. 
Weight 
laid on in 
lbs. 
Reduced dimensions in 
middle of plate thrcfugh 
weights laid on. 
Breaking 
weight 
in lbs. 
Mean breaking weight 
in lbs. 
Remarks. 
9. 
10 . 
Drawn in the di- 
rection of the fibre 
Area of section 
2-00x'28in. 
Form of specimen the same as shown 
in Table I. fig. 2, 
X 
2 00x-29in. j 
21,219 
28,66; 
21,219 
22,789 
26,707 
Stretched. 
2-00 X -27 
Sinking. 
Sinking. 
2-15 X -27 
28,667 
26,707 
O O O 
ooo 
oo o 
ooo 
ooo 
ooo 
27,687, or21'68 tonsper 
square inch. 
There was a stripe resembling steel 
across the fracture near one side. 
11 . 
12 . 
Plates drawn 
across the fibre. 
Area of section 
2’00x-28 = -56in. 
200 X -28 = -56 in. 
22,395 
23,179 
24,747 
Stretching. 
Thickness '27 
2'00x-28 
23,179 
24,747 
23,963, or 18-65 tons per 
square inch. 
In the broken surface there seemed to 
be a stratum of steel, the rest was lami- 
nated hut imperfectly. 
Short streaks of steel in fractured sur- 
face. 
If we compare the results in the Derbyshire plates with those in the preceding 
Tables, we have in the mean of four experiments a ratio of 20T65 : 24'850, or 5 to 6 
nearly. 
Again, by comparing the same plates with the mean strength of bars reduced to 
an inch square, the difference will be as 20 to 26, being an excess of 6 tons in favour 
of the bars. 
4 s 
MDCCCL. 
