142 
Gun D was cast from the air furnace in the usual way, 
under a pressure of 17 feet 6 inches of head. 
Gun E was cast from iron remelted once, and then run 
into mould, under 17 feet 6 inches head of metal. 
These guns having been bored and turned, were conveyed 
to Woolwich Marshes, and subjected to proof by firing, 
beginning with the usual proof charges, with a gradually 
increasing quantity of powder and weight of shot, until the 
gun burst. The result of these proofs is exhibited in the 
following table : — 
Gun. 
Number of 
Bounds Fired. 
Total Quantity 
of Powder used, 
in lbs. 
Total Weight 
of Shot Fired, 
in lbs. 
Total Number 
of Wads 
used. 
A 
33 
364 
3120 
91 
B 
32 
350 
2952 
90 
C 
17 
150 
1152 
43 
D 
31 
336 
2784 
89 
33 
364 
3120 
91 
From this table it will be seen that, whilst the gun cast 
with desulphurized coke from the cupola, exhibited com- 
paratively a great inferiority.* The guns E and A, one of 
which had been cast in the ordinary way, and the other with 
remelted iron, under pressure, exhibited very high powers 
of resistance. The results thus obtained were further con- 
firmed by experiments upon the tenacity and density which 
gave the following mean results : — 
Gun. Density. 
per sq. m. 
A 7.2105 28,516. 
B 7.2325 27,219. 
C 7.0863 18,101. 
D 7.2032 25,954. 
E 7.2441 28,516. 
* Considerable want of uniformity is observable in iron melted in the cupola, 
unless retained for some time in a state of ebullition at a high temperature. This 
will account for the comparative weakness of the gun C, which, under different 
treatment, would have been greatly improved by the use of desulphurized coke, 
as was found to be tlie case in former experiments. 
