320 
ARMOURED DEFENCES. 
Chilled 
cast-iron 
projectiles 
adopted. 
about 1320 f.s. There was also a 7-in. Whitworth (130-pr.) and a large 
13-in. smooth-bore Horsfall gun. But shortly afterwards a 23-ton gun 
of 13’3-in. calibre, capable of piercing a ship’s side, stronger than that 
of the “ Warrior,” at 2 miles range with a shot of 600 lbs., called for a 
corresponding advance in the strength of armoured structures. 
Consequently H.M.S. “ Hercules” was protected with 9-in. armour at 
her water-line; and a target representing her at this part, with a very 
massive backing of teak and iron stringers, ribs, and skin, afforded 
effective resistance to the gun I have referred to at 700 yds. range, 
and would have done so at much shorter ranges. This trial showed 
the advantage of giving depth or thickness to shot-resisting structures. 
A method of holding on armour plates by continuous irons turned 
over their edges instead of by bolts was also tried, but there were 
objections to it. 
Turning again more particularly to the protection of land works, 
the following experience was gained about this time—that is, in 1865. 
Two complete masonry casemates with ports in iron shields were 
built at Shoeburyness. The masonry was 14 ft. thick, consisting, 
generally, of a face of 6 to 8 ft. of stone with brickwork behind it, and 
the side walls and vaulting of the casemates were of brick. The shield 
of one was a compound structure 12 ft. long, 8 ft. high, and, altogether, 
21 ins. thick (including 7 ins. of wood) ; that of the other was made 
out of a solid rolled iron plate, 7 ft. high, 6 ft. wide, and 13^ ins. thick. 
After the mounting, working, and firing of a 23-ton and a 12-ton gun 
in the casemates, as well as on the roofs, had proved the work to be 
suitable in arrangement for such guns, the front of the work was 
attacked by a battery of 7-in., 8-in., 9'22-in., and 10-in. guns, at 
ranges of 600 and 1000 yds., firing steel and cast-iron shot, some with 
hemispherical, and some with elliptical heads. 
The general result of this trial was that after 33 hits the work began 
to become untenable, after 54 hits its fire would have been virtually 
silenced, and after 86 hits, of which 22 were on iron, the masonry front 
was destroyed, but the shields still afforded a fair amount of protection. 
The aggregate of all the blows delivered came to 200,000 ft. tons, of 
which 52,000 were on iron. 
The issue of this experiment was of the utmost importance to the 
service, because on it were based the decisions (1) that our most advanced 
and important sea forts should be protected by walls consisting wholly of 
iron, and (2) that for other coast batteries masonry might be used, but 
that every gun casemate of these should have a shield affording pro¬ 
tection against fire equal, at least , to that of its own gun. 
Amongst many other trials that took place about this time were those 
which brought out the excellent qualities of chilled cast-iron for 
battering projectiles, as proposed by Capt. (now Sir W.) Palliser, and 
also the advantages of the pointed (ogival) over the blunt (hemispherical) 
head. For these experiments iron armour placed both directly and 
obliquely to the line of fire was used; chilled iron, in consequence of 
these results, almost entirely superseded steel for battering projectiles, 
for a time at least. As this question, however, has been recently re¬ 
opened it will be briefly noticed later on in this paper. 
