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NATORE 
405 
THURSDAY, MARCH 1, 1883 
RECENT ARMOUR-PLATE EXPERIMENTS 
T the conclusion of their labours the “Iron Plate 
Committee” reported, in 1865, that the best material 
for the armour of war-ships was wrought iron of the 
softest and toughest nature. Steel, or steely iron, or 
combinations of iron and steel were all pronounced un- 
suitable for the purpose, after a long course of careful 
experiments. Accepting this verdict the designers of 
armoured ships continued to specify for soft iron armour, 
the makers of guns and projectiles aimed at the perfora- 
tion of this kind of armour, and the manufacturers sought 
to secure the desired qualities of softness and toughness 
in the thicker and heavier plates which they were con- 
stantly being called upon to produce. All the armoured 
ships built from 1860 to 1876 were ‘‘ironclads,’’ and in 
that time the thicknesses of armour plates carried on the 
sides or batteries of completed ships had advanced from 
4% inches to 14 inches, while the weights had risen from 
4 or 5 tons to 20 or 25 tons. Greater aggregate thick- 
nesses of iron had been arranged for prior to 1876. For 
example, the /7/flexzble had been designed to carry 24 
inches of iron on her sides, but this was in two layers of 
12-inch plates. The adoption of the so-called “‘ sandwich- 
fashion ’’ of armour plating was based upon experiments 
made at Shoeburyness, and it had certain advantages of 
a constructive character ; it also enabled broader and 
longer plates to be produced within the fixed limits of 
weights with which the manufacturers could deal, and 
enabled them to insure excellence of quality which might 
not have been so certain of attainment in plates of 20 
inches or upwards in thickness. 
While the two great Sheffield firms and their rivals in 
France were thus developing the manufacture of iron 
armour plating, the Creusot Company, of which M. 
Schneider was the head, were attempting to reverse the 
verdict against steel armour, and to produce specimens 
which could hold their own against the best iron armour 
of equal thickness. The Italian Admiralty brought the 
claims of the rival materials to the test of experiment at 
Spezia in October, 1876. In order to decide on the kind 
of armour to be used on the Duzlio and Dandolo, speci- 
men targets were erected and a series of firing trials made 
against them on a scale of unprecedented magnitude. A 
gun weighing 100 tons, manufactured at Elswick, was 
brought to bear upon targets protected by iron or steel 
plates 22 inches thick, backed by great masses of timber 
and strong supports. Other guns of considerable weight 
and power were also used, but their performances were 
overshadowed by those of the monster weapon. The 
results of these trials may be briefly summarised. Against 
the 10-inch and 11-inch guns the 22-inch iron plates had 
a decided advantage over the steel plate of equal thick- 
ness. The penetration was somewhat greater in the iron 
plates, but the steel plate cracked badly. On the other 
hand, when the Ioo-ton gun was brought against the 
targets the iron plates and their backings were completely 
perforated as well as broken up: whereas the steel plate, 
-although smashed to pieces, prevented the shot from 
passing through the backing. 
VOL. XXVIIL.—NOo. 696 
Various opinions were 
i 
formed as to the deductions which should be made from 
these trials. On the one side it was urged that as steel 
plates of great thickness could be gradually cracked and 
destroyed by guns incapable of perforating them, steel 
ought not to be used instead of iron, which could be 
battered by a great number of projectiles from such guns, 
and be neither perforated nor cracked. On the other 
side it was maintained that there was small probability 
of any single armour plate on a ship’s side being struck 
repeatedly in action ; and consequently that the material 
should be preferred which could best resist perforation by 
a single projectile from the most powerful gun, even if 
the resistance to perforation involved the partial destruc- 
tion of the plate struck. The Italian authorities adopted 
the latter view, and the Duz/io and Dandolo have steel 
armour, being the first ships protected in that manner. 
Although these steel armour plates were made in 
France, the French authorities did not follow the Italian 
lead and abandon iron armour, Nor was a similar course 
followed in England. Change was seen to be inevitable, 
but it was endeavoured to make the change in a direction 
which should combine the high resistance to perforation 
of steel with the power to resist cracking and disintegra- 
tion possessed by tough rolled iron. To Messrs. Cam- 
mell and Co. of Sheffield belongs the honour of taking 
the lead in this direction; Messrs. Brown speedily fol- 
lowed, and the Admiralty gave substantial assistance in 
the conduct of the necessary experiments. In the earlier 
stages many failures and disappointments were expe- 
rienced ; but eventually better results were obtained, and 
‘€steel-faced armour’’ became recognised as the substi- 
tute for iron on English war-ships. Steel-faced armour, 
as the name implies, consists of a rolled iron back-plate, 
on the face of which is welded a layer of steel. The 
hard steel face resists perforation, and breaks up or 
deforms the projectiles, while the intimate union of the 
tough iron back with the hard steel face prevents the 
serious cracking which occurs in steel alone. Curiously 
enough the idea was not merely an old one, but a small 
plate made on this principle, 44 inches thick, had been 
fired at in 1863. This early steel-faced plate was broken 
into two pieces at the first shot of a light gun, and was 
condemned by the Iron Plate Committee. Fourteen 
years later plates of a similar character, so far as the 
combination of steel and iron is concerned, but of im- 
proved manufacture, were ‘successfully resisting three 
shots, either of which would have perforated an iron 
plate of equal thickness. 
The first steel-faced plates were used on the /7/levzdle’s 
turrets: they were 9 inches thick, worked ‘ sandwich- 
fashion” outside 7-inch iron armour. It was part of the 
contract that a test-piece from each steel-faced plate 
should be fired at with a 12-ton gun, and should receive 
three shots without being broken up or perforated. This 
was considered to be a very severe test at the time, and 
undoubtedly was so when the novel conditions of the 
manufacture are considered. It was successfully met, 
however, and from that time onwards the manufacture 
has steadily improved. As an indication of what has 
been done, it may be stated that steel-faced plates 11 
inches thick have received no less than eight shots from 
the 12-ton and 18-ton muzzle-loading guns, with battering 
charges and at Io yards’ range, without perforation or 
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