828 
ARMOURED DEFENCES. 
But it was taken up in Prussia, and in 1869 a chilled cast-iron 
casemate front, egg-shaped, (thickness of metal about the port, 27-ins.) 
underwent a considerable trial, at Tegel, with 72-prs. and 96-prs., and 
it stood fairly well. The indents were very slight, but the material, 
as usual, was extremely brittle, and, to adopt the expressive language 
of a report quoted in the professional papers of the Corps of Engineers, 
U.S. Army, it was “ pretty well cracked up.” 
The next trial of chilled cast-iron armour was at Magdeburg, in 1874, 
against a very massive rounded target made by Griison, and, although 
both from the form of the structure and the hardness of the material, 
individual shot were very effectually turned off it, yet repeated blows 
caused serious injury. 
Still, the Germans and Belgians have adopted this mode of con¬ 
struction for both shields and turrets—especially for a number of 
21 cm and 28 cm breech-loading muzzle-pivoting guns for the defence of 
the mouths of rivers. Some of the other European powers also are using 
it, to a greater or less extent, for both inland and coast fortresses. 
The chief advantage of this material is that it can be made of any 
shape, and therefore rounded and sloping surfaces can be presented to 
the shot; and it affords also a certain facility for varying at will the 
thickness of the metal in the different parts of a wall. 
The problem is whether for a given sum of money greater efficiency 
and more complete protection can be obtained by means of cast-iron 
than with wrought-iron, and nothing but a fair trial between two 
structures under heavy fire can, in my opinion, solve this. 
I must not omit altogether to mention that a chilled cast-iron block 
was used last year in the Meppen trials, but I am afraid it did not 
afford much reliable information. 
It must be borne in mind that the guns protected by cast-iron walls 
must be muzzle-pivoted, and also almost of necessity breech-loaded. 
Steel and 
compound 
armour 
again tried. 
Next, as to experiments with steel, and compound steel and iron, 
armour. 
Even as early as in 1859 armour-plates of mild steel and steely iron, 
and iron and steel combined, and various kinds of steel plates 
tempered in oil and water had been tried, and all failed in a greater or 
less degree when they came to stand the test of shot blows. 
I have already said that when the employment of steel for armour 
was taken up again in this country in 1867, the steel was beaten by 
simple wrought-iron plates. 
And so the matter of steel armour rested until the Italians in 1876 
boldly re-opened the question by setting up two armour plates (made 
by M. Schneider, of Creusot) of soft forged steel 21 f ins. thick, for 
trial at Spezia. The plates were about 11 ft. long and 4 ft. 7 ins. wide, 
and they were backed with massive oak covering a strong iron skin 
well supported in rear. 
For comparison with these, three iron plates of nearly the same 
dimensions as the steel plates, and similarly supported, were tried at 
the same time, as well as two plate-upon-plate targets, each consisting 
of iron plates 11 *8 ins. and 9*8 ins. thick, with 12 ins. of wood between 
