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ARMOURED DEFENCES. 
The question of strengthening land fronts by means of a partial 
use of armour, is one that deserves great consideration, and, for my 
part, I see no reason why an inland fortress should not be rendered 
practically impregnable, by the judicious use of iron or steel, at no 
very great additional expense; but I should be attempting too much 
if I were to introduce these topics into this paper. 
In any case, the formation of an efficient embrasure in a very thick 
parapet involves great difficulties; but in a work exposed to the fire 
of heavy ships' guns, the strengthening, which becomes necessary in 
the neighbourhood of the embrasure, involves a treatment which alters 
the whole character of the work. The main reason however why the 
necessary strength cannot be gained in coast batteries by multiplying 
the thickness of the parapets, is that in the great majority of these 
works the character of the site practically precludes it. For instance, 
in the case of a fort at sea, it would be obviously out of the question 
to bring up foundations for an earthwork, or for a work having very 
thick parapets of other materials; and this difficulty holds good, with 
a difference only of degree, in most of the sites selected for our coast 
defence works. 
It will be observed, even from what has been already said, that in this 
paper I am going to deal only with works adapted to guns which fire 
through embrasures, or ports as they are now called—that is to say, to 
protected guns mounted on carriages and platforms of the ordinary type. 
The general character of the works of which I shall speak, has been, 
from time to time, determined by the highest authorities, and therefore 
it becomes obviously my part, as it certainly is my wish, to avoid 
entering into any discussion as to the merits of the general system 
which has been adopted in our works, compared with any other 
methods of mounting and protecting guns in coast batteries which 
have been advocated. 
I propose, broadly, to divide the subject under three heads; that is— 
1st. To trace, briefly, the experimental stages through which the 
question of iron defences has passed. 
2nd. To give some account of the materials used in these defences.* 
and of their manufacture. 
3rd. To describe, as far as time will allow., some of tile principal 
iron works which we have set up for the defence of our 
naval arsenals and ports at home, and of our fortresses abroad* 
I.—The Experimental Stages. 
And, I may say at once that the few early experiments to which I 
shall refer possess something more than a mere historical interest, 
because in them is to be found a warrant for every step we have taken 
in working out a system of iron fortification. Every point, down to 
those of the nicest detail, has been based on experimental results. 
I am sure those officers who have watched the experiments at Shoe- 
buryness and Portsmouth, will bear me out in saying that in no subject 
that has ever been raised has mere opinion, unsupported by practical 
experience, proved so worthless as in this. 
