230 
STEEL AS APPLIED TO ARMOUR. 
Properly directed forging and rolling (its half-brother) improve the 
quality of the steel immensely, and steel for plates is always so treated, 
except in the case of the steel junction 1 of Ellis compound plates. 
This forging is much more economically and effectively performed 
now, by hydraulic presses, in the place of steam hammers. More 
economically, for the same end can be attained roughly in one-third 
the number of heats, and so the extra expense of fuel for heating is 
saved, as also all the attendant risks in re-heating : and more effec¬ 
tively, because the shock of the steam hammer is not transferred 
to the interior of a large mass, but is absorbed by the outside layers, 
while the steady pressure of the hydraulic press penetrates to the 
interior of the largest masses dealt with for armour-plates, and so does 
its good work all through. 
Steel also possesses the property, while in the fluid state, of occlud¬ 
ing or absorbing within its mass certain gases, such as nitrogen and 
oxygen. On cooling, these gases try to escape, but the outer layer of 
steel having cooled first they are imprisoned, and so press up the 
steel at the top of a casting and make unsound metal, full of blow¬ 
holes. For this reason steel ingots are cast with “ heads/’ in which 
the unsound part may be concentrated, and these heads are cut off. 
A certain amount of these gases remains in the casting, but forging 
expels most of them. It is for this reason that I think the “ compound ” 
system of Messrs. Brown, on the Ellis patent, is open to objection if for 
no other. It does not seem as if there are sufficient arrangements 
made to get this head to the steel they pour in to effect the junction 
between their hard-face plate and wrought-iron foundation—as a con¬ 
sequence, frequently, on fracture, this steel junction shows signs of un¬ 
soundness, and in such a state must be unreliable as a support to the 
front plate. In addition, is the risk of “ burning 99 either the steel of 
the face-plate or the wrought-iron of the foundation which must be 
incurred by such a process, though some recent plates of theirs, 
“ Tressiderized,” have given most excellent results, as will be noticed. 
Steel armour can be divided into two broad classes :—Armour in 
which there is a hard-face plate, supported by a softer foundation; 
and the so-called all-steel armour, in which the quality of the steel is 
the same all through. As I have said, to me it seems that success in 
the future lies in the direction of the hard face, supported by the 
softer back, but all steel recently gained a victory at Ochta, St. Peters¬ 
burg, as reported by Captain Talbot in this journal. The success of 
these plates was solely due to the general excellence of the steel of 
which they were made, and Messrs. Vickers doubtless attained this 
excellence by attention to the various points in its treatment which 
have been indicated above. As one would expect in a plate of this 
class, they were soft, and such was the official opinion. But though 
they did yield to perforation, it was in a minor degree ; and their 
superiority over their competitors was marked enough to gain for 
them the Russian order. 
Turning to the other class we find two sub-divisions. 
Plates which are made in one, and of one sort of steel all through. 
1 This is only rolled. 
