IMPROVEMENTS IN THE CONSTRUCTION AND MANUFACTURE OF ARMOUR PLATES
Year: 1878

page_text: LETTERS PATENT to Robert Hadfield, of Sheffield, in the County of York,
for the Invention of "IMPROVEMENTS IN THE CONSTRUCTION AND MANUFACTURE
OF ARMOUR PLATES."
Sealed the 12th July 1878, and dated the 14th January 1878.
PROVISIONAL SPECIFICATION left by the said Robert Hadfield at the Office
of the Commissioners of Patents on the 14th January 1878.
ROBERT HADFIELD, of Sheffield, in the County of York.
THE CONSTRUCTION AND MANUFACTURE OF ARMOUR PLATES."
"IMPROVEMENTS IN
Hitherto it has been customary to manufacture armour plates from iron by first
puddling the iron, and subsequently passing the same through various welding and
building up processes, thus involving enormous labour and expense. I am also
aware that several eminent firms have made trials of compound plates of steel and
iron welded together, also plates made of all steel, some of which latter have resisted
projectiles better than wrought-iron plates, but all more or less shewing the fatal
quality of singing, starring, or cracking, in consequence of the tremendous strain
set up in the plate by being struck or partly pierced by projectiles.
Now one of the objects of my improved armour plates is to remedy this singing,
cracking, or starring.
Another object is to secure great economy.
A third object is to diminish the weight of the plates as now used, at the same
time that they retain their present thickness.
My improvements in the manufacture of armour plates for ships and forts
consist in the employment of steel, wrought iron, chilled cast iron, and wood, in the
manner hereafter described.
To carry out my improvements I first cast in a very mild steel (that is to say,
steel very low in carbon) a skeleton shell or hollow armour plate open at the back,
with cross ribs running the whole length and breadth of the hollow part. I also
cast in the front of this hollow plate pockets, recesses, or indentations of any
desired depth or form, but by preference round or cup shaped at the bottom, or in
[Price Bl

page_text: the shape of an inverted cone. I then subject this hollow steel casting to an
annealing process, and 1 then proceed to make and fit the plates together, either
leaving the recesses at the back hollow, or by preference I cast in between the ribs
at the back slabs of chilled cast metal of any desired thickness, but so arranged as
to be always level or flush with the rabbet previously made to receive a plate of
good tough wrought iron of the quality now used for armour plates, or a suitable
casting made of steel may be inserted in lieu of such wrought-iron plates. I thus
have tough wrought iron or steel at the back, chilled cast metal in the middle, and
steel casting all round the edges and front. I next proceed to force into the before-
mentioned pockets, recesses, or indentations blocks of any suitable description of
wood, made of any convenient size and shape so as to perfectly fit the cavities of
such pockets. The plate then presents the appearance of a solid plate, but any
projectile on striking this plate is compelled to diverge into one or other of these
wood-filled pockets, the effect of which will be to deaden and to absorb a great deal
of the force or energy of the blow. If penetration takes place through the solid
bottom of the pocket the projectile is immediately met by the chilled metal, which
will effectually bar its further progress by breaking up the projectile.
I do not confine myself to any particular number of ribs or compartments at the
back of the plate, as that is determined by the size of the plate; nor do I confine
myself to any particular dimensions as regards the before-mentioned pockets,
indentations, or recesses, either in diameter, or depth, or otherwise.
The bolts for holding the plate to its place must pass through both steel metal
and wrought iron.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Robert Hadfield in the Great Seal Patent Office on the 12th July
1878.
ROBERT HADFIELD, of Sheffield, in the County of York.
THE CONSTRUCTION AND MANUFACTURE OF ARMOUR PLATES."
"IMPROVEMENTS IN
Hitherto it has been customary to manufacture armour plates from iron by first
puddling the iron, and subsequently passing the same through various welding and
building up processes, thus involving enormous labour and expense, in order to
avoid which I am aware that several experiments have been made with composite
armour plates manufactured of steel and iron welded together, and also with plates
manufactured entirely of steel, some of which latter have resisted projectiles better
than wrought-iron plates, but all such plates have more or less shewn the fatal
quality of singing, starring, or cracking, in consequence of the tremendous strain set
up in the plate when struck or partly pierced by projectiles.
Now my improvements in the manufacture of armour plates relate,―
Firstly. To remedying such singing, cracking, or starring.
Secondly. To effecting a great economy in the cost of manufacture.
And, Thirdly. To diminishing the weight of the plates as now manufactured, at
the same time that they retain their present thickness, and possess increased powers
of resistance.
To effect these various results I employ in the manufacture of armour plates for
ships and forts a combination of steel, wrought iron, chilled cast metal, and wood,
in the manner hereafter described and illustrated in the accompanying Drawings;
Figure 1 whereof is a front view of one of my improved armour plates, shewing
the pockets or recesses hereafter described; Figure 2 is a view in vertical section of
the same; and Figure 3 is a view of the back thereof before being filled up.
Now in order to carry out my improvements I first cast in very mild steel (that
is to say, steel very low in carbon) a skeleton shell or hollow armour plate open at
the back, and having cross ribs running the entire length and breadth of the hollow
part. I also cast in the front of this hollow plate pockets, recesses, or indentations
of any desired form and depth, but preferably either round or cup shaped at the
bottom, or in the shape of an inverted cone, as shewn at Figure 1 of the accom-
panying Drawings. I then (after subjecting such hollow steel casting to an,
annealing process, similar to that practised by me in the manufacturing of other
steel castings) proceed to make and fit the plates together, and to properly secure
them by suitable bolts and nuts or otherwise, and I then cast in between the ribs
at the back slabs of hard steel or chilled or other cast metal of any desired
thickness, so arranged as to be always level or flush with the rabbet previously
made to receive a plate of good tough wrought iron of the quality now used for
armour plates. I thus have tough wrought iron or steel at the back, chilled cast
metal or steel in the middle, and steel casting all round the edges and front of the
plate. I next proceed to force into the before-mentioned pockets, recesses, or
indentations by any suitable means blocks made of any suitable description of wood,
and of any convenient size and shape, so as to perfectly and tightly fit into the
cavities of such pockets or recesses. The plate then presents the appearance of a
solid plate, but on any projectile striking my improved armour plate, such projectile
is compelled to diverge into one or other of the wood filled pockets or recesses, the
effect of which divergence is to deaden and absorb a great deal of the force or
energy of the blow, and should penetration take place through the solid bottom of
the pocket, the projectile is immediately met by the chilled cast metal, which will
effectually bar its further progress by breaking up the projectile.
I do not confine myself to any particular number of ribs or compartments at the
back of the plate, as such number is determined by the size of the plate itself;
neither do I confine myself to any particular dimensions as regards the before-
mentioned pockets, indentations, or recesses, either in diameter, depth, or otherwise,

page_text: The bolts for holding the plate in position pass through the steel metal and
wrought iron, and are properly secured in any convenient manner.
My improved armour plates are equally applicable to land forts and other
defences on land as to vessels of war.
The following are the principle advantages of my improved method of manu-
facturing armour plates, viz.,-
Firstly. The effecting an enormous economy in the cost of the manufacture of
armour plates as compared with the existing methods at present practised, owing to
the large amount of chilled or other cast metal which may be placed in the skeleton
shell, as before described, in substitution for costly wrought iron and steel as at
present used.
Secondly. The non-liability of armour plates manufactured upon my improved
principles to singing, starring, or cracking.
Thirdly. The effectually localizing any injury inflicted on the armour plate by
the blow of a projectile, owing to the capacity of the outer skin thereof to receive
a large amount of injury without transmitting the effect of the same to the back of
the plate, by reason of each part being independent of the other, and not connected
thereto by welding, at the same time that the inner parts are securely held in
position by the steel shell or case of the armour plate, as before described.
Fourthly. By my improved method of casting skeleton hollow plates with pockets
or recesses therein, and also of filling such pockets or recesses with wooden plugs,
the weight of the armour plate is considerably reduced, at the same time that its
defensive properties are increased, and by so doing when my improved armour plates
are applied to a vessel greater buoyancy is imparted to the same, thus materially
increasing her speed, as also the facility of manoeuvring her, either when in action,
or in stress of weather, or otherwise.
Having thus particularly described and ascertained the nature of the said
Invention, and the manner of carrying the same into effect, I would have it under-
stood that I claim the manufacture and use of an improved composite armour plate
or plates suitable for naval and military defensive purposes, consisting of a combi-
nation of steel, wrought iron, chilled cast metal, and wood, all of suitable quality,
substantially in the manner and for the purposes herein-before set forth and
described.
In witness whereof, I, the said Robert Hadfield, have hereunto set my hand
and seal, this Eleventh day of July, in the year of our Lord One thousand
eight hundred and seventy-eight.