IMPROVEMENTS IN THE MANU- FACTURE OF ARMOUR FOR SHIPS AND FORTS
Year: 1877

page_text: LETTERS PATENT to Sir Joseph Whitworth, Baronet, of Manchester, in the
County of Lancaster, for the Invention of "IMPROVEMENTS IN THE MANU-
FACTURE OF ARMOUR FOR SHIPS AND FORTS."
Sealed the 26th June 1877, and dated the 4th May 1877.
PROVISIONAL SPECIFICATION left by the said Sir Joseph Whitworth at
the Office of the Commissioners of Patents on the 4th May 1877.
Sir JOSEPH WHITWORTH, Baronet, of Manchester, in the County of Lancaster.
* IMPROVEMENTS IN THE MANUFACTURE OF ARMOUR FOR SHIPS AND FORTS."
For this purpose I employ a material of great strength and ductility capable of
being hardened. I fashion this material in such manner as to localise the action of
the projectile when striking the armour, and also to facilitate the hardening of the
material by means of oil. I use fluid compressed steel, which I reduce to the section
desired; perforations are made in the armour at short intervals.
In some cases I reduce the diameter of the perforations at the back of the armour.
The perforations allow of the metal when struck being more readily displaced
laterally on the front face of the armour, which thereby saves the back part from
injury.
In some cases I insert hard plugs into the perforations.
Instead of forming armour of large plates I sometimes build it up in sections of
hexagonal or other suitable shapes of a material which admits of being made very
hard, and I employ screw plugs to prevent the displacement of the sections in the
direction of the impact of the projectile.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Sir Joseph Whitworth in the Great Seal Patent Office on the 3rd
November 1877.
Sir JOSEPH WHITWORTH, Baronet, of Manchester, in the County of Lancaster.
"IMPROVEMENTS IN THE MANUFACTURE OF ARMOUR FOR SHIPS AND FORTS."

page_text: My improvements in the manufacture of armour for ships and forts relate to the
employment of steel in the manner herein-after described and illustrated in the
accompanying Drawings, the steel being so treated and applied as to cause a
projectile striking the armour to be wholly or partially destroyed, whilst com-
paratively small injury is done to the armour.
The steel which employ to insure the essential condition of soundness is
"Whitworth's fluid press steel" made in the manner described in the Specifications
of former Patents granted to me, viz., that dated the 24th November 1865, No. 3018,
that dated the 29th September 1866, No. 2522, and that dated the 7th September
1874, No. 3062.
To localize the effect of a projectile when striking an armour plate, I perforate it
with holes of suitable size and at the requisite distance apart, the tendency of the
plate to crack is thereby diminished and the spreading of cracks is prevented.
The perforations afford facility for applying the oil hardening process.
In cases where weight is not a great object and where it might not be desirable to
use a costly description of armour, I make use of armour plates perforated with
holes, which are left unfilled.
In cases where weight is more to be considered than cost, I insert hardened screw
plugs into the perforations, these screw plugs being made of considerably stronger
metal than the body of the plate. It is desirable that the perforations should be BO
close that the projectile can only slightly penetrate without coming in contact with
one or more of the plugs. This arrangement enables me to obtain the requisite
strength with less thickness of armour.
In cases where reduction of weight is of primary importance I use slabs of hexagon
or other suitable shape. The dimensions should be such that the area of resistance
is three or four times the area of the projectile; in this form the entire face of the
armour is of metal of high textile strength, and the result is that the thickness of the
armour may be proportionally decreased. I support these slabs by a plate at the
back
In some cases when the plate at the back requires to be thin I connect the
hexagon slabs to one another by means of screws, one being inserted at each corner
of the hexagon. It will thus be seen that I so form the armour that I am able to
combine steel of various degrees of strength, having a tensile strength varying from
40 to 100 tons per square inch, the larger masses being of the lower strength, and
the cylindrical plugs and hexagonal slabs of the higher strength.
When neither the screw plugs nor the hexagons are used and it is considered
desirable to have a harder face to the perforated armour, I subject the plate to the
well-known process of cementation for many days, surrounded by charcoal, until the
metal is carbonized to the depth desired.
In order that my Invention may be most fully understood and readily carried
into effect, I will proceed to describe the Drawings hereunto annexed.

page_text: Third. The manufacture of steel armour with perforations, and with hard steel
plugs inserted into the perforations, substantially as described.
Fourth. The manufacture of steel armour by combining hexagonal or other
sections of hardened steel with a plate by means of screw plugs, substantially as
described.
Fifth. The manufacture of armour for ships and forts, substantially as described
and represented respectively in the annexed Drawings.
In witness whereof, I, the said Sir Joseph Whitworth, have hereunto set my
hand and seal, this Second day of November, in the year of our Lord
One thousand eight hundred and seventy-seven.
JOSEPH WHITWORTH. (LS.)