IMPROVEMENTS IN SHELLS
Year: 1862

page_text: LETTERS PATENT to Joseph Whitworth, of Manchester, in the County of
Lancaster, for the Invention of "IMPROVEMENTS IN SHELLS."
PROVISIONAL SPECIFICATION left by the said Joseph Whitworth at the
Office of the Commissioners of Patents, with his Petition, on the 2nd
June 1862.
I, JOSEPH WHITWORTH, of Manchester, in the County of Lancaster, do
hereby declare the nature of the Invention for "IMPROVEMENTS IN SHELLS,"
to be as follows:-
These improvements relate to shells intended to be fired through metal
plates such as may be used as armour for ships, forts, or other defences. The
shells are made of metal properly hardened. They are solid for a sufficient
length in front of the internal cavity to give the requisite strength for pene-
tration. The fuse usually employed for igniting the bursting charge is dispensed
with, as the heat generated by the impact of the shell is sufficient to ignite
the charge. To prevent the heat generated by impact from acting prema-
turely and to regulate the time of ignition the bursting charge is surrounded
by a proper thickness of flannel or other material which is a non-conductor of
heat.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said Joseph Whitworth in the Great Seal Patent Office on
the 2nd December 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
WHITWORTH, of Manchester, in the County of Lancaster, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Second day of June, in the year of our Lord
One thousand eight hundred and sixty-two, in the twenty-fifth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Joseph Whitworth, Her special licence that I, the said Joseph
Whitworth, my executors, administrators, and assigns, or such others as J,
the said Joseph Whitworth, my executors, administrators, and assigns, should
at any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "IMPROVE-
MENTS IN SHELLS," upon the condition (amongst others) that I, the said Joseph
Whitworth, my executors or administrators, by an instrument in writing under
my, or their, or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the same
was to be performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date of
the said Letters Patent.
NOW KNOW YE, that I, the said Joseph Whitworth, do hereby declare the
nature of the said Invention, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement,
thereof, that is to say :-
These improvements relate to shells intended to be fired through metal
plates such as may be used as armour for ships, forts, or other defences.
Shells as heretofore constructed have not been fired in an entire condition
through armour plates of any considerable thickness, such as the thick plates
of iron now commonly applied to ships to protect them from injury from
projectiles; they have always broken up upon impact, and when used as live
shells the bursting charge has ignited prematurely. It has therefore been
supposed that comparatively much thinner armour plates would suffice to
exclude shells than would be required to keep out solid shot propelled with an
equal charge of powder. Now it has been found that one cause of the ineffi
ciency of shells heretofore employed against armour plates has been that the

page_text: concussion on a shell striking armour plates of any considerable thickness, and
with velocity sufficient to penetrate it, generates so much heat as to explode
the bursting charge in the shell, thus fracturing it before it has had time to
pass through the armour plating. Another cause of the inefficiency of shells
heretofore employed against armour plates has been that the shells have been
so weak that the force of the blow.has been sufficient to fracture them
mechanically; this weakness has arisen usually from the materials of which
the shells have been formed being soft or brittle, or both, and in many cases
also from the form given to the shell. It is essential in the construction of
shells capable of being used efficiently against armour plates that. the fracture
of the shell from the causes above mentioned should be prevented.
According to my Invention shells are made of metal properly hardened.
They are solid for a sufficient length in front of the internal cavity to give the
requisite strength for penetration. The fuse usually employed for igniting the
bursting charge is dispensed with, as the heat generated by the impact of the
shell is sufficient to ignite the charge. To prevent the heat generated by
impact from acting prematurely, and to regulate the time of ignition, the
bursting charge is surrounded by a proper thickness of flannel or other
material which is a non-conductor of heat.
The shells are conveniently constructed of the form shewn in Figure 1 of
the annexed Drawing, this Figure being a side view of the projectile; Figure 2
is a longitudinal section of the same; a, a, is the body of the shell, which I
make of the metal known as homogeneous iron, or of very mild lowly carbonized
steel; the metal is by the makers of homogeneous iron cast into an ingot, and
hammered so as to produce a bar of suitable section. Having obtained such
a bar, forged approximately to the form of the shells, I cut it into lengths,
each sufficient to form two shells; these lengths are then what is technically
termed "converted," so as to render the exterior part more highly carbonized,
and therefore harder than the interior, to a depth of from a quarter to half an
inch. These pieces I divide, and bring to the form shown in the Drawing,
boring them internally, and turning and cutting them externally. This being
done, I put the body of the shell into an iron box, and surround it with animal
charcoal, cuttings of horn, and such like materials ordinarily employed in the
process of case-hardening, and, as is usual in that process, I heat the box with
the body of the shell within it to a red heat. I then withdraw it, still red hot,
from the box, and having set it up on end, I cause numerous jets of cold
water, by preference brine, to play both on its outer and inner surfaces, thus
the shell body is rapidly cooled and rendered hard. In this state however it
is more brittle than is desirable; this I obviate by tempering it, for which

page_text: purpose I place it with its base on a block of metal, heated to dull redness,
and allow it to remain there until a straw color at the front and a blue color
at the rear indicate that it is tempered to the proper degree.
In Figures 1 and 2, 6 is a plug employed to close the passage through the
front of the shell; the object of forming this passage is to admit of the body
being more thoroughly hardened than it could be, were the shell made solid in
front; this plug before being screwed into its place is also hardened and
tempered. c is another metal plug screwed into the rear end of the shell, for
closing it after the charge has been introduced. The interior of the shell
may be painted or thinly covered with bitumen, marine glue, or other
substances, such as are used for giving a smooth internal surface to common
shells. The bursting charge, which may be powder, such as is commonly
employed for this purpose is then introduced, being first enclosed in a flannel
bag or case, in order to prevent the heat generated by impact from being
transmitted too rapidly to the bursting charge, and at the fore part of the bag, as
far, say, as the points marked x, x, several thicknesses of flannel are employed,
the number of thicknesses of flannel used being more or less, according to the
effect it is desired to produce; the longer the time, which it is desired should
elapse between the perforation of the armour plate and the explosion of the
shell, the greater will be the number of thicknesses of flannel employed. In
place of flannel, other materials which transmit heat slowly may be employed,
but flannel is, I believe, most convenient. By these means I am able to make
use of the heat generated on the impact of the shell with the armour
plating, to fire the bursting charge, after the shell has penetrated through the
plating.
Figure 3 is a longitudinal section of a form of shell, somewhat different
from that shewn at Figures 1 and 2. In this case the body a is not
bored through at the front. The shell need not be charged entirely with gun-
powder; there may be just sufficient powder put into it to rend it, and the
remaining space may be occupied by destructive or noxious chemical prepara-
tions. Gun cotton or compressed powder may be used with advantage for the
bursting charge; or explosive agents of a more energetic nature than these
may be employed.
The shells described may also be employed for penetration like solid shot,
as by removing the centre part of the forged piece, which is sometimes unsound,
I am able with great certainty to make the metal of the degree of hardness
required, and which is varied, as described in different parts of the body of
the shell..
The shells shown in the Drawing are adapted to be thrown from a

page_text: rifled gun with hexagonal bore; if a gun with any other form of bore be
employed, a corresponding change will have to be made in the external con-
figuration of the projectile.
I have found practically that a shell such as that shewn at Figures 1 and 2,
having a maximum diameter of seven inches, and propelled by 27 lbs. of
powder, will at a range of 800 yards penetrate with facility a five-inch wrought-
iron armour plate supported by a heavy backing of timber and iron skin. It
will be remarked that the shells shown in the Drawing are flattered in front,
and for penetrating armour plates it is very desirable that this form should be
given to them. Where the conditions are such that the shell can be made to
strike with its axis perpendicular, or nearly so, to the armour plating, a shell
rounded in front may be employed, although even under these conditions it will
not penetrate with the same facility as a properly formed flat-ended projectile,
but where the circumstances are such (as they would be in almost every prac-
tical case), that it is impossible to secure the shell striking with its axis perpen-
dicular, or nearly so, to the surface of the armour plating attacked, then a shell
rounded in front is deflected on striking the armour plating, and either glances
off entirely, or expends its momentum with more or less inefficiency according
to the inclination at which it strikes. Shells with flat ends are effective if the
object aimed at be below water. Shells constructed according to my Inven-
tion, may, if desired, be fitted with ordinary fuses, and it is in some cases
desirable so to fit them; they will not in this manner be rendered any more
useful for employment against armour plating for which they are primarily
intended, but the fuses will enable them to be fired with effect if necessary at
objects which will not offer resistance, so as to generate sufficient heat to fire
the bursting charge within it, as for example in attacking such a ship as the
"Warrior," which is only partly protected with thick armour plate, the fuse
would then insure the explosion of the projectile, which might not otherwise
occur were the shell not to strike the thick armour plate.
It will be observed that in the Drawing I have represented the shell smaller
at the flattened end than in the middle. This construction both assists its
flight, and enables it to penetrate the more readily. The front of the shell
on striking always produces a hole somewhat larger than itself, hence the body
of the shell notwithstanding its increased diameter will be able to follow
without experiencing much resistance. The taper in front should not be such
that the inclined shoulder would deflect the shell on being fired through water,
nor in being fired through a plate should its sides have to overcome lateral
resistance. Again the degree of convexity of the front must not be such as
will prevent it from taking hold or biting into the inclined surface of a plate.

page_text: It may be stated generally that Figure 4 represents the best form of pro-
jectile for flight as described in the Specification of my Patent of December
30th, 1859. See Figure 2, Sheet 1.
A parallel form would afford the greatest capacity for a bursting charge,
and also a front that would most readily bite into a surface greatly inclined.
The form which I find to be the best compromise for a penetration shell is
that shewn in Figures 1, 2; and 3.
In witness whereof, I, the said Joseph Whitworth, have hereunto set
my hand and seal, this Second day of December, in the year of our
Lord One thousand eight hundred and sixty-two.
JOSEPH WHITWORTH. (L.S.)