ARMOUR PLATES FOR VESSELS OF WAR AND FOR OTHER SIMILAR PURPOSES.
Year: 1865

page_text: ARMOUR PLATES FOR VESSELS OF WAR AND FOR OTHER SIMILAR PURPOSES.'
PROVISIONAL SPECIFICATION left by the said John Brown at the
Office of the Commissioners of Patents, with his Petition, on the
17th February 1865.
I, JOHN BROWN, of Sheffield, in the County of York, Iron and Steel
5 Manufacturer, do hereby declare the nature of the said Invention for "IM-
PROVEMENTS IN ARMOUR PLATES FOR VESSELS OF WAR AND FOR OTHER SIMILAR
PURPOSES," to be as follows:-
This Invention consists in deeply grooving the outer face of iron plates or
armour slabs, which generally constitute the exterior side of the ordinary iron
0 casing of vessels of war and armoured fortifications, so as to form longitudinal
ridges, taking care, however, that they shall run in a horizontal direction when
the plate is fixed in its place. The salient angle formed by the lateral planes
of the ridges should measure 90 degrees or thereabouts, that is to say, the

page_text: angle which will enable the most power to be absorbed from the shot with the
least damage to the plate from the diverging resultants of the force represented
by the impinging projectile. The bottom of the groove may be either angular
or plane, in either case it should receive one or more shallow ridges, the
lateral sides of which may form acute angles. The opening and depth of the 5
grooves should be such that projectiles of large calibre when fired for the
purpose of penetrating these plates will be compelled to lodge in the grooves,
and therein take a plurality of surfaces of contact, as well as crush in the
shallow ridges, the object being on the part of the plates to increase the
amount of work that the shot has to do at the first moment of penetration, 1
and thereby facilitate the absorption on the part of the armour, and the con-
sumption on that of the projectile of the force of impact. The thickness of
the plate must be sufficient to resist disruption, support the ridges, and defy
the power left to the shot after the special action exercised by the plurality of
contact surfaces ceases through the projectile getting deeply immerged into 1
the substance of the plate, from which moment the conditions of resistance to
penetration become assimilated to those of the ordinary slabs now in general
use for structures intended to be shot proof.
As a constituent part of the same Invention the backing immediately to the
rear of the grooves and in contact with the plate is transformed into a
powerful element of strength by the introduction of metallic troughs (iron or
steel) running horizontally, the open side pressing against the plate while the
wedge-shaped rear is turned towards the skin or frame of the structure. This
peculiar arrangement enables me again to bring into play the principle of a
plurality of contact surfaces, because if the shot pierces the plate at the
grooves it will lodge in both the supporting sides; it moreover assists in
stiffening the structure at the moment when the flexure caused by the blow
tends to open the whole and disjoin the various parts of which it is con-
stituted, and lastly it has the great advantage of circumscribing the damaging
effect of live shells because the explosive charge could not hereby act beyond
the
space enclosed by the lateral iron sides. These "troughs" are intended to
be filled with timber.
Always as a constituent part of the same Invention I place in the rear of
these iron "troughs," and consequently in the rear likewise of the grooves
within which the projectile is compelled to force its passage, a horizontal iron
framework of great solidity and elasticity to support the former, to enliven the
resistance by developing a powerful amount of "reactive force," and to disperse
over the structure the concussion produced by the blow. This framework is
composed of T iron, the vertical branch being prolonged about an inch or two

page_text: on the opposite side, with the object of forming a small ridge for the small
trough to rest upon, while the lower vertical arm runs between a double row
of angle irons riveted or otherwise fixed to the iron skin. To every groove of
the plate's face corresponds one of these horizontal constructions, the top branch
5 of the T iron being midway or thereabouts between the rear face of the
armour and the skin. Lastly, to connect the plate with the skin and with the
horizontal frames I make use of a second skin A-shaped, the salient edge of
which supports the plates, receives the through bolts, and corresponds to the
salient of the plate, while the lower ends rest on the T iron plates of the outer
10 frame. Thus, commencing at the skin, I rivet, bolt, or otherwise fix to it as
many horizontal double rows of angle irons as there are salients in the outer
face of the armour plates. I then fill up the space between these rows with
timber, oak, or teak or any suitable wood exceeding the ridges of the angle
irons by about 2 inches. I then fix the irons in their proper position,
5 drawing them as closely as possible to the skin of the arm, vertical in this
figure T, but horizontal in the structure, sliding tightly in the groove left
between the two corresponding angles. It will however be useful to avoid
bringing the upper plate of the T on to the extreme foremost lines of the
angle irons, and likewise avoid resting the extreme end of the vertical arm
(horizontal in the structure) against any harder substance than wood, because
the immediate contact of hard metals across the direction which penetration
must necessarily take is detrimental to the distribution of the shock over a
maximum area as well as to the gradual extension of vibration from the exterior
to the interior. By properly attending to this construction "frame cushions" of
great strength and elasticity are thereby ensured to the backing. The A timber
is then put on, followed by the A shaped skin, the latter firmly fixed to the
upper plates of the T irons. A system of "large troughs" is thus formed, the
sides of which are most useful in dispersing the concussion over a great area.
These troughs have then to be filled up with suitable timber, and the "small
troughs," inserted one for every corresponding groove of the armour plates, for
the reception of which the structure is now ready. On a shot striking it
would have to take a plurality of contact surfaces in the grooves, crush down
the shallow ridges, pierce the slab, lodge between the two sides of the small
troughs, overcome their resistance, take a plurality of contact surfaces with
respect to the A skin, and then break through the outer frames or rows of
horizontal "frame cushions" before it could come into contact with the skin.
Wherefore I believe this system of armour plating does present the best
possible conditions of resistance that can reasonably be expected from a given
weight, and so far fully capable of counterbalancing the superiority recently

page_text: ]
acquired by artillery through the introduction of monster cannon and indes-
tructible steel shot. It differs from the ordinary armour in this essential
respect that while in the latter the element of resistance must necessarily be
uniformly spread over the whole area, in the former it is accumulated along
narro wstripes of the protected surface, because it is only in these stripes of the 5
armour that penetration can be effected, if at all. It also differs in another
respect, namely, that in ordinary armour plating the plain slab presents no
more than one point of contact to the impinging shot at the instant in which
the latter takes effect. This is the worst possible disposition that can be taken
to ensure resistance, because, firstly, the area over which the shock is dis-
tributed in the rear will be a minimum independently of the nature of the
backing, whether compound or simple, because, secondly, the area of first
contact does not increase with the calibre, whence it follows that by doubling
the diameter of the projectile the force thrust upon this constant area increases
for equal velocities in the ratio of the cube, namely as 1:8 clearly indicating
the plan which must eventually lead shot to destroy such means of defence,
and, thirdly, because the stored up work when at its greatest height is not
carried off quickly enough before the pressure exerted by the shot has
disagregated the molecular cohesion of the plate around the point of impact
and produced rupture. In my Invention, on the contrary, armour gives a
maximum area of distribution in the rear for a given thickness, increases the
radius of such area as the diameter of the projectile is made greater, and
carries off the stored up work about three times quicker, there being no less
than three contact surfaces,
The idea of grooving plates to improve their resistance is not new in a
mechanical point of view, but most of the inventions founded on this plan
refer to the bending of plates so as to present a corrugated surface, each plate
forming one single salient or one single re-entering angle. One case
embodies the idea of grooving the outer face, the rear being flush, yet the
grooves establish only one sort of ridges, while their object is neither defined
nor comprehensible, since it is stated that the grooves may be either horizontal,
vertical, or inclined. In another case a succession of corrugated iron plates
is suggested, the bolts coming out at the bottom of the re-entering angles.
In a still more recent Patent grooving is proposed for deflection, the depth of
the channel being sufficient to cause the shot "to 'plant off' in the direction
given to its course by the form of the corrugation" against which it impinges
This species of armour has to be covered with plates of iron of a plain surface
and the space between the two filled up with wood or other suitable material
It is remarkable that in all cases no connection is established between th

page_text: groove
and the resistance of the backing. In my Invention I entirely differ
from these views, in fact, I establish wide and deep grooves running in hori-
zontal directions to contain one or more minor ridges, and I rely not on the
principle of deflection, but on that of attraction, if I may so express the force
that compels a shot to lodge within given planes. This attraction I advan-
tageously employ to make the shot spend part of its force in crushing down
the minor or shallow ridges, feature not only novel but quite as valuable as
the resistance due to the sides of the main grooves when taken into conside-
ration as a strong element of retardation thrown in the way of the projectile's
progress. Furthermore, I turn to good account the limitation and demar-
cation of the area through which the projectile must necessarily pass before
reaching the skin and frame of the structure to accumulate in that narrow
space a very high amount of elastic resistance, always in harmony with the
principle of a plurality of contact surfaces; and, lastly, I so arrange my back-
ing that the armour slabs are suspended from the resting point of the bolts,
and not at many inches distance from such resting points as is the case in the
"Warrior," the "Minotaur," and other well-known targets.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Brown in the Great Seal Patent Office on the 16th
August 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
BROWN, of Sheffield, in the County of York, Iron and Steel Manufacturer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventeenth day of February, in the year of our
Lord One thousand eight hundred and sixty-five, in the twenty-eighth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said John Brown, Her special licence that I, the said
John Brown, my executors, administrators, and assigns, or such others as I,
the said John Brown, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times there-
after 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 ARMOUR PLATES FOR VESSELS OF WAR AND FOR OTHER SIMILAR
PURPOSES," upon the condition (amongst others) that I, the said John Brown,

page_text: 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 5
the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Brown, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
-
This Invention consists in deeply grooving the outer face of iron plates or
armour slabs which generally constitute the exterior side of the ordinary iron
casing of vessels of war and armoured fortifications, so as to form longitudinal
ridges, taking care however that they shall run in a horizontal direction when
the plate is fixed in its place. The salient angle formed by the lateral planes
of the ridges should measure 90 degrees or thereabouts, that is to say the
angle which will enable the most power to be absorbed from the shot with the
least damage to the plate from the diverging resultants of the force represented
by the impinging projectile. The bottom of the groove may be either angular
or plane, in either case it should receive one or more shallow ridges, the lateral
sides of which may form acute angles. The opening and depth of the grooves
should be such that projectiles of large calibre when fired for the purpose of
penetrating these plates will be compelled to lodge in the grooves and therein
take a plurality of surfaces of contact as well as crush in the shallow ridges, the
object being on the part of the plates to increase the amount of work that the shot
has to do at the first moment of penetration, and thereby facilitate the absorp-
tion on the part of the armour, and the consumption on that of the projectile
of the force of impact. The thickness of the plate must be sufficient to resist
disruption, support the ridges, and defy the power left to the shot, after the
special action exercised by the plurality of contact surfaces ceases through the
projectile getting deeply immerged into the substance of the plate, from
which moment the conditions of resistance to penetration become assimilated
to those of the ordinary slabs now in general use for structures intended to be
shot proof.
As a constituant part of the same Invention the backing immediately to the
rear of the grooves and in contact with the plate is transformed into a power-
ful element of strength by the introduction of metallic troughs (iron or steel)
running horizontally, the open side pressing against the plate while the wedge
shaped rear is turned towards the skin or frame of the structure. This peculiar

page_text: 0
arrangement enables me again to bring into play the principle of a plurality of
contact surfaces, because if the shot pierces the plate at the grooves it will
lodge in both the supporting sides; it moreover assists in stiffening the
structure at the moment when the flexure caused by the blow tends to open
5 the whole and disjoin the various parts of which it is constituted, and lastly, it
has the great advantage of circumscribing the damaging effect of live shells,
because the explosive charge could not hereby act beyond the space enclosed
by the lateral iron sides. These "troughs" are intended to be filled with
timber.
Always as a constituant part of the same Invention I place in the rear of
these iron "troughs," and consequently in the rear likewise of the grooves
within which the projectile is compelled to force its passage, a horizontal iron
framework of great solidity and elasticity to support the former to enliven the
resistance by developing a powerful amount of "reactive force" and to disperse
5 over the structure the concussion produced by the blow. This framework is com-
posed of T-iron, the vertical branch being prolonged about an inch or two on the
opposite side with the object of forming a small ridge for the small trough to rest
upon while the lower vertical arm runs between a double row of angle irons
riveted or otherwise fixed to the iron skin. To every groove of the plate's
face corresponds one of these horizontal constructions, the top branch of the
T iron being midway or thereabouts between the rear face of the armour and
the skin. Lastly, to connect the plate with the skin and with the horizontal
frames I make use of a second skin A-shaped, the salient edge of which
supports the plates, receives the through bolts and corresponds to the salient of
the plate while the lower ends rest on the T-iron plates of the outer frame.
Thus commencing at the skin, I rivet, bolt, or otherwise fix to it as many
horizontal double rows of angle irons as there are salients in the outer face of
the armour plates. I then fill up the space between these rows with timber,
oak or teak, or any suitable wood exceeding the ridges of the angle irons by
about 2 inches. I then fix the T-irons in their proper position, drawing them
as closely as possible to the skin of the arm, vertical in this Figure T, but
horizontal in the structure, sliding tightly in the groove left between the two
corresponding angle irons. It will however be useful to avoid bringing the
upper plate of the T on to the extreme foremost lines of the angle irons, and
likewise avoid resting the extreme end of the vertical arm (horizontal in the
structure) against any harder substance than wood, because the immediate
contact of hard metals across the direction which penetration must necessarily
take is detrimental to the distribution of the shock over a maximum area as

page_text: well as to the gradual extension of vibration from the exce
rior.
put
"
By properly attending to this construction "frame cushions" of great strength
and elasticity are thereby ensured to the backing. The A timber is then
on followed by the A-shaped skin, the latter firmly fixed to the upper plates of
the T-irons. A system of large "troughs" is thus formed, the sides of which
are most useful in dispersing the concussion over a great area. These "troughs
have then to be filled up with suitable timber, and the "small troughs" inserted
one for every corresponding groove of the armour plates for the reception of
which the structure is now ready. On a shot striking, it would have to take
a pluralty of contact surfaces in the grooves, crush down the shallow ridges,
pierce the slab, lodge between the two sides of the small troughs, overcome their
resistance, take a plurality of contact surfaces with respect to the A skin, and
then break through the outer frames or rows of horizontal "frame cushions"
before it could come into contact with the skin. Wherefore, I believe this
system of armour plating does present the best possible conditions of resistance
that can reasonably be expected from a given weight, and so far fully capable
of counterbalancing the superiority recently acquired by artillery, through the
introduction of monster cannon and indestructible steel shot. It differs from
the ordinary armour in this essential respect, that while in the latter the
element of resistance must necessarily be uniformly spread over the whole area,
in the former it is accumulated along narrow stripes of the protected surface
because it is only in these stripes of the armour that penetration can be
effected, if at all. It also differs in another respect, namely, that in ordinary
armour plating the plain slab presents no more than one point of contact to
the impinging shot at the instant in which the latter takes effect. This is the
worst possible disposition that can be taken to ensure resistance, because, firstly,
the area over which the shock is distributed in the rear will be a minimum, inde-
pendently of the nature of the backing, whether compound or simple, because,
secondly, the area of first contact does not increase with the calibre, whence it
follows that by doubling the diameter of the projectile, the force thrust
this constant area increases, for equal velocities in the ratio of the cube,
upon
namely as 1 to 8, clearly indicating the plan which must eventually lead shot
to destroy such means of defence; and, thirdly, because the stored
when at its greatest height is not carried off quickly enough before the
exerted by the shot has disagregated the molecular cohesion of the plate around
the point of impact and produce rupture. In my Invention, on the contrary,
armour gives a maximum area of distribution in the rear for a given thickness,
increases the radius of such area as the diameter of the projectile is male
up work
pressure
S

page_text: greater and carries off the stored up work about three times quicker, there
being no less than three contact surfaces.
In
The idea of grooving plates to improve their resistance is not new in a
mechanical point of view; but most of the Inventions founded on this plan
refer to the bending of plates so as to present a corrugated surface, each
plate forming one single salient or one single re-entering angle. One case
embodies the idea of grooving the outer face, the rear being flush, yet the
grooves establish only one sort of ridges, while their object is neither defined
nor comprehensible since it is stated that the grooves may be either horizontal,
vertical, or inclined. In another case a succession of corrugated iron plates is
suggested, the bolts coming out at the bottom of the re-entering angles.
a still more recent Patent grooving is proposed for deflection, the depth of the
channel being sufficient to cause the shot "to 'plant off' in the direction given
to its course by the form of the corrugation" against which it impinges. This
species of armour has to be covered with plates of iron of a plain surface, and
the space between the two filled up with wood or other suitable material. It is
remarkable that in all cases no connection is established between the groove
and the resistance of the backing. In my Invention I entirely differ from
these views, in fact I establish wide and deep grooves running in horizontal
directions, to contain one or more minor ridges, and I rely not on the principle
of deflection but on that of attraction, if I may so express the force that
compels a shot to lodge within given planes. This attraction I advantageously
employ to make the shot spend part of its force in crushing down the minor
or shallow ridges, feature not only novel but quite as valuable as the resistance
due to the sides of the main grooves when taken into consideration as a strong
element of retardation thrown in the way of the projectile's progress. Further-
more, I turn to good account the limitation and demarcation of the area
through which the projectile must necessarily pass before reaching the skin and
frame of the structure to accumulate in that narrow space a very high
amount of elastic resistance always in harmony with the principle of a
plurality of contact surfaces. And, lastly, I so arrange my backing that the
armour slabs are suspended from the resting point of the bolts and not at
many inches distance from such resting points as is the case in the "Warrior,"
the "Minotaur," and other well known targets. The angle irons can be
modified with ease without thereby destroying the object they have to fulfil
both as regards resistance to penetration in the immediate vicinity of the skin
no less than in respect of the additional strength they impart to the structure.
Thus each couple can be joined together and transformed into an open

page_text: Likewise the iron which stands in the rear of the
may be
U-shaped trough.
grooves made in the armour plate, and is consequently placed in front of the
wider opening left between the opposite angle irons of the cushion
deprived of its lower branch, and the ridges or ridge placed at the bottom of
grooves made in the outer face of the armour plate can be made circular 5
the
as well as angular.
The accompanying Drawing, forming part of this Specification, illustrates the
construction above set forth; A indicating the plate or slab grooved in B
according to the principles for eliciting a plurality of contact surfaces; C, the
shallow ridges which are crushed upon impact. The distance from ridge to 1
ridge is 14 inches in this case, and is therefore such combined with the depth
of the groove, namely, 5 inches to grasp such shots as are used in the heavier
nature of modern ordnance, as the 10 inch or 13 inch calibres. The minimum
thickness is here 5 inches, the maximum 10 inches, and as the angle formed
by the planes which constitute the ridges is in this case 90°, it therefore follows
In the rear of the
that the widest base of the ridge measures 10 inches.
plate we have the backing and cushion combined. The backing is more
particularly constituted, firstly, of the trough irons D, resting on the T-irons E;
secondly, of the wedges F, which should be omitted in such cases as the
application of flat armour slabs to the said backing. The space between the
ironwork of the backing is filled with timber or other suitable material. The
depth of the backing measures in this case 12 inches. This backing may rest
on a planking of about one inch in thickness, which may form the outer
surface of the cushion itself, composed of the angle or U irons G, G,
accordingly, as they are either separated as in 9, 9, or joined as at G, G.
The spaces between the angle irons are filled up with timber or other suitable
material and well caulked,
Having now described the nature of my said Invention and means by which
I carry it into practical effect, I would here observe that I do not confine
myself to the precise details herein given or shewn, as such may be modified to
suit the circumstances of particular cases without in any way departing
from the principle of my Invention, and I claim the exclusive use as of my
Invention,-
Firstly, of the slab made and constructed as described and shewn ;
Secondly, of the backing made and constructed as described and shewn,
whether used with or without the wedge E;
Thirdly, of the cushion made and constructed as described and shewn;
Lastly, I claim the exclusive use of the combination of slab backing and

page_text: cushion forming, when constructed and combined as herein directed, "Improve-
ments in Armour Plates for Vessels of War and for other similar Purposes."
my hand
In witness whereof, I, the said John Brown, have hereunto set
and seal, this Fifteenth day of August, in the year of our Lord One
thousand eight hundred and sixty-five.
JOHN BROWN. (L.S.)