IMPROVEMENTS IN IRON FORTIFICATIONS, 'SUCH IMPROVEMENTS BEING APPLICABLE TO THE CONSTRUCTION AND PROTECTION OF SHIPS AND FLOATING BATTERIES.
Year: 1865

page_text: LETTERS PATENT to George Johnson, of Wandsworth, County Surrey,
Builder, for the invention of "IMPROVEMENTS IN IRON FORTIFICATIONS,
'SUCH IMPROVEMENTS BEING APPLICABLE TO THE CONSTRUCTION AND PROTECTION
OF SHIPS AND FLOATING BATTERIES.'
Sealed the 20th October, 1865, and dated the 1st May 1865.
PROVISIONAL SPECIFICATION left by the said George Johnson at the
Office of the Commissioners of Patents, with his Petition, on the 1st
May 1865...
1. GEORGE JOHNSON, of Wandsworth, County Surrey, Builder, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN IRON FORTI-
FICATIONS, SUCH IMPROVEMENTS BEING APPLICABLE TO THE CONSTRUCTION AND
PROTECTION OF SHIPS AND FLOATING BATTERIES,' to be as follows:-
This Invention consists in the following improvements, in the construction
'and 'formation of iron fortifications, and in the construction and protection of
the upper works or top sides of ships and floating batteries:--Firstly, the
formation of oblique sided or diagonally projecting casemates, which case-
mates are in conjunction with an inclined parapet or shelving breastwork, as
shewn in Diagramis, Sheets 1, 2, 3, 4, Figs. 1, 2, 3 4. Secondly, the
adaptation of a cylindrical revolving shield to embrasures for the protection of
guns mounted on the broadside principle: also an arrangement for utilising
and causing the recoil from the discharge of the gun to turn the shield round
and instantly close the port, as shewn in Diagram, Figs. 1, 2, 3, 4. Thirdly,

page_text: a system or process for joining and uniting together the armour plates, strakes,
or blocks of iron: also the ribs, beams, and all such like portions of the
materials used in the construction and protection of iron fortifications, ships,
and floating batteries by means of opposite dovetail or other undercut grooves,
and by the use or application of molten metal tongues to fill such grooves in
the manner shewn in Diagrams. Figs. 1 to 7.
The principles of this Invention will be ascertained by reference to the
accompanying Drawings.
Fig. 1. Sheet 1, is a horizontal section, and shews the construction and
formation of casemate, together with the lower portion of the inclined
parapet. a, a, represent sloping armour plates; b. b. supports to do. c. c,
oblique side walls of casemate (in this Diagram the cylindrical shield or
traversport is shewn in position, but should the casemate be used without the
shield, then in that case the front of the casement is protected by a wall, the
position of which is indicated by the dotted lines x; and at the centre of such
wall is the gun port); g. cylindrical shield pierced through by a port and
loophole in contrary directions; h, manhole; i, gün; k, slide: 1, port sill
(present only with the shield); m, space; n. pivoting eye attached to the
traversing slide; o. o. friction rollers, between which the connecting chain
passes; p. segment of iron fixed to the floor; q, q, tongues of metal, which in
a molten state is poured into and fill up the dovetail grooves; e, e, are port
jambs . chain; d. stringer.
Fig. 2, Sheet 2. represents the casemate, shield, and parapet complete as
seen on the top side. a, a, are sloping armour plates; b, port sill; c, space;
d, shield: e, hole; /. front roof plate; h, h, cross braces.
Fig. 3. Sheet 3, is a transverse vertical section of casemate shewn as
constituting a part of the battery of a ship or floating fortress. a. a, are
sloping armour plates; b. oblique flank wall of casemate; c, return end;
d. spandril framed supports: e, friction roller to guide the connecting chain;
9, gun; it, the connecting chain for closing the port; k, cylindrical shield;
I, port sill; n, a pivot on which the turntable revolves; o, o. rollers to reduce
the friction in moving the shield round; i, i, decks; j. bulwarks hinged to
turn down on deck; p, p, solid iron plates of breastwork or the side of vessel;
7. r, molten metal tongues running throughout every seam in the iron plates;
9, wrought-iron ribs.
Fig. 4. Sheet 4, is a reverse flank elevation casemate and parapet;
16, represent armour plates; t, spandril framed supports; u, oblique flank
wall; 2. return end; e, cylindrical revolving shield; y, port sill.
Fig. 5 is a horizontal section shewing the construction of the side, skin, or

page_text: defensive part of a vessel or fort: the plates are all joined to each other. and
are also joined to the ribs by the means of opposite dovetail grooves. and
molten metal run into such grooves to form corresponding tongues. a. a. arc
solid iron plates about twelve inches in thickness, grooved at their edges
wherever they meet. and tongued together as described in these plates
there are other grooves made on their inner face, such grooves coming opposite
to and corresponding with the direction of the ship's frames or ribs: b. b.
wrought-iron ribs or frames prepared with dovetail grooves. and are placed
opposite to the grooves which are made on the inside of the plates; c, c.molten
metal tongues: d. d. wood ribs or backing: c. e. pugging, composed of mortar.
sand. compressed oakum. or other suitable material: inner skin of iron or
wood. the fibre applied diagonally so as to brace the structure together in the
manner of rider plates.
Fig. 6 is a horizontal section or plan representing a mode of applying the
principles of the truss to the backing of armour plates in the construction of
ships or forts: this system effects the object of causing the force of impact
from a shot striking at any point to be dispersed over and sustained by a very
extended area. it dispenses with the employment of wood. and gives unity
throughout the entire structure. The ribs can be prepared to the given
section with the required grooves and abutments formed in the operation of
rolling. The trussing plates which extend diagonally from one rib to another.
the planes of which plates bisect each other. are rolled, having grooves and
projections, as shewn in the Drawing: the ribs and trussing plates are then
set up in their respective places, and molten metal is poured into the dovetail
grooves and consolidates the whole together. The outside iron skin of armour
plates may either be put together first in the manner described above, or it
may be applied after the backing has been formed, as convenience requires;
the interstices between the ribs and trussing plates are filled with sand or
other suitable substance, and solidified by compression or otherwise, the object.
being to check vibration and prevent oxidation in the iron.
Fig. is a horizontal section or plan shewing the method of applying
conjoint or other armour to protect wood or other vessels. forts. or batteries.
a. a. are armour plates of the usual description; these plates may or may not
he grooved and tongued together with molten meial: b. b. are flanged dovetail
grooved iron bars. which are fastened vertically to the side of the structure
that is to be protected: g. g. bolts or screws: d. outside planking: e. timbers
or ribs inner skin: c. c. molten metal tongues which fasten the armour
plates and the flanged dovetail grooved iron bars together: i. i. open spaces
for pugging.

page_text: Figs. 8, 9, 10, are different forms of keys intended to be used to hold and
fasten together any part of these structures where molten metal cannot be
conveniently applied.
mode of application.
The forms of these keys will suggest their use and
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Johnson in the Great Seal Patent Office on the
24th October 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME I, GEORGE
JOHNSON, of Wandsworth, in the County of Surrey, Builder, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by. Her Letters
Patent, hearing date the First day of May. 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 George Johnson. Her special licence that I. the said George Johnson,
my executors, administrators, and assigns, or such others as I, the said George
Johnson, 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 "IMPROVEMENTS IN IRON FORTI
FICATIONS, SUCH IMPROVEMENTS BEING APPLICABLE TO. THE CONSTRUCTION AND
PROTECTION. OF SHIPS AND FLOATING BATTERIES," upon the condition (amongst
others), that I. the said George Johnson, 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 Oflice within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said George Johnson, 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 relates to the following improvements in the construction of
iron fortifications, and in the construction and protection of the upper works
or top sides of ships of war and floating batteries, namely, first, a process to
unite and consolidate the armour plates, ribs, and other parts thereof;

page_text: second, a cylindrical self-closing shield to give extended training to and
protect guns mounted on the broadside principle: third, the construction of
oblique or angular projecting casemates employed in conjunction with low
sloping breastworks. for the effectual deflection of shot. First, to construct
the oblique casemate and sloping breastwork. I form the front face of such
shelving, breastwork. or parapet at an angle or tumble home of about thirty
degrees with the horizon; the glacis so formed is composed of thick armour
plates of the usual description, resting upon and secured to framed spandril
supports or wedge-shaped blocks, as shewn in the Drawings hereunto annexed,
Figs. and 4. Sheets 1 and 2: a backing of wood, stone, or other suitable
material may be employed, if desired, at such point. as it is intended to mount
a gun, a considerable portion of the glacis or shelving breastwork is omitted.
so as to leave an opening large enough to admit of the gun being run out
bodily and allow sufficient room for training to protect the gun in front and
flank. I construct partly within or upon such shelving breast work an angular
or oblique sided casemate: the enclosing walls of the flanks are at their
foremost ends, a distance of only a few feet apart: a short wall encloses the
front of casemate, in which wall there is a gun port. connecting the two flank
walls with each other, the flank walls becoming wider apart as they recede
backwards, finally terminating within or upon the sloping breastwork, and are
thereto conjoined: these oblique side walls of the casemate will deflect shot to
the right hand or to the left, whilst the shelving parapet will deflect shot in
an upward direction. The casemate is roofed with a strong iron grating, and
its whole construction is to be of the most solid description: the casemate will
be kept as small in area as practicable. having due regard to the character
and requirements of the gun to be used therewith, which gun may be
mounted and worked in the usual manner.
Second, this part of my Invention consists in the adaptation and application
of a cylindrical shield, barrier, or traverseport to embrasures for the protection
of battery or broadside guns; by the use of this shield a gun can be trained
through the arc of a quarter of a circle, that is, to be trained to an angle of
45 degrees either way, and still be completely protected.
In the following description of the above-mentioned shield, barrier, or
traverseport, the word traversepori only will hereafter be used to designate this
part of my favention. The traverseport consists of a cylindrical body about
eight feet in height, and about five feet in diameter; it may be composed of
steel. rolled iron. or homogenous metal: at or near the middle of the traverse-
port is a porthole, in width just sufficient to receive the chase of the gun,
and sufliciently high to allow of the elevation and depression of the muzzle; a

page_text: loophole to pass the handle of the ramrod out at when loading pierces
through the axis of the traverseport in the contrary direction to the porthole.
which it bisects and crosses at right angles. The traverseport is employed
jointly with the oblique sided casemate and shelving parapet above described;
it is placed in the advanced angle of the casemate and directly before the gun
in the position shewn in Diagram, Figs. 1. 2. & 4. Sheets 1 and 2: its base or
lower extremity extends to a few inches below the surface of the deck or floor,
or it may terminate within a retaining flange or ring fixed to the floor. A
pivot for the base of the traverseport to revolve upon and keep it central can
be used for floating batteries, but where the traverseport can hold a perpen-
dicular position, as will be the case in land batteries, it is preferred without
any fixed centre of rotation; this method of mounting being best calculated to
successfully resist severe blows; its base end is turned in a lathe or otherwise
brought to a true plane: the substance of the metal below the top of the port
sill may be reduced to about two inches in thickness, above that part great
thickness will be given. The traverseport is supported by and revolves upon
a turntable, which turntable consists of a central boss turning on a pivot
which is fixed to the floor, and rollers about eight in number. which rollers
radiate from the centre boss and preserve their proper radi by means of
projecting bearings made in connection with the boss. A fixed circular rail
supports the outward extremities of the rollers, so as to receive the pressure
transmitted in a direct line through the rollers from the traverseport. thus the
friction will be reduced to a minimum. Openings made through the floor
under the turntable will assist the ventilation of the rooms or decks beneath;
to prevent the jamming of the traverseport a space of about fifteen inches
wide is left on each side. these spaces can remain open. or they may be closed
by solid upright jambs about one foot in thickness. so placed that their front
faces will stand in a line somewhat behind the centre of the traverseport (as
shewn in Diagram, Fig. 1, Sheet 1). by reason that if these should be struck
by shot and driven inwards in any degree, the result would not jamm or
impede the working of the traverseport, but on the contrary would give more
room for it to revolve in grooves cut across the jambs and leading in an
outward direction will extend the field view, and also facilitate rifle firing:
any remaining interstices may be covered with mantlets or by rifle-proof
shutters applied internally. The working of the traverseport in connection
with the gun is carried into effect in the following manner: A circle of iron,
which term the pivoting eye, loosely surrounds the traverseport at the level
of the slide used for training the gun, and to which slide the pivoting eye is
rigidly attached; the said eye works between guides placed at its periphery,

page_text: which guides are so fixed as to keep the said eye central with the traverseport.
and yet avoid friction thereon in passing round it. the traverseport will thus
become the inimaginary centre around which the gun is trained. The self-
closing of the port is accomplished by utilizing the recoil of the gun. and is
effected in the following manner:-The traverseport and the gun are
connected together by a chain, as shewn in Diagram. Figs. 1 & 4. Sheets 1 and 2.
this chain passes between guide pullies fixed upon and near to the fore end of
the slide platform. Diagram Fig. 4. Sheet 2, is a sectional representation
of the traverseport in a position in which the port is virtually closed, in
consequence of its direction being adverse to the line of fire, as will be the
case during the time the gun is being loaded. When the gun has to be fired
hand spikes or leavers are inserted into mortice holes provided at the lower
part of the traverseport, and are actuated by men who cause the traverseport
to turn round to the extent of a quarter of a revolution; by this movement
the gun is simultaneously drawn forward by the connecting chain, so as to be
ready to enter the port now in a line with the gun, which is then run out and
discharged through the traverseport: the gun recoils, and the instant the
muzzle has quitted the port hole the gun begins to pull the connecting chain
and so continues to do whilst retiring a distance of about four feet, whereby
the traverseport revolves back again and assumes its former position. that is
to say, the loop hole will again be in a line with the gun whilst the port hole
will lie in the contrary direction, and thus present the solid sides of the
traverseport to the enemy, and consequently complete protection will be given
to the gun and men; the operations just described can be performed in a few
seconds, and are generally to be repeated at every discharge. particularly
when engaging an enemy at short range. A break can be applied to the
traverseport to retard its revolution, and take up any excess of recoil, and stop
bolts or catches may be used to fix the traverseport as may be required.
Third, this part of my Invention consists in a system or process for joining
together pieces of iron. such as armour plates, the ribs. and other parts of
ships of war, batteries, or fortifications, and by which to impart great strength
by and upon the following plan: The thick armour plates. blocks. or strakes
of iron of proper form and suitable dimensions are grooved all round upon
their edges. or wherever they are to come in contact with one another; each
piece is grooved at about the centre of its thickness. and parallel with its
surfaces with a dovetail or other undercut groove; the width of the groove
will be equal to about one-third the thickness of the plate, and of proportionate
depth. similar grooves are also formed in their inner faces transversely to their
lengths, and at proper intervals to suit and fasten the plates to the ribs or

page_text: frames of the ship; each rib or frame is prepared with a dovetail groove at
the edge that comes next to the armour plates. These dovetail grooved plates
and ribs will be seen in the sectional Diagrams, Figs. 4 & 5, Sheet 2. la
constructing a vessel the said ribs or frames are moulded to the intended lines
of the vessel, and are then set up in their respective positions, according to
the usual practice in naval architecture, assuming the bottom of the vessel to
be of wood or of some different construction, and already prepared as far as
where the thick plating is required to commence; a plate is laid upon the
substructure, the face of the plate having the transverse grooves above
described is inwards and abuts against the ribs, so that the grooves in the
plate are opposite to the grooves in the ribs. I then pour metal in a molten
state into the opposite dovetail grooves, and fill them up from the bottom to
the top edge of the plate; the metal is then suffered to cool, and by these
means the plate is firmly fixed to the ribs; the same operation will be repeated
to fix every successive plate. As the work proceeds the grooves in the edges of
the plates will be brought opposite to one another, and all grooves so brought
together to be filled up with molten metal in like manner; the melted metal
should be as fluid as possible, and being poured in at the top of a vertical
seam it will flow along through the horizontal seam below it until both are
filled up each succeeding course of plates must well overlap or break joint
with that previously fixed; it is obvious that by following the above described
process plate will become joined to a plate, all the plates joined to the ribs or
frames, and the entire structure of a ship, fort, or battery be consolidated into
one massive compact piece of immense strength. I have to observe that in
carrying out this system of uniting armour plates. &c., accuracy of fit in the
various joints is not absolutely necessary; if occasional fissures as much as an
inch in width should exist the flow of metal will fill up any irregularities or
spaces that are left, and render the seams water-tight.
The usual and all necessary precautions used in casting metal are to be
observed to prevent the molten metal escaping from the seams and indents, or
notches may be made in the grooves to produce corresponding irregularities in
the tongues, and thereby prevent the possibility of one part sliding upon
another.
Armour plates for the protection of wooden vessels can also be fastened by
the application of molten metal, and be conjoined by the process above
described upon the plan shown in Diagram, Fig. 6. Sheet 2. According to this
Invention the ribs for fastening the plates to a ship's side consist of flat
flanged bars of iron, having a dovetail groove in each: these bars are screwed
or bolted through their flanges to the vessel, their position being vertical and

page_text: corresponding to the ribs of the vessel; to these bars the armour plates are
attached by filling the opposite dovetail grooves up flush with molten metal, as
previously stated; no bolt will thus pass through or even into the plates, and
thereby the perforations for armour bolts which offer a direct channel for
water to leak into the vessel and necessarily weaken the plates, is avoided.
The accompanying Drawings, which are numbered and lettered for
reference, will clearly ascertain the nature of this Invention.
EXPLANATION OF THE DRAWINGS.
Fig. No. 1, Sheet 1, is a horizontal sectional plan shewing the construction
and arrangement of casemate with the lower portion of shelving breastwork
or parapet. a, a, are sloping armour plates of parapet; b, b, supports to ditto:
c, c, oblique flank walls of casemate, the dotted lines × indicate the position
of the front wall previously mentioned, connecting the two flank walls of a
casemate in which the traverseport is not used; d, stringer to support flank
wall and port jamb; e, e, port jambs: /, the connecting chain by which the
recoil closes the port, shewing its disposition and how its ends are attached.
one end to the traverseport at a point under the loophole, the other end is
carried round the guns cascable, and forms a nose; g, traverseport, shewing
the respective positions of loop holes and port hole; h, man hole to give access
to the turntable, and to serve for ventilating purposes; i, gun; k, slide;
1. port sill: m, space; a, pivoting eye; o, o, friction rollers for the connecting
chain to pass between; p, segment or ring secured to the floor; q, q, tongues
of molien unetal.
Fig. 2, Sheet 2, is an external view of the oblique casemate, sloping
parapet, and traverseport complete, as seen from the top. a, a, are sloping
armour plates; b, port sill; c, space; d. traverseport; e, hole for lifting it by;
1, front plate of roof of casemate, with a semicircular cavity that receives and
supports the upper end of the traverseport; g. 9, iron bars of grated roof;
h, h, cross braces; i, i, return ends of casemate.
Fig. 3, Sheet 1, is an outline of a floating battery constructed on the
principle of this Invention, intended to shew the different bearings of the
guns, two of which will fire in a line with the keel both fore and aft; every
point of the compass is under command at the same time, whilst the batteries
will deliver broadsides to the angle of forty-five degrees with the keel either
way, each gun commanding the arc of ninety degrees, or a quarter of a
circle.
Sheet 2, Fig. 4, represents a vertical section of a casemate and the upper
works of a vessel or floating battery. a, u, are sloping armour plates;

page_text: b, oblique flank wall of casemale; c, return end of ditto; d. spandril supports
to sloping armour; e, friction roller of connecting chain; g, gun; h, connecting
chain, traverseport, the handle of the ramrod is shewn as it would be put
through the loophole in the act of loading: 1. port sill: m, fender or a circular
plate fixed to the port sill to prevent fragments of shells or dirt going below;
n, pivot on which the turntable revolves; o, o, radial rollers and radial bearings
guide plate; i, i, decks; i, bulwarks hinged to turn down upon the decks on
going into action; p, p, solid iron plates composing the ship's side; r, r,
molten metal tongues that run throughout every seam; s, s, wood planking of
ship's bottom; q. wrought-iron ribs. The following description relates to the
flank elevation shewn in this Diagram:- represents spandril framed support;
w, armour plates; u, oblique flank wall; z, return end; v, traverseport;
y, port sill.
Fig. 5, Sheet 2, is a horizontal section shewing the construction of the top
sides of a ship, battery, or fortification according to this principle. a, a, are
solid iron plates about twelve inches in thickness, having dovetail grooves in
their edges where they meet each other; and transverse grooves on their inner
sides where they meet the ribs; b, b, wrought-iron ribs or frames prepared
with dovetail grooves placed opposite to the vertical or transverse grooves in
the plates; c, c, molten metal tongues; d, d, wood ribs or backing: e, e, is a
pugging of bitumen, cement, mortar, or other suitable material; f. inner skin
applied diagonally so as to act as rider plates.
Fig. 6. Sheet 2, is a horizontal section shewing this method of applying
and fastening armour plates to already constructed ships, forts, or batteries.
,, are armour plates of the usual description, (the seams grooved with
dovetail grooves, and joined together with molten metal, as previously
described the same transverse grooves are cut on the inside faces, as shewn
and described above); b, b, flanged dovetail grooved iron bars screwed or bolted
vertically to the ship's side, &c.; g, g, bolts or screws; d, outside planking;
c, ribs of timber; /, inner skin; c, c, molten metal tongues which fasten the
plates to the bars; i, i, are open spaces which are to be pugged, as previously
described.
Fig. 7, Sheet 2, represents a horizontal section or plan of a method of
applying to the backing of armour plates the properties of the truss by which
great strength and unity of substance are obtained; the force of shot striking a
target constructed on this principle will be transmitted from rib to rib and
dispersed over a widely extended area; the ribs and trussing plates of rolled
iron are prepared to the required section, and the dovetail. groves formed in
the process of rolling as far as practicable; the ribs I prefer to have in one piece,

page_text: equal in length at least to the depth or height of all the armour plates, but
where convenience requires it the trussing plates may be in sections, each
section a few feet only in length; the armour plates, ribs, and trussing plates
are placed in their relative positions, and are then successively joined together
by pouring molien metal into the dovetail grooves. as before described; the
interstices formed between the ribs and plates are filled with cores of sand or
some suitable composition that will preserve the iron from oxidation, and prevent
leakage, and check the vibration arising from heavy blows: if necessary, an
inner skin composed of iron plates about three-quarters of an inch thick may
be used; these plates are to be applied in the manner of braces raking to an
angle of about forty-five degrees, and are to be secured to the ribs by short
bolts and nuts, the heads of which are slid into the dovetail grooves at the
edges of the ribs, and are held thereby.
Figs. 8, 9, 10, Sheet 2, are representations of different forms of divided
keys designed to hold together various parts of these structures, and to be
used where the molten metal may be inconvenient or inapplicable, as, for
instance, in uniting wood with iron, or wood with wood, they form each
a double dovetail tongue, and may be made in lengths of from a few
inches to one or two feet each. Fig. 8 is a key divided diagonally, and is
therefore in the form of a pair of wedges; Fig. 9 is divided into three
parallel portions; and Fig. 10 is similar to the last, but different in section;
the mode of applying these keys is obvious and will not require further
explanation.
Having hereby ascertained the nature of the said Invention, and described
in detail in what manner the same is to be performed. I have to observe that
I do not bind myself to use the exact form or the precise arrangement of the
parts thereof, nor to the dimensions given, or the employment of iron where
steel is preferable, as it is obvious that all these may be varied in practice
according to circumstances without changing the principle; I claim as my
Invention,
First, the construction of oblique sided casemates, which casemates project.
froin and are in conjunction with shelving breastworks.
Second, the adaptation of the traverseport for the protection of guns in
broadside batteries, also the principle of turning the traverseport round by the
application of the recoil of the gun, by effect of which the port is instantly
closed.
Third, the process of joining together the armour plates, ribs, and other
portions of ships, batteries, and forts. by the means of opposite dovetail or
other undercut grooves and molten metal.

page_text: And I claim all applications thereof as may be legal under Letters
Patent.
In witness whereof, I. the said George Johnson, have hereunto set my
hand and seal. this Twenty-third day of October, in the year of our
Lord One thousand eight hundred and sixty-five.
GEO. JOHNSON. (L.S.)