IMPROVEMENTS FOR FOR THE PRESERVATION FROM CORROSION. OF RUDDER PINS AND GUDGEONS OR BRACES, SCREW PROPELLER SHAFTS THE WORKING PARTS OF FEATHERING PADDLE WHEELS, AND THE SURFACES Sammy QUIDS AND OTHER STRUCTURES." PROVISIONAL SPECIFICATION
Year: 1868

page_text: LETTERS PATENT to Noel West aud Robert Gibson West, both of
Palace Square, Upper Norwood, in the County of Surrey, for the
Invention of "IMPROVEMENTS FOR
FOR THE PRESERVATION FROM CORROSION.
OF RUDDER PINS AND GUDGEONS OR BRACES, SCREW PROPELLER SHAFTS
THE WORKING PARTS OF FEATHERING PADDLE WHEELS, AND THE SURFACES
Sammy QUIDS AND OTHER STRUCTURES."
PROVISIONAL SPECIFICATION left by the said Noel West and Robert
Gibson West at the Office of the Commissioners of Patents, with
their Petition, on the 30th November 1868.
We, NOEL WEST and ROBERT GIBSON WEST, both of Palace Square,
Upper Norwood, in the County of Surrey, do hereby declare the nature
of the said Invention for "IMPROVEMENTS FOR THE PRESERVATION FROM
CORROSION OF RUDDER PINS AND GUDGEONS OR BRACES, SCREW PROPELLER SHAFTS,

page_text: THE WORKING PARTS OF FEATHERING PADDLE WHEELS, AND THE SURFACES OF
IRON AND STEEL SHIPS, AND OTHER STRUCTURES," to be as follows:-
The object of our Invention is the preservation of surfaces of iron
or steel liable to the double action of wear and corrosion in sca or
other waters; such surfaces are the iron or steel rudder pins and
gudgeons or braces to receive the rudder pins of screw propellers, and
the pins, eccentrics, and other parts of feathering paddle wheels. Also
the protection from corrosion by sea or other water of the immersed
portions of iron or steel steamships, ships, and vessels, caissons,
pontoons, dooks, harbours, and other such constructions whether fixed
or floating.
In performing the first part of our Invention we attach_to_the_working
parts, or to contiguous surfaces in metallic connection with them, blocks
or pieces of zinc or other metal electro-positive to iron by means of
fastenings, preferably of iron, taking care that a clean surface of the
zinc or other metal shall be forced into intimate contact with a clean
surface of the iron or steel around each fastening, and that such surfaces
and the fastening itself when of metal shall be preserved from contact
with water, whereby the corrosion of the zinc or other metal will be
checked and the block or piece will be held in place till wholly or
almost wholly dissolved. We sometimes make a projection upon the
zinc or other protecting metal fitting into a corresponding depression
in the iron around the fastening, whereby the attachment is made more
secure and dry and clean contact between it and the iron or steel is
more easily attained. These methods of fastening are novel and they
secure greater durability of the protecting substance, but other methods
of fastening may be resorted to.
In performing the second part of our Invention we place zinc or other
suitable protecting metal within and in metallic connection with a
metallic cell or cells either inside or outside the ship or other construc-
tion above or below the water line, and in metallic connection with
the surfaces to be protected, providing means to maintain the cell or
cells full of water when desirable and free water communication with
the water in which the surface or surfaces to be protected may be im-
mersed. We sometimes provide cocks or valves by which communica-
tion with the external water may be cut off when desirable, either to
check the protective action or to facilitate repair of the apparatus or the

page_text: renewal of the protective substance. We prefer to place the protect-
ing metal in the cell or cells in a series of plates or concentric cylinders
or a sheet roll so as to expose a large surface, and to place its junctions
with the iron or steel of the structure out of contact with water, whereby
its corrosion at or near these points will be checked and the desired
metallic connection will be longer preserved. We sometimes employ
an iron plate or plates enclosed in glass or glazed cells, having free
water communication with the external water, the plates being in
efficient electrical communication with the surface protected or with
the protecting substance, so as to afford an indication of the condition
of the immersed portion of the structure as to corrosion, in order that
the protective action may be increased or diminished as required. We
also sometimes make use of these or similar cells for the preservation
from corrosion of rudder pins and gudgeons, screw propeller shafts, and
the working parts of feathering paddle wheels.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said Noel West and Robert Gibson West in the Great
Seal Patent Office on the 29th May 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, NOEL
WEST and ROBERT GIBSON WEST, both of Palace Square, Upper Norwood,
in the County of Surrey, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirtieth day of November, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said Noel West and Robert Gibson West,
Her special licence that we, the said Noel West and Robert Gibson
West, our executors, administrators, and assigns, or such others as we,
the said Noel West and Robert Gibson West, our executors, adminis-
trators, 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 FOR THE
PRESERVATION FROM CORROSION. OF RUDDER PINS AND GUDGEONS OR BRACES,

page_text: SCREW PROPELLER SHAFTS, THE WORKING PARTS OF FEATHERING PADDLE
WHEELS. AND THE SURFACES OF IRON AND STEEL SHIPS, AND OTHER STRUC-
TURES, upon the condition (amongst others) that we, the suid Noel
West and Robert Gibson West, our executors or administrators, by an
instrument in writing under our or their hands and seals. or under
the hand and seal of one of us or them, 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 Robert Gibson West, on behalf
of myself and the said Noel West, 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 state-
ment thereof, that is to say-
The object of our Invention is the preservation of surfaces of iron or
steel liable to the double action of wear and corrosion in sea or other
water; such surfaces in ships are the iron or steel rudder pins and
gudgeons or braces to receive the rudder pins, screw-propeller shafts,
and the pins, excentrics, and other parts of feathering paddle wheels.
Also the protection from corrosion by sea or other water of the immersed
portions of iron or steel steamships, ships, and vessels, caissons, pon-
toons, docks, harbours, and other such constructions, whether fixed or
floating.
In performing the first part of our Invention we attach to the working
parts or to contiguous surfaces in metallic connection with them, blocks
or pieces of zinc or other metal electro-positive to iron, but we prefer
to use zinc, by means of fastenings, preferably of iron, taking care that
a clean surface of the zinc or other metal shall be forced into intimate
contact with a clean surface of the iron or steel around each fastening,
and that such surfaces and the fastening itself when of metal shall be
preserved from contact with water, whereby the corrosion of the zinc
or other metal immediately around the fastening will be checked and
the block or piece will be held in place till wholly or for the most part
dissolved.
One method of accomplishing this is shown in Figures 1, 2, and 3.
Figure 1 shewing a vertical section through the centre of the zinc
unattached, and Figure 2 the same attached to a rudder boss or stern
post boss in a vertical section through the centre of the zinc, and Figure
3 shewing the under side of the piece of zinc in plan. The correspond-

page_text: ing parts in the Figures are similarly lettered. A is a piece of zinc,
which for convenience of manufacture and application we prefer to make
circular. It may be cut out of rolled zinc of suitable thickness and
turned in a lathe or otherwise brought to the required shape, or, as we
prefer, it may be cast in an iron or other mould with a suitable core.
If the castings are not quite smooth and fair it is desirable to make
them so by turning in a lathe or otherwise. A screw bolt, preferably
of iron, is prepared having a taper head to fit the conical countersink
in the zinc, as shewn at B, Figure 2. The rudder boss is prepared by
having a surface of the size of the zinc made flat and smooth by chipping
and filing. A hole is then bored from half an inch to three-quarters of
an inch deep and tapped with a screw to fit that of the bolt; or the hole
may be first drilled and the adjoining surface afterwards made flat with
a cutter. A washer K, Figure 2, of vulcanized india-rubber or similar
material is provided, which may be a quarter or three-eighths of an
inch wide and a quarter of an inch thick, and of the same internal
diameter as the projecting part of the zinc disc or a little larger. For
the protection of the rudder pins and gudgeons of a ship of, say, one
thousand tons register, the pieces of zinc may be from two to two and a
half inches in diameter and from half to three-quarters of an inch thick.
The depression shown at C, Figure 1, should be about an eighth of an
inch deep so that when the whole is screwed in place, as shown at
Figure 2, the washer may be so compressed as to completely exclude
water from the fastening when immersed without preventing the surface
D of the zinc from coming into intimate contact with the iron H of the
rudder pin or boss. In applying the zinc care should be taken that all
the metallic surfaces which come into contact with each other are as
clean and bright as possible, as the preservative power of the zinc
depends on an electrical communication between it and the iron being
secured and maintained, and this communication is greatly impeded by
rust, tarnish, or foreign matters. The bolts and the tapped holes in the
iron should therefore be carefully cleansed from grease and dirt before
use. As however plumbago is a good electrical conductor we sometimes
screw in the bolts with a little of this substance to facilitate their removal
when it is required to renew the zinc. When this is done precautions
should be taken by burring up the head of the bolt or otherwise against.
the bolt "unscrewing." The bolt may be from three to five eighths of
an inch in diameter in the tapped part, and of such a length as not quite
to reach the bottom of the hole into which it is to be screwed, and the

page_text: head should be made with a groove to receive the end of a screwdriver,
or may be made with a short square projection to be screwed home with
a box spanner. When the zinc has been secured in its place the recess
which the head of the bolt forms in the countersink of the zinc should
he filled up with some water-tight cement or packing F, as a mixture of
red and white lead with. japanners gold size, or a plug of hard wood,
ebonite, or similar material may, as is shown at E, Figure 4, be driven
in or screwed into a thread tapped in the zinc which in this case would
have to be made somewhat thicker at this part. The screw for this plug
would be preferably cut the reverse way to that of the iron bolt, or else
with a different pitch to check any tendency of the iron bolt to unscrew.
The plug or screw should be inserted with a water-tight cement. The
cement used in any case should be of such a consistence as not to insinuate
itself between the head of the bolt and the countersink of the zinc. We
sometimes use a water-tight cement or packing instead of the
vulcanized india-rubber washer K, Figure 2, taking care that no part
of it insinuates itself between the surface D of the zinc and the corre
sponding surface of the iron. "We sometimes make the-pieces of zinc with
an inferior projection or stud fitting into a depression in the iron, as
is shown at G, Figure 5, to secure the disc more firmly in its place, and
to prevent the zinc turning with the screw. We also sometimes make
one surface of the zinc concave to fit the convexity of the rudder bosses,
but for convenience and facility of fitting we prefer the above-described
forms. Two or more fastenings may also be used, but for the same
reason one will usually be found preferable. Though a single piece of
zinc might be found to protect adequately both the rudder pin and the
working surface of the fellow boss we prefer to attach separate pieces
to each. We prefer where practicable to apply the zinc as described
above to the end of the rudder pin, as shown in Figure 6, and we some-
times attach a ring of zinc to the under surface of the stern post bosses
secured by two or more fastenings, as above described. This form is
best adapted to holes which have been rebushed, and in this case the
ring of zinc is secured to the under side of the bush. We sometimes
make a projection upon the zinc or other protecting metal fitting into a
corresponding depression in the iron around the fastening, whereby the
attachment is made more secure and dry and clean contact between
the zinc and the iron or steel is more easily attained. These projections
may be either conical, as shewn in section in Figure 7, or preferably of
the form of a short cylinder; with it may be an inferior projection or

page_text: stud, as shewn in section at Figure 8, to prevent the zinc disc turning
round with the bolt, or the same object may be accomplished by making
the bolt eccentric to the cylinder.
In applying our Invention to the preservation of screw shafts, the
working parts of feathering paddle wheels, and other surfaces of iron
or steel liable to the double action of wear and corrosion in sea or other
waters, we prefer to apply the zinc substantially as herein-before
described, taking care that it is attached as close as possible to the
parts to be protected, that it is of such a form as not to present un-
necessary resistance to the water, that it is placed so far as possible out
of the way of mechanical injury, and that the exposed surface of the
zinc bears a sufficient proportion to that of the iron or steel to be pro-
tected. This may vary from one-twentieth or even less to an equal
amount, but we prefer to expose a surface of zinc about one tenth of
that of the iron or steel to be protected.
Figures 9 to 12 represent portions of screw shafts with portions of
their bearings and propellors, and the letter A indicates various situa-
tions in which the zinc or protective metal may be applied according to
circumstances; or it may in some cases be applied in two or more
segments, say 2 to 3 inches wide, and from to inch thick, fitting
closely to the screw shaft and secured by several fastenings, as shewn
in section at Figure 13, where J represents the screw shaft, and Z the
junction of the segments. The remaining letters in this Drawing and
in Figure 14, which represents a full sized section of one of the fasten-
ings, indicate parts corresponding with those similarly lettered in Figures
1 to 8. The vulcanized india-rubber washer K may be or inch thick,
and about inch wide. A groove should be made in the zinc around the
fastening to receive the washer about half the thickness of the washer,
and somewhat wider to allow for the lateral expansion of the washer on
compression, so that when the whole is screwed in place and the head
of the screw cemented over, the surfaces D and H may be brought into
close contact and water be excluded from the fastening.
Figures 15 and 16 represent portions of the floats the adjacent parts
of feathering paddle wheels, and Figures 17 and 18 portions of the
eccentric and adjacent parts of the same, and in all these Figures A
indicates positions in which the zinc or other metal may be applied.
Figure 19 shews a method of attaching the zinc or other metal to
tapered projections on the ends of the joint pins, K, K, being vulcanized

page_text: india-rubber washers on either side of the ring of zinc A, which is made
to fit the tapered projection of the pin; S, an iron washer, and T, the
nut by which the whole is screwed home. -We prefer for the better
and more prolonged protection of the working parts to confine the
action of the zinc to these parts by painting the adjoining parts as usual
(taking care that the zinc itself is not painted) unless these parts are
protected in the manner herein-after described. The thickness of the
zinc affects chiefly its durability, but we prefer not to employ metal of
less. than a quarter of an inch in thickness. Iron or steel valves,
sluices, cocks, pump, buckets, plungers, pistons, piston rods, cylinders
with sliding pistons and screws working in female screws, guides, and
guide blocks the working parts of anchors, and other working parts.
exposed to the action of sea or other-water,-may-be-protected in a similar
way.
1
The methods of fastening above described secure efficient action
and great durability of the protecting substance; the forms described
are also those which. we prefer, but the forms and modes of fastening
are susceptible of some modifications..
In performing the second part of our Invention we place zinc or
other suitable protecting metal electro-positive to iron within and in
metallic communication with a metallic cell or cells, either inside or
outside the ship, above or below the water line, and in metallic connec-
tion with the surfaces to be protected, providing means to maintain the
cell or cells full of water when desirable, and providing free water
communication with the water in which the surface or surfaces to be
protected are immersed. We sometimes provide cocks or valves by
which communication with the external water may be cut off when
desirable, either to check the protective action or to facilitate repair of
the apparatus or the renewal of the protective substance. We prefer to
place the protecting metal in the cell or cells in a series of plates or
concentric cylinders or a sheet roll so as to expose a large surface, and
to place its junctions with the iron or steel of the structure, or with any
iron or steel or other metal to which it may be necessary or desirable
to connect the protective metal, out of contact with water, whereby its
corrosion at or near these points will be checked and the desired metallic
connection will be longer preserved.
'The following is one method of accomplishing this:-We cast zinc
bars, say 11 inches long, 1 inch wide, and of an inch thick, or such

page_text: bars may be cut from rolled zinc; we drill near each end of these bars
in the direction of their thickness and through the bars holes of an
inch in diameter, so that the outside of these holes shall be half an
inch from the ends of the bars. We also cast a number of zinc plates,
say of an inch in thickness, and 27 inches long by 10 inches wide,
with three or four equidistant holes, as in Figure 20, the holes being
of such a size that the zinc bars can be passed through them freely; or
the plates may be cut out of rolled zinc, and the holes afterwards made
by punching and filing or otherwise, taking care that when the plates
are superposed the holes are exactly opposite to each other. The margins
of the holes should be, as shown, 1 inch from the edges of the plates.
Then, having filed shallow notches in the zinc bars to receive the zinc
plates, the outside surfaces of the two outside plates being when in
place of an inch from the margin of the holes drilled in the bars, we
support the bars suitably, so that one of the bars may pass through
each of the holes. We then pass the first plate on to the three or four
bars, placing it as above indicated, and soldering it into its place; the
second plate is then passed on and soldered, and so on till twelve or
thirteen plates have been soldered on, with an interval of about of
an inch between each plate and the next. To facilitate the soldering
and to give greater strength to the whole one or more strips of zinc may
be soldered across the bottom of the series of plates parallel to the zinc
bars. It is desirable that the surfaces to be soldered should be made
bright; and we prefer in all cases where zinc or other protective metal
has to be soldered for the purposes named in this Specification to select
as far as possible those solders which while possessing the necessary
fusibility and strength have the feeblest galvanic relations with the
protective metal. We provide also a water-tight tank 2 feet 6 inches
long by 1 foot wide and 1. foot deep, inside measurements, which if of
iron, as we prefer, may either be cast or made from boiler plate,
rivetted to angle-iron corners with an outside angle iron rivetted round
the top to form a flange on which to bolt the cover, the said flange being
pierced with a sufficient number of holes to admit of the cover, which is
to be provided with corresponding holes, being bolted to it securely and
water-tight. The cover we prefer to have cast half an inch thick with
paps or projections on the inside surface to which the zinc bars are to be
bolted, the "paps" being about 1 inch in diameter and projecting
about 1 inch from the surface of the cover.
And the cover may be
advantageously thickened an inch on the outside over the paps and

page_text: the margin which is to be bolted to the flange of the tank. The cover
may be further strengthened by one to more "feathers," say to an
inch thick, and standing 2 to 3 inches high in the middle. The "paps"
are to be so placed on the tank cover that their centres will come
opposite the centres of the holes in the zinc bars when the system of
zinc plates and bars is placed centrally on the cover. The "paps" are
to have holes drilled through them, and the cover perpendicular to
the plane of the cover. Turned bolts about 3 inches long between
the under side of the head and the nut when the latter is screwed home
(preferably with hexagon heads and nuts) with the under surface of the
head made bright, and vulcanized india-rubber washers with an internal
diameter of about three-eighths of an inch and an external diameter of
inch and a quarter of an inch thick-are-provided. It is desirable
that the bolts should accurately fit the holes in the zinc bars and the
cover paps. The upper surface of the cover is made bright around
these holes, and also round several of the holes by means of which it is to
be bolted to the flange. These preparations being made the zinc plates
and bars are bolted to the tank cover through the holes in the bars and
"paps," as shown in the full-sized Drawing, Figure 21, which is a
portion of a perpendicular transverse section taken through the centre
of one of the bars and the side and cover of the tank when all is fitted
in place. L is the zinc bar, and M the outside zinc plate soldered in its
place, as above described; N is the cover of the tank with one of its
projecting paps P; Q is the screw bolt; R. R, are two of the india-
rubber washers above described placed above and below the zinc bar;
S is a thin iron washer interposed between the lower india-rubber washer
and the nut T; U is the side of the cell or tank with its outside angle
iron V, to which the cover N is bolted water-tight with the interposition
of a washer or packing X by means of the screw bolt and nut W; Y is
a band of sheet iron which may be 2 inches wide and about 1/2" thick,
through which a hole has been punched, cut, or drilled, and which is
secured to the cover of the cell by the bolt Q in the manner shown in
the Drawing. This band should be brightened on both sides at the
ends, and should be sufficiently long to admit of being bolted to some
part of the ship's skin or framing. The object of this band is to secure
more direct and efficient electrical communication between the zinc
and the hull of the vessel, but it is not essential provided that efficient
electrical communication be established through the body of the cell.
We prefer after securing bright metallic contact between the band Y and

page_text: the bolt and cover N to protect these bright surfaces from the
oxidizing influences of the atmosphere by means of paint or cement,
taking care that the paint or cement does not insinuate itself between
the contact surfaces. We take similar precautions with reference to
such of the bolts and nuts W as we brighten to obtain metallic com-
munication between the cover and the body of the tank or cell. We
establish a communication between the interior of the tank or cell and
the external water by means of one or preferably two pipes, preferably
of cast iron, which in a cell of the size described may be of 1 inch to
2 inches internal diameter, suitable holes for the attachment of the pipes
having been made in the sides, top, or bottom of the tank or cell. We
prefer to place these pipes at or near the ends of the cell, one at or
We sometimes
near the top and the other at or near the bottom.
furnish these pipes with cocks, by which the communication with the
external water may be partially or entirely cut off. The part of the
ship's skin to which the pipe is attached may be pierced with a number
of small holes, instead of with a single hole of the diameter of the pipe,
or any other suitable contrivance may be adopted to prevent the entrance
of weeds, small fish, or other solid substances, retaining as large a total
perforated area as possible. There is an air hole in the cover capable of
being closed by a small tap or plug. The cell may be placed in any
convenient part of the ship below the water line, but it is desirable,
both for efficiency of action and that it may be out of the way of
mechanical injury and not interfere with the stowage of cargo, to place
it near to the ship's side; and we prefer to place it at the turn of the
bilge, supporting it on a sufficiently strong, say inch, iron shelf, to
which it should be bolted by means of lugs rivetted to the cell, so that
the pitching and rolling of the vessel may not bring any strain on the
pipes or their attachments. The shelf may be rivetted or bolted to
inch iron plate suitably secured to the
brackets or knee plates of
frames of the ship.
The
Figures 22 and 23 show the method of attachment described.
cell may also be placed above the water line, provided that-it can be
maintained full of water and with a free water communication with the
external water, but this method is chiefly applicable to vessels engaged
in river or lake navigation, and is not equally well adapted for sea-going
vessels. The points to be specially attended to in the fitting up of these
cells are that there shall be efficient electrical communication between
the zinc and the skin of the ship, that the cell shall be capable of being

page_text: maintained full of water, and that there shall be free water communica-
tion between the interior of the cell and the external water. The zinc or
other metal may be applied in various forms besides that above described.
The plates, for example, with connecting bars or plate or plates may be
cast in one piece and secured to the cover of the cell, either by some
such arrangements as that we have described, or by fastenings similar to
those described in a former part of this Specification or otherwise. 1t
is desirable, however, that water should be excluded from the surfaces
of contact of the zinc and iron. The zinc may also be attached to the
ends, bottom, or sides of the cell, but we prefer attaching it to the top,
both for convenience of original fitting and to facilitate repairs and
renewals. The cells may be made of such sizes and shapes as may De
found convenient, but we-prefer-distributing the zinc required for the
protection from corrosion of a given ship-in several cells placed about
equidistant from each other and arranged alternately on opposite sides
of the vessel to the use of a smaller number of larger cells. We prefer
to expose to the action of the water an area of zinc about one-fiftieth of
that-of-the iron or steel to be protected, but we do not confine ourselves
to this proportion as a larger relative surface of zinc may be exposed,
while on the other hand more or less complete protection will be
afforded by a smaller proportion of exposed zinc. For the protection of
a ship of 1,000 tons register we recommend the use of four such cells
as we have described. We sometimes build the cell into the vessel or
other structure to be protected between the floor plates, or in any othe
convenient situation, or we attach it to the sides or other portion of the
structure, with or without the intervention of pipes. In thus applying the
cell we may attach the zinc or other protecting metal as before described
to the top or any other convenient part of the cell, taking care to ensure
electrical communication between the zinc or other metal and the
iron or steel surfaces to be protected, and we prefer to exclude water
from all contact surfaces on which such electrical communication
partially or entirely depends, so that efficient communication may be the
longer preserved. We provide a free water communication between
the interior of the cell and the external water which may or may not be
provided with cocks, sluices, or valves to regulate or cut off altogether
this water communication; and we prefer to protect the cocks, sluices,
or valves, and the cells from the entry of weeds, small fish, or other
solid bodies by some contrivance similar to that already described.
We sometimes employ an iron or steel plate or plates enclosed in a

page_text: glass or glazed or partially glazed cell or cells having free water com-
munication with the external water, the plates being in efficient electrical
communication with the surface protected or with the protecting
substance so as to afford an indication of the condition of the immersed
portion of the structure as to. corrosion, in order that the protective
action may be increased or diminished as required. These indicating
cells, which are preferably closed at the top and water-tight, may be
placed where most convenient so long as the water in them covers the
iron or steel plate or plates and free water communication with the
external water is at the same time maintained. We prefer, however, in
adapting them to iron or steel ships to place them near the sides of the
vessel, and if two or more are employed to arrange them alternately on
opposite sides of the ship and about equidistant from each other. If
two indicating cells only are employed, we prefer to place them, say,
about one quarter of the ship's length from the stem and the stern
respectively. We prefer to construct the cells of thick plate glass
cemented into iron frames, which should be either painted or otherwise
protected from corrosion, and to encase them suitably, so that they may
be protected from fracture or injury. We secure in each of these
cells a plate or plates of iron or steel of the same description as the
protected surfaces. These plates may, if more convenient, be made a
part of the structure of the cell or cells, the only essential conditions
being that they shall be immersed in the water of the cell in electrical
communication with the protected surfaces and capable of being
inspected. We prefer in adapting the cells to ships to maintain the
cells only partially full of water, either by placing them about the
level of the water line or by including a portion of air in the cell, so
that by the motion of the vessel combined with that of a current of
water through the cell the indicating plate or plates may be subjected
to the friction of water. Any connection that it may be necessary to
make within the cell to establish electrical communication between the
indicating plate and the protected surfaces will be preferably made with
iron or steel only, and it is advisable to exclude water from the contact
surfaces by some such means as have been described in former parts of
this Specification. A pipe or pipes are adapted to form a water
communication between the interior of the cell and the external water.
These pipes may be 1 inch to 1 inch in bore and may be advantageously
adapted (if two are employed) to the opposite ends of the cell, and it is
desirable to guard against the entrance of weeds, small fish, or other

page_text: solid substances by the contrivance already named or otherwise. The
pipes may be provided with cocks by means of which communication
with the external water may be cut off when desired. It is preferred to
have an air hole in the cover with a small cock adapted to it, so that if
the apparatus be placed below the water line any air which may
accumulate in the vessel may from time to time be allowed to escape.
The cells may be conveniently made 2 feet long, by 6 to 8 inches wide,
and 1 foot deep, and maintained about two-thirds full of water; one or
more sides may be made of plate glass " or ¼ inch thick. We also
sometimes make use of cells contaming zine or other metal electro-
positive to iron, similar to those herein-before described for the
-preservation from corrosion of rudder pins and gudgeons, or braces to
receive the rudder pins, screw propeller shafts, -the-pins, eccentrics,
and other working parts of feathering paddle wheels, and other surfaces
of iron or steel liable to the double action of wear and corrosion in sea
or other water. For these purposes we construct the cells substantially
as herein-before described and apply them similarly, placing them as
near as convenient to the surfaces to be protected, and taking care that
there is-efficient electrical communication between the protecting metal
and the surfaces to be protected, and that there is free water com-
munication between the interior of the cell and the water in which the
surfaces to be protected are immersed. When the bulk of the
immersed iron or steel in metallic communication with these surfaces
is not protected by the means herein-before described, we prefer to paint
the surfaces adjoining the working surfaces, and to expose a surface of
zinc or other metal electro-positive to iron equal to about one tenth of
that of the iron or steel surfaces to be protected.
Having now described the nature of our Invention, and the manner
in which the same may be performed, we wish it to be understood that
what we claim is,-
First. The preservation from corrosion by the double action of
mechanical friction and exposure to sea or other water of rudder pins
and gudgeons, or braces, screw propellor shafts, the working parts of
feathering paddle wheels, and other surfaces exposed to such influences
in ships and other structures by the application, substantially as herein
described, of zinc or other metal electro-positive to iron.
Secondly. The protection from corrosion by sea or other water of the
immersed or occasionally immersed portions of iron or steel steamships,

page_text: ships, and vessels, barges, caissons, pontoons, docks, harbours, and other
constructions, also of iron or steel rudder pins and gudgeons or braces
to receive the rudder pins, screw propellor, screw propellor shafts and
their bearings, the pins, eccentrics, and other parts of feathering paddle
wheels, and other surfaces of iron or steel liable to corrosion in sen or
other water by means of zinc or other metal electro-positive to iron
contained in and in metallic connection with metallic cells which are in
metallic connection with the surfaces to be protected, and which have
free water communication between their interior and the water in which
the surfaces to be protected are immersed.
Thirdly. The use of cocks, valves, or sluices as described to cut off
or partially cut off communication between the interior of the cells and
the external water when desired, either to check the protective action, or
to facilitate repair of the apparatus, or the renewal of the protective
substances.
Fourthly. The use of an iron or steel plate or plates enclosed in a.
glass or glazed or partially glazed cell or cells, or forming a part of
such cells, having free communication with the water in which the
protected surfaces are immersed, the plate or plates being in efficient
electrical communication with the surface protected, so as to afford an
indication of the condition of the immersed portion of the structure as
to corrosion in order that the protective action may be increased or
diminished as required.
In witness whereof, I, the said Robert Gibson West, have hereunto
set my hand and seal. this Twenty-fifth day of May, in the year
of our Lord One thousand eight hundred and sixty-nine.