IMPROVEMENTS IN COFFERDAMB, AND IN APPARATUS FOR PLACING THE
Year: 1871

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, Patent Agent, for the Invention of
"IMPROVEMENTS IN COFFERDAMB, AND IN APPARATUS FOR PLACING THE
."-A communication from abroad by John Edward Walsh, of
the City, County, and State of New York, United States of
America.
SAME.
Sealed the 14th July 1871, and dated the 11th May 1871.
COMPLETE SPECIFICATION filed by the said Alexander Melville Clark
at the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 11th May 1871, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
5
COMPLETE SPECIFICATION filed by the said Alexander Melville Clark
at the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 11th May 1871, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent, send greeting.

page_text: petitioned Her Majesty to grant unto me, my executors, administrators,
and assigns, Her Royal Letters Patent for the same, and have made
solemn declaration that it has been communicated to me from abroad
by John Edward Walsh, of the City, County, and State of New York,
United States of America.
.
NOW KNOW YE, that I, the said Alexander Melville Clark, do hereby
declare that the following Complete Specification under my hand and
seal, fully describes and ascertains the nature of the said Invention, and
in what manner the same is to be performed, in and by the following
statement, reference being had to the two Sheets of Drawings hereunto
annexed, and to the letters and figures. marked thereon (that is to
say) :—
The object of this Invention is to furnish a better and more secure
cofferdam in which piers or other structures are built under and below
the surface of water, that can be easily moved and sunk in its place,
and be as easily removed when desired, and that shall be water-tight;
and to so construct a cofferdam that a continuous wall of masonry may
be built and the cofferdam moved along in advance of the wall as it is
built and afford all the necessary or needed protection that the ordinary
cofferdam could while masonry is being built within it, and to furnish
an apparatus for the convenient placing and moving the dams; and it
consists in the construction of some of the parts of the shell that form
the cofferdam, and in the structure as a whole, and in the construction of
the walls of the dam, so that after one section of what is to be a con-
tinuous wall is built within the cofferdam the dam can then be moved
forward in the line at which the wall is to be built, and by devices be
clamped fast to the wall that is completed so that another section of wall
of the length of the inside of the dam can be built and joined upon
that first constructed; and in the employment within the dam of loose
piles, said piles and the dam being constructed so that the piles act as
guides to the dam in raising and lowering it.

page_text: is a side view of the dam; Figure 6 is a top view of the dam and section
of a wall after the dam has been advanced for building a second section
of the wall; Figure 7 represents a plan, and Figure 8 a vertical section
taken, as indicated by the irregular line x, x, in Figure 7 of the improved
cofferdam and apparatus for placing the same.
In Figures 1, 2, and 3, A represents the walls of the cofferdam, con-
structed from metal plates a of any convenient size and shape, which are
joined together by riveting the plates to upright braces b. Braces b
arc each strengthened in a lateral direction by having a flange b¹ project
centrally of its width a sufficient distance to give the required strength
to resist the external pressure. The side walls are curved so that the
transverse diameter is considerably greater in the centre of the length of
the side walls than at their extreme ends. This curvature is retained in
the side walls by means of the screw or hook rods c, c, that extend longi-
tudinally the entire length of the side walls and are made fast at their
ends to inwardly projecting lugs c¹, c¹, which are secured in the side walls
near their shoulders or extreme ends, and by such curvature the side
walls will resist a much greater external pressure than if made straight
as is usually the case. The space between the side walls A and the
rods c may be occupied by a series of air and water tight compartments
to enable the dam to be floated where desired. B, B, are inwardly curved
swinging doors hung to the shoulders of the side walls by hinges d'in
such manner that the doors shall swing outwardly. At the hinged joint
between the doors B and the side walls A, and on the inside thereof are
angle irons & formed to fit on one angle of the curvature on the side
walls and on the other the inward curvature of the doors. Between the
angle irons & and the side walls A on one side and the doors on the
other is interposed rubber packing d¹. In order to strengthen the doors B
bent metal plates C are bolted fast to their inner sides, as seen in Figure 1
at 0,
and extending inwardly at an angle from a direct line until they
nearly meet when the doors are closed; they are then bent to conform
to a line drawn from between the extreme outer ends of the doors at one
end to that of the other, and go parallel with each other to a short
distance of the outer ends of said doors where they terminate, but are not
made fast at their outer ends to the sides of the curved doors. At the
outer or abutting edge of the doors rubber packing d is interposed,
which packing is equal or about equal in thickness to the two plates C

page_text: at their outer ends. Near the outer edges of the doors is a sufficient
number of screw bolt holes e to hold them in firm contact when desired
by means of the screw bolts and nuts f¹ that pass through the door
plates and rubber packing, compressing the packing to a joint that
will exclude the water, and also compress the loose outer ends of bent
plates C together the whole length of their parallel sides, and form by
this means a kind of flexible supporting braces to the doors.
For the convenience of lowering the cofferdam, or the one half of it,
into the position it is to occupy in building a pier or excavating the
foundation of a pier, or for any other purpose where a cofferdam would
be used, suspending rings D are inserted through the metal walls and
braces, into which the suspending devices can be attached or hooked,
and the structure raised or lowered as the case may be. When the
cofferdam is lowered into its proper place it is necessary to secure it in
such position and guard against it being moved out of such place by
strong currents in the water, or by other causes.
This is accomplished
by firmly bolting or otherwise securing T shaped braces h upon the side
walls, which may be made of metal or other sufficiently strong and
proper material, and having a sliding pile H, longer than the height of
the side walls with a groove in one of its sides that will fit over the
T brace and freely slide vertically thereon, which is driven down into
the ground below the bottom of the cofferdam, and securely holding it
in place.
By constructing the cofferdam in the form herein-described and shewn
the pressure of the water upon its walls has the tendency and does act
to compress the parts together and keep the joints close, thus materially
strengthening the structure as a whole when in and surrounded by water,
consequently a cofferdam can be constructed of thinner plates, have less
weight, and costing less in the aggregate than if having parallel sides
on right lines.
In the dam represented in Figures 4, 5, and 6, the improvements
relate to the construction of the rear wall of the dam, and its adaptability
to be attached to the wall when built, the other parts of the dam being
constructed as described with reference to Figures 1, 2, and 3.
In Figures 4, 5, and 6, A represents the curved side walls of the dam,
which may be of any required length or height; B is the rear or back
end wall extending from each side towards the centre of the width of

page_text: the dam, but leaving a space O in the centre a little wider than the
wall to be built is thick, and which for the purpose of greater strength,
is made double and with compartments B¹. At the inner sides of the
two inner compartments the inner wall plate C, on each side of the
centre, turns a right angle and forms the inside walls to the two interior
compartments, next the open space O, and extends back and in the rear of
the wall B so as to form a flange C', of sufficient width to be clamped
against the wall when necessary. To the extreme back edge of flange C¹
are hinged curved doors a, and at the junction of the doors with the
flanges, and attached to the doors are angle plates c, with packing d
interposed between the plate and door and between the plate and flange
plate C', so that when the doors are closed against the packing d between
them at their extreme rear ends, and bolted together as seen in Figure 4,
all the joints will be water-tight. The rear or double wall B is hinged
to the side walls A, and the joints where so hinged are made water-
tight in the same manner by angle plates and packing. The compart-
ments B', may or may not have bottoms, as fancy or want may dictate.
The doors a at the rear end of the dam are hinged in such way that they
can be raised off of their hinges, and be detached from the flanges C¹.
The operation of building a wall by the use of this cofferdam is as
follows: The cofferdam as seen in Figure 4, is taken to the precise
spot where the wall is to be built, sunk, and secured in its position in
the usual way, the water pumped out and the foundation prepared, then
the wall D is built as seen in said Figure 4, the entire length of the
inside of the dam, this done the doors a are removed from the flanges C¹.
The cofferdam is then moved forward and planted as seen in Figure 6,
with the forward end of the wall between the flanges C¹. As the wall D is
being built there are anchored and built in the wall metal eyes or staples E,
and extending the proper distance from cach side of the wall, and at a
suitable distance from the forward end of said wall as seen in Figure 4, to
receive the bottom ends of the clamp piles F. Between the flanges C₁
and the wall D is placed a thick packing sheet d, when the clamp
piles Fare forced at their bottom or lower ends into the eyes or staples E
brought towards each other at their top ends and bearing hard against
the flanges C¹, their entire length, when the clamp f, having the two
eyes is placed around them, and securely holds the cofferdam water-
tight upon the wall, when the water is again taken out of the dam, and

page_text: continue the successive changes until the desired length of wall is
completed. Curved walls, or walls with angles can be built with this
construction of dam as well as straight ones. The double walls B being
hinged to the side walls, they can when necessary be opened, which will
allow of the successful turning of the dam where angles or curves are
built in the wall, and may facilitate the handling and moving the dam
at other times. Such construction of cofferdam has long been needed
and will be a valuable acquisition wherever sea or continuous walls are
to be built.
In Figures 7 and 8, A represents the cofferdam, and B, B, the appa-
ratus or floating derricks used for placing the dam. The dam A consists
structure, the walls
of an oblong or other suitably shaped chamber or
of which may be solid, and that is opened at top and bottom, but one or
more of the ends of which is made to open and close to facilitate the
removal of the dam from the work it is employed on, or placing of it
about an abutment or pier under water. Said ends are hinged to tho
sides of the dam as at b, b, forming half doors c, c, which have their
front edges bent to form flanges d, d, that receive in between them
packing strips e, and are bolted together to make a close joint. These
doors are made close at their hinges by angle iron braces f, f, secured
firmly to either door, and holding between them and the door india-
rubber or other safe and flexible packing strips 9, 9, arranged to bear
against the interior surfaces of the sides of the dam when the doors
are closed. By this construction the joint is free from disturbance or
being broken at the hinges when opening and closing the dam; C, C, are
fixed piles secured to the sides and ends of the dam to effect the
nccessary hold or imbedding of it in the bed of the stream when lower-
ing it to its place, and said dam is further held and steadied, also guiding
in raising and lowering it by means of loose piles D, D, arranged to fit
as slides down grooved boxcs E, E, attached to the inside of the dam.
These piles D, D, are first driven into the bed of the river or stream,
and then the dam lowered down them as guides, and after the work is
completed, slid up over them, said piles afterward cither being allowed
to remain to give stability to the foundation, or being removed as desired.
Such employment and construction of loose piles largely facilitates the
placing of the dam.

page_text: The apparatus for placing the dam consists of derricks arranged in
tiers or sets along either side of the dam on floating bases or scows con-
stituting floating derricks B, B, which are provided with any suitable
tackle and mechanism for raising and lowering the dam by attachment
of the falls h, h, of the derricks thereto. To ballast these floating
derricks as against side tip by the dam in raising and lowering it I
construct either a scow or floating base i, i, with a ballast chamber G,
along its back or outer side. The ballast for the purpose may be varied,
but when water is used then it will be advisable to provide cach
chamber G with one or more valves k for letting in water as required,
and that when not needed may afterwards be pumped out.
I am aware that metal has been used in the construction of coffer-
dams, and I lay no claim to its use, I am also aware that doors or gates,
and their joints packed with a flexible substance are in use, and I do
not broadly claim these, but what I do claim as the Invention, and
desire to secure by Letters Patent is,―
1st. The bent plates C bolted at one end only to the inwardly curved
doors B, in the manner and for the purpose shown.
2ndly. The angle iron & and packing du in combination with the
inwardly curved hinged doors B having flexible bent plates C interposed
packing du, bolts f, and nuts f', all constructed and arranged to operate
in the manner described.
3rdly. The cofferdam herein-described, composed of the outwardly
curved side walls A strengthened by rods c, inwardly curved hinged
doors B, having the flexible bent metal plates C, packing d" and d¹¹,
and angle irons d', all the parts constructed and arranged together in
the manner and for the purpose shown.
4thly. The cofferdam herein-described having a double wall B at its
rear end with openings O, flanges C', and removable doors a constructed
and arranged in the manner and for the purpose set forth.
5thly. The flanges C₁ of the cofferdam herein described, in combi-
nation with the interposed packing d, metal eyes or staples E, clamp
piles F, and clamp f, constructed and arranged in the manner and for'
the purpose
described.

page_text: 6thly. The combination of: the loose piles D, D, constructed to act as
guides, with the boxes E, E, and shell or walls of the dam, essentially
as described.
In witness whereof, I, the said Alexander Melville Clark, have
hereunto set my hand and seal, this Tenth day of May, in the
year of our Lord one thousand eight hundred and seventy-one.
Witness,
W. CLARK,
53, Chancery Lane,
London.
A. M. CLARK. (L.S.)