Improvements in Scouring and Removing Sand or Mud from Tidal Stream and River Beds, Bars, or Submerged Banks, and Apparatus Employed therefor.
Year: 1886

page_text: Date of Application, 24th Nov., 1886.
Complete Left, 23rd Aug., 1887.
Complete Accepted, 23rd Sept., 1887.
Improvements in Scouring and Removing Sand or Mud from Tidal
Stream and River Beds, Bars, or Submerged Banks, and
Apparatus Employed therefor.
1 NATHANAEL ROBERT GRIFFITH, of Westminster Chambers, Wrexham, in the
County of Denbigh, Mining Engineer do hereby declare the nature of my said
invention to be as follows:-
According to my Invention, I use compressed air for scouring and removing sand,
or mud from tidal stream and river beds bars, or submerged banks; the compressed
air is distributed in an extended line over the surface of the bed, bar, or bank to be
scoured, or removed and is directed so as to impinge on the sand, or mud in such a
manner as to disturb and throw the sand, or mud into mechanical suspension in the
water to such an extent and in such an upward direction that the so suspended sand,
or mud can be carried away by the tide, or stream.
To effect the distribution of the air as above described I preferably employ an
articulated duct, or flexible pipe in which are a number of reservoirs for compressed
air which is supplied to the duct, or pipe from an air compressing engine of any
suitable kind. The pipe, or duct is provided with suitable orifices for the escape of
the compressed air and is laid upon or drawn over the bed, bar, or bank to be
removed so that the compressed air as it escapes from the orifices of the reservoirs
impinges on and throws up the sand, or mud.
As an example of operation the flexible duct is moored at one end in such a manner
that it can be swept over the surface to be removed the other end being attached to a
steam tug which contains the air compressing machinery and which draws the
apparatus over the surface to be removed and so that the compressed air impinges on
such surface and throws up the sand or mud so that it can be carried away by the
tide, or stream.
A convenient form of flexible duct for carrying my Invention into practice may
consist of a series of metal pipes provided with nozzles so arranged that the sand, or
mud when disturbed will be driven in an upward direction by the force of the
compressed air. These pipes, or reservoirs are connected together by short lengths

page_text: of hose pipe, or other flexible connection of smaller diameter. This flexible duct is
fastened to and carried by a wire rope, or other hawser, one end of which is moored
to the surface to be removed and the other end is carried up to and fastened to a
steam tug. This end of the duct being connected to a compressed air reservoir in
connection with air compressing machinery on the steam tug. The submerged end
of the flexible duct is carried up to the surface, or water level and closed by a loaded
valve so that the water can be blown through the duct when starting the apparatus.
In working, the strain on the flexible duct is borne by the wire rope, or other hawser,
and the weight of the duct is mostly supported by the buoyancy of the air filled pipes,
or reservoirs, so that the duct does not sink into the sand, or mud, but lays on and is
drawn by the steam tug so as to sweep over the surface to be removed. The force of
the compressed air issuing from the nozzles disturbing the sand, or mud so that it is
carried away (while in mechanical suspension) by the tide, or stream.
Instead of mooring the duct it can be dragged by the steam tug over the surface to
be removed. In this case 1 attach the duct to a boom instead of a hawser.
Dated this 23rd November 1886.

page_text: Improvements in Scouring and Removing Sand or Mud from Tidal
Stream and River Beds, Bars, or Submerged Banks, and
Apparatus Employed therefor.
[, NATHANAEL ROBERT GRIFFITH, of Westminster Chambers, Wrexham, in the
County of Denbigh, Mining Engineer, do hereby declare the nature of my said
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
According to my Invention I use compressed air for scouring and removing sand,
or mud from tidal stream and river beds, bars, or submerged banks; the compressed
air is distributed in an extended line over the surface of the bed, bar, or bank to be
scoured, or removed and is directed so as to impinge on the sand, or mud in such a
manner as to disturb and throw the sand, or mud into mechanical suspension in the
water to such an extent and in such an upward direction that the suspended sand, or
mud can be carried away by the tide, or stream.
To effect the distribution of the air as above described I preferably employ an
articulated duct, or flexible pipe in which are a number of reservoirs for compressed
air which is supplied to the duct, or pipe from an air compressing engine of any
suitable kind. The pipe, or duct is provided with suitable orifices for the escape of
the compressed air and is laid upon, or drawn over the bed, bar, or bank to be
removed so that the compressed air as it escapes from the orifices of the reservoirs
impinges on and throws up the sand, or mud.
As an example of operation the flexible duct is moored at one end in such a
manner that it can be swept over the surface to be removed, the other end being
attached to a steam tug which contains the air compressing machinery and which
draws the apparatus over the surface to be removed and so that the compressed air
impinges on such surface and throws up the sand, or mud so that it can be carried
away by the tide, or stream.
A convenient form of flexible duct for carrying my Invention into practice may
consist of a series of metal pipes provided with orifices, or nozzles so arranged
that the sand, or mud when disturbed will be driven in an upward direction by
the force of the compressed air. These pipes, or reservoirs are connected together
by short lengths of hose pipe, or other flexible connection of smaller diameter.
This flexible duct is fastened to and carried by a wire rope, or other hawser, one end
of which is moored to the surface to be removed and the other end is carried up to
and fastened to a steam tug. This end of the duct being connected to a compressed
air reservoir in connection with air compressing machinery on the steam tug.
The other end of the flexible duct is carried up to the surface, or water level
and closed by a loaded valve so that the water can be blown through the duct
when starting the apparatus. In working, the strain on the flexible duct is borne
by the wire rope, or other hawser and the weight of the duct is mostly supported

page_text: by the buoyancy of the air filled pipes, or reservoirs, so that the duct does not sink
into the sand, or mud, but lays on and is drawn by the steam tug so as to
sweep over the surface to be removed. The force of the compressed air issuing
from the orifices, or nozzles disturbing the sand, or mud so that it is carried
away (while in mechanical suspension) by the tide, or stream.
Instead of mooring the duct it can be dragged by the steam tug over the surface
to be removed. In this case I attach the duct to a boom instead of a hawser.
In order that my Invention may be clearly understood I have hereunto annexed
four sheets of Drawings which are marked with letters and figures of reference
corresponding with those, used in the following explanation, like letters and figures
being used to denote the same, or corresponding parts throughout the various views
and figures.
In the carrying out of my Invention the flexible air duct may be arranged to be
swept or drawn, or placed over the surface to be removed in various ways. For
example it may be arranged in the manner shown at Figure 1 of the annexed
Drawings in side elevation and at Figure 2 in plan, in which a is the flexible, duct.
The end a¹ of this flexible duct a is fastened to the moored floating buoy b and the
other end a² is led on board a "
tug" con which there is suitable air compressing
machinery to which the end a³ of the duct a is connected. The duct a is of length to
allow it to sweep the surface to be acted upon in manner such as shown in the
Drawings. The end a¹ of the duct a is provided with a stop cock, or loaded outlet
valve which may be of any known construction. The duct a consists of a series of
metal pipes a³ each pipe being about 12 inches in diameter and 9 feet in length, but
these dimensions will of course vary according to the quantity and pressure of the air
used and other circumstances such as the nature of the surface to be removed, the
locality, and the power of the tug. These metal pipes a³ are connected together by
short lengths of piping a'. These connecting pipes at may for example be of hose
pipe. The ends of the metal pipes a³ are closed except where the connecting pipes a
enter them. The metal pipes a³ extend only along that portion of the duct a which
will lay on the surface to be acted upon. The underside of the pipes a³ is provided
with small orifices through which jets of compressed air are discharged from the duct
onto the surface to be removed to throw the sand or mud into suspension so that it
will be carried away by the current. The orifices in the pipes a³ may be simple holes,
or they may be provided with nozzles. The number and size of the orifices depends
upon the quantity and pressure of air used, for example the orifices may be of an
inch in diameter and about 16 inches apart and the pressure of air 20 pounds on the
square inch above the atmospheric pressure and the pressure due to the head of water.
The area of the orifices and the connecting pipes a should be so proportioned relatively
to one another that the pressure of the air at the orifices shall be equal, or approxi-
mately equal throughout the apparatus. The rising ends a of the duct a are of
flexible tube only. "The whole duct is securely fastened to and carried by a hawser d
one end of which is fastened to the buoy b and the other end to the tug c which
moves the duct about over the surface to be removed, or instead of the buoy beach
end of the duct a may be attached to a tug, so that the two tugs will drag the duct a
over the surface to be removed.
In the example of my Invention shown at Figure 3 in side elevation and Figure 4
in end elevation, the pipes a are attached to boom e and a duct a is led from the
centre of the duct a to the tug c and to the air compressing machinery. Towing
hawsers d are led from the tug and fastened to the ends of the boom e as well as to
the centre.
In the example of my Invention shown at Figure 5 in plan and Figure 6 in side
elevation, the pipes a³ are arranged to drag from the boom e after the manner of a
harrow the extreme ends of the pipes a being closed and the pipes being connected
by the chains which are provided to keep the pipes a in position and also by the
flexible couplings a and by the distance links, or pieces d². This form of apparatus
is very suitable for keeping clear of sand, or mud the entrance to docks, or harbours.
For this purpose the apparatus is placed in the position where it is to be used and

page_text: compressed air driven through it and a current of water obtained by letting water
out of the dock which will take away the sand, or mud driven into suspension by the
action of the air. The apparatus may in this case be stationary, or drawn across the
part to be acted upon.
In the example shown at Figure 7 in plan and Figure 8 in side elevation, the
duct a, which is shown broken off, is of considerable length and is towed endways
forwards and backwards along the surface to be acted upon.
Instead of moving the duct a by a tug as above described, it may be moved by
other means such as by a locomotive, or a stationary engine on the land, working the
duct by suitable rope, or equivalent connections.
Having now particularly described and ascertained the nature of my said Invention
and in what manner the same is to be performed I declare that what I claim is :—
First. The method herein described of scouring and removing sand, or mud from
tidal stream and river beds, bars, or submerged banks, which method consists in the
employment of jets of compressed air placed, or moved over and caused to impinge
upon the surface to be removed so that the silt, or other matter will be driven into
suspension in the water so as to be carried away by the stream, or current,
substantially as set forth.
Second. The apparatus for scouring and removing sand, or mud from tidal stream
and river beds, bars, or submerged banks, consisting of a flexible air duct, such as a
constructed arranged and operated substantially as set forth and as described with
reference to Figures 1 and 2 of the Drawings.
Third. The apparatus for scouring and removing sand, or mnd from tidal stream
and river beds, bars, or submerged banks, consisting of an air duct, such as a
constructed arranged and operated substantially as set forth and as described with
reference to Figures 3 and 4 of the Drawings.
Fourth. The apparatus for scouring and removing sand, or mud from tidal stream
and river beds, bars, or submerged banks, consisting of a flexible air duct such as a
constructed and operated substantially as set forth and as described with reference to
Figures 5 and 6 of the Drawings.
Fifth. The apparatus for scouring and removing sand or mud from tidal stream
and river beds, bars, or submerged banks, consisting of a flexible air duct, such as a
constructed arranged and operated substantially as set forth and as described with
reference to Figures 7 and 8 of the Drawings.
Dated this 22nd der of Anomat 1887