IMPROVEMENTS IN DISCHARGING MUD OR 'SPOIL' FROM DREDGERS AND OTHER VESSELS
Year: 1875

page_text: LETTERS PATENT to Frederic Eliot Duckham, of Millwall Docks, in
.the County of Middlesex, for the Invention of "IMPROVEMENTS IN
DISCHARGING MUD OR 'SPOIL' FROM DREDGERS AND OTHER VESSELS."
PROVISIONAL SPECIFICATION left by the said Frederic Eliot
Duckham at the Office of the Commissioners of Patents, with his
Petition, on the 18th December 1875.
I, FREDERIC ELIOT DUCKHAM, of Millwall Docks, in the County of
Middlesex, do hereby declare the nature of the said Invention for "Im-
PROVEMENTS IN DISCHARGING MUD OR 'SPOIL' FROM DREDGERS AND OTHER
VESSELS," to be as follows:-
My Invention relates to an improved method of discharging, the mud
or "spoil" raised by dredging from the dredgers or barge in which it is
received, and the Invention consists in the employment for the purpose
of pneumatic pressure applied in the manner and by the means herein.
after described;

page_text: According to my Invention the mud or "spoil" is received from the
dredging buckets in tanks capable of being closed air-tight. These
tanks are preferably in the hold of the dredger itself, or they may be in
a separate barge, and when full (the dredger or barge having been con-
veyed to a suitable position near the shore or otherwise) the receiving
apertures are closed and the tanks made air-tight with the exception of
an inlet at top for compressed air, and an outlet at bottom for the mud
or spoil. Compressed air is then admitted to the tank above the
mud which is expelled through the outlet at bottom, and conveyed by
suitable pipes or hose to the shore or elsewhere, where it is dicharged in
any convenient place."
I obtain the compressed air from an air pump preferably directly con-
nected with and of a power equalling the main engine of the dredger.
To prevent the choking of the pipes a screen or grating is provided
through which the mud or spoil passes before it enters the outlet
pipe.
I prefer to make the tanks of a form favoring the flow of the mud or
spoil to the outlet, and when necessary employ scrapers, agitators,
injection of water or air, in such a manner as to assist the discharge.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Frederic Eliot Duckham in the Great Seal Patent
Office on the 14th June 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FREDERIC
ELIOT DUCKHAM, of Millwall Docks, in the County of Middlesex, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of December, in the
year of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Frederic Eliot Duckham, Her
special licence that I, the said Frederic Eliot Duckham, my executors,
administrators, and assigns, or such others as I, the said Frederic Eliot
Duckham, my executors, administrators, and assigns, should at any

page_text: "
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 DISCHARGING MUD OR SPOIL' FROM DREDGERS
AND OTHER VESSELS," upon the condition (amongst others) that 1, the
said Frederick Eliot Duckham, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and
seals, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Frederick Eliot Duckham, do
hereby declare the nature of my said Invention, and in what manner
the same is to be performed, to be particularly described and ascer-
tained in and by the following statement, reference being had to the
accompanying Sheet of Drawings, and to the letters and figures marked
thereon, that is to say :-
My Invention relates to an improved method of discharging from
dredgers or barges the mud and "spoil" raised from the bottoms of
rivers, harbours, docks, canals, and other similar places, and the Inven-
tion consists in the employment for the purpose of pneumatic pressure
applied as hereafter described.
According to my Invention the mud or "spoil" is received from the
dredging apparatus in a tank or tanks capable of being closed air-tight.
These tanks are preferably in the hold of the dredger itself, or they may
be in a separate barge, and when full the dredger or barge having been
conveyed to a suitable position near the shore or otherwise the receiving
apertures are closed and the tanks made air-tight with the exception of
an inlet or inlets for compressed air, and an outlet or outlets for the
mud or spoil. Compressed air is then admitted to the tank to expel the
mud which is conveyed by suitable pipes or hose to the shore or
elsewhere.

page_text: To prevent the choking of the pipes a screen or grating is provided
through which the mud or "spoil" passes before it enters the outlet
pipe.
I prefer to construct the tanks of a form favoring the flow of the
mud or "spoil" to the outlet, and in order to prevent a deposit of mud
in the tank so thick that it would not run freely to the outlet and would
therefore remain in the tank, I prefer to inject compressed air (with or
without an admixture of water) supplied by force pump or other means
through a number of nozzles at the bottom of the tank, said nozzles
being pointed towards the outlet. By this means the particles are
' prevented from settling, and are kept in suspension until the whole is
expelled from the tank. Compressed air may moreover be admitted
into the discharge pipe with the same object.
In order that my Invention may be more readily understood, I have
illustrated it in the accompanying Drawings, in which Figure 1 repre-
sents a longitudinal section of a steam dredger; Figure 2 is a midship
section of the dredger in the act of discharging the mud.
.
.
A, A, are the tanks to receive the mud, of which there are preferably
two, one at either side of the central well B in which the chain of
buckets or scoops C works. The mud raised by the latter is conveyed
by shoots to the tanks as usual. The tanks are preferably of the form
shown, and are made of sufficient strength to sustain the pressure
required to discharge the mud. When the tanks are full the vessel or
barge containing them is moved to its place of discharge near the shore
or in other convenient position, as in Figure 2. The apertures beneath
the shoots having been closed by proper covers, there is attached to the
outlet pipe E a discharge pipe or hose F by which the mud is conveyed
to the shore. If the mud is contained in two tanks the two outlets may
unite in a single outlet pipe E, as shown, in which case sluice valves are
provided in the branches at G so that should one tank be emptied before
the other the outlet from such tank can be closed. H, Figure 1, is the
pipe through which air is forced into the tank by an air pump I worked
by the same engines that drive the buckets and the screw propeller;
K, K, represent the engine cylinders.
admitted at the upper part of the
In addition to the compressed air
tanks to press upon the surface of the mud for the purpose of expelling
the same, compressed air may also be admitted through nozzles at the

page_text: bottom of the tank (with or without an admixture of water, as before
mentioned) to keep the mud agitated and prevent any thick deposit in
the tank. I may provide mechanical agitators or scrapers in the tank
for the purpose.
If found desirable I may employ a reservoir for compressed air on
board or on shore, and admit the air therefrom into the tanks or pipes
in any manner to facilitate the discharge.
The Invention may also be similarly employed for discharging mud
from tanks not fitted in the dredger itself but in a separate barge, a
suitable air pump operated by steam or other power being provided on
board or on shore or a connection made with the tanks in the barge, and
the air pump on board another barge or vessel.
Having described the nature of my Invention, and the manner of
performing the same, I declare that what I claim as my Invention to be
protected by the herein-before in part recited Letters Patent is, the
application and employment of pneumatic pressure, as herein described
and illustrated, for discharging the mud or spoil raised by dredging from
tanks, whether such pneumatic pressure be used alone or in combination
with an injection of compressed air or of water through nozzles at the
bottom of the tank, or with mechanical agitators or scrapers, as set
forth.
In witness whereof, I, the said Frederic Eliot Duckham, have
hereunto set my hand and seal, this Thirteenth day of June, in
the wear of our Lord. One thousand eight hundred and seventy.
FRED. E. DUCKHAM. (L.S.)