IMPROVE- MENTS IN DREDGERS
Year: 1875

page_text: LETTERS PATENT to William Duff Bruce, Vice Chairman and
Engineer-in-Chief to the Port Commissioners of Calcutta, Bengal,
India, at present of No. 5, Ladbroke Square, Notting Hill, in the
County of Middlesex, and William Fothergil Batho, Civil Engineer,
of Victoria Chambers, Westminster, for the Invention of "IMPROVE-
MENTS IN DREDGERS."
Sealed the 2nd June 1876, and dated the 6th December 1875.
PROVISIONAL SPECIFICATION left by the said William Duff Bruce
and William Fothergil Batho at the Office of the Commissioners
of Patents, with their Petition, on the 6th December 1875.
We, WILLIAM DUFF BRUCE, Vice Chairman and Engineer-in-Chief
to the Port Commissioners of Calcutta, Bengal, India, at present of
No. 5, Ladbroke Square, Notting Hill, in the County of Middlesex, and
WILLIAM FOTHERGIL BATHO, Civil Engineer, of Victoria Chambers,
Westminster, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN DREDGERS," to be as follows :-
:―
This Invention relates to an improved dredger for the purpose of

page_text: excavating and deepening channels, canals, rivers, docks, basins, or
other similar work, in which excavators are arranged so as to work in
wells placed diagonally across the vessel, and in such positions that the
maximum width of the channel excavated is equal to the sum of the
diameters of the excavators employed, whereby the material to be
excavated is removed in a wider channel than in the case of an ordinary
dredger.
For excavating I prefer to use the excavators described in the Speci-
fication of Letters Patent granted to the said William Fothergil Batho,
dated 19th May 1873, No. 1809.
The operation of raising and lowering, as well as of opening and
closing the spades of the excavators, is performed by crab winches or
other contrivance arranged so as to act either simultaneously or
independently, the necessary movements being effected by friction gear
operating on chain barrels.
Each excavator is provided with a swinging discharging shoot working
automatically therewith, and drawn into position by a chain fitted to a
barrel riding loose on a shaft, and actuated by a friction clutch. Upon
releasing the shoot at the end of a stroke it swings back upon a chain
and between guides, and is tipped by its own weight.
By the use of bow and stern crabs driven by friction gear the advance
of the dredger for each lift of the excavators is regulated automatically.
In cases where the bed of the river, canal, or other similar channels is
of much harder substance than it is possible to cut through by ordinary
dredging the above arrangement of vessel may be still retained, and
instead of working the excavators by means of chains hydraulic rams are
to be applied to the centre rods of the excavators for closing the spades
or lifting, and also to the sliding collars for opening the spades and for
lowering or forcing and holding down the excavators.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Duff Bruce and William Fothergil Batho
in the Great Seal Patent Office on the 5th June 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, WILLIAM
Duff Bruce, Vice Chairman and Engineer-in-Chief to the Port Com-
missioners of Calcutta, Bengal, India, at present of 5, Ladbroke Square,
Notting Hill, in the County of Middlesex, and WILLIAM FOTHERGIL
BATHO, Civil Engineer, of Victoria Chambers, Westminster, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixth 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 successors,
give and grant unto us, the said William Duff Bruce and William
Fothergil Batho, Her special licence that we, the said William Duff
Bruce and William Fothergil Batho, our executors, administrators,
and assigns, or such others as we, the said William Duff Bruce and
William Fothergil Batho, our 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 DREDGERS," upon the con-
dition (amongst others) that we, the said William Duff Bruce and
William Fothergil Batho, our executors or administrators, by an instru-
ment in writing under our, or their, or one of our or 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 we, the said William Duff Bruce and
William Fothergil Batho, do hereby declare the nature of our said
Invention, and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following state-

page_text: ment and accompanying eight Sheets of Drawings, reference being had
to the figures and letters marked thereon, that is to say :-
This Invention relates to an improved dredger for the purpose of
excavating and deepening channels, canals, rivers, docks, basins, or
other similar work in which excavators are arranged, so as to work in
wells placed diagonally or otherwise across the vessel, and in such
positions that the maximum width of the channel excavated is equal to
the sum of the diameters of the excavators employed, or the excavators
are suspended from the ends of jibs capable of swinging round, so as to
produce a like result, whereby the material to be excavated is removed
in a wider and deeper channel than in the case of an ordinary dredger.
The operation of raising and lowering as well as of opening and
closing the spades of the excavators is performed by crab winches or
other suitable means arranged so as to act either simultaneously or
independently, the necessary movements being effected by friction gear
operating on chain barrels.
Each excavator is provided with a swinging discharging shoot working
automatically therewith, and drawn into position by a chain fitted to a
barrel riding loose on a shaft, and actuated by a friction clutch. Upon
releasing the shoot at the end of a stroke it swings back upon a chain
and between guides, and is tipped by its own weight.
In cases where the bed of the river, canal, or other similar channel
is of much harder substance than it is possible to cut through by
ordinary dredging the above arrangement of vessel may be still retained,
and instead of working the excavators by means of cranes hydraulic 1
rams may be applied to the centre rods of excavators for closing the
spades or lifting, and also to the sliding collars for opening the spades
and for lowering or forcing and holding down the excavators.
The scales to which the annexed Drawings are made are marked
thereon, and the figures and letters of reference on each separate Sheet
indicate the same parts throughout the Sheets to which such reference is
made.
Sheet No. 1 represents a longitudinal sectional elevation; Sheet No. 2,
a plan; and Sheet No. 3, a cross section of an improved dredger for
excavating and deepening channels, canals, rivers, docks, basins, or
other similar work in which excavators are arranged, so as to work in

page_text: wells placed diagonally or otherwise across the vessel, and in such
positions that the maximum width of the channels excavated is equal to
about the sum of the diameter of the excavators employed, whereby the
material to be excavated is removed in a wider and deeper channel than
in the case of an ordinary dredger.
For dredging we prefer to use the excavators described in the Speci-
fication of Letters Patent, dated 19th May 1873, No. 1809, granted to
me the said William Fothergil Batho, and communicated from abroad
by me the said William Duff Bruce.
Referring to Sheets Nos. 1, 2, and 3 we shall now proceed to describe
the construction of the above dredger.
A represents the hull made of iron or other suitable material for
supporting the machinery, and within which are built wells a, a¹, a³,
through which the excavators B, B³, B³, descend when open to the bed
of the channel to be excavated. The excavators B, B', B2, are suspended
by chains or wire ropes b, 61, 62, 63, 64, 65, actuated by winches C, C¹, C²,
placed in some convenient position in the hull. The chains 6 to 6°
pass over pullies attached to staging D fixed at such a height above the
deck as to allow of swinging shoots E, E¹, E', passing beneath the
excavators B, B³, B³, into which the material is discharged. The
shoots E, E', E, are suspended from the staging by chains (d), and
move between guides e in such a manner that they are moved and
tipped by their own weight, as shown in dotted lines on Sheet No. 3.
On the excavators being raised the shoots can be drawn under them
by means of chains passing over pullies g, and actuated by a friction
drum driven by gearing from the main shafting i, and are thus
worked automatically with the excavators.
Having now described the construction of the various parts for
effecting the excavating or dredging by means of excavators actuated by
chains, we shall now proceed to describe the means of putting these
parts into operation when required.
In some convenient position within the hull A are placed winches
C, C, C³, constructed in such a manner as to fulfill the required
motion of the excavators specified in the Letters Patent, No. 1809, A.D.
1873, above referred to, which we prefer to use; the ropes or chains 6
to attached to the central rod and sliding collar are passed over

page_text: drums fitted to the winches O, O', C³, running loose on the shafts, and
each provided with brakes. The drums on the winches C, C¹, C³, are
of sufficient diameter to allow of a certain length of rope or chain being
wound round the one, and unwound on the other before blocks placed
on their inner sides impinge on each other, and both drums revolve
together either to raise or lower the excavators B, B¹, B³.
Before lifting, friction clutches keyed on the shafts have to be put in
gear with the drums and the winch set in motion; thus, supposing the
excavators to have been just lifted, charged with mud or other material,
the shoots are drawn into position under them by chains fattached
to barrels driven by friction gear. The drums on the winches C,
C', C³, holding the chains b, b², 6*, attached to the sliding collars of the.
excavators are now held stationary by means of brakes, and the
excavators B, B1, B2, open, discharging their contents into the shoots E,
E, E, under them. The shoots are then drawn from under the
excavators, and in their turn discharge their contents.
The excavators B, B¹, B³, are allowed to descend immediately the
shoots E, E¹, E*, are tipped and the operation is repeated.
In Sheet No. 4, a different mode of arranging the excavators B, B¹, is
shown, and they are suspended from the ends of jibs D at the bow and
stern of the barge or vessel, so that by the swinging round of the jibs
the channel to be excavated is rendered wider and deeper. The Drawing,
Sheet 4, also shows a different mode of discharging the material into a
swinging shoot E brought under the excavator, or removed on one side
as required.
The excavator B is lifted in a similar manner to that described
previously by means of a winch C, and the shoot E is allowed to swing
under it and receive its contents; the material raised may be, as most
convenient, either discharged into suitable barges moored alongside, or
in cases where the channel is too narrow to admit of them, the material
raised may be discharged into one or more cylinders F, and blown out
by compressed air over the banks, as shewn in Sheet No. 4, Fig. 3, and
in the manner described in Letters Patent, granted to F. Duckham,
and dated 10th July A.D. 1875, No. 2491.
In cases where the soil is very stiff hydraulic pressure can be applied
to the spades of the excavators, as shewn in Drawings Nos. 5, 6, 7,

page_text: while the central rod remains stationary, thereby opening the spades,
and discharging their contents into the shoots E, E¹, below. The water
pressure is then released from the whole of the cylinders H, H³, H³, H³,
and the excavator B can descend by its own weight, allowing the shoots
E, E¹, which are drawn back by counterweights W, W¹, to discharge
their contents either into barges or cylindrical vessels F, F', as shewn, to
be dealt with in the manner described in the Specification of the Letters
Patent of F. Duckham, No. 2491, A.D. 1875, above referred to, or
otherwise. On the excavators B reaching the bed of the channel to be
operated upon pressure is given under the rams h, h³, in the cylinders
H, H', and above the pistons h2, h3, in the cylinders H2, H3, causing the
excavators B to penetrate into the material; the operation, as described
before, can then be repeated.
Sheet No. 7, Fig. 1, shows a part plan; Fig. 2, a cross section; and
Fig. 3, a part longitudinal section.
Sheet 8, Fig. 1, an elevation taken diagonally; and Fig. 2, a part plan
of an alternative method of working the excavators by hydraulic
pressure.
A represents the hull similar to those shewn on Sheets 1, 2, 3, 5, and
6, and described previously; F, F', are cylindrical vessels for holding
the excavated material to be disposed of in manner described in the
Specification of the Patent of F. Duckham, before referred to, or other-
wise; D are wrought-iron stanchions forming staging to support a
hydraulic cylinder H, within which are two pistons, the rod of the one
working inside the rod of the other h', the inner one acting as the
central rod, and the outer one in connection with the sliding collar
of the excavator. The inner piston rod h works on a tube 7, which
forms a water connection between the two pistons h, h¹. To the staging
hangs a bar P, from which are suspended counterweights W, W¹, and to
which chains & passing over pullies q are attached to the extremities of
shoots E, E¹, hinged at their other ends, the counterweights W, W¹,
on the bar P being sufficiently heavy to draw the shoots E, E¹, up into
the position shewn on Sheet 7, Fig. 2. K are angle irons, against which
the shoots E, E¹, rest when in position to receive the discharge of the
excavator B, as shown in dotted lines, Figure 1, Sheet 7.
Having now described the construction of the dredger, as shewn in
Sheets 7 and 8, we will now proceed to describe the means of putting

page_text: the several parts into operation at the various periods when they are
required.
Sheet 7, Fig. 2, shews a sectional elevation of a dredger with the
excavator described in Letters Patent, No. 1809, A.D. 1873, before
referred to.
Water pressure is now taken through the tube in the inner piston h,
and escapes by means of holes in the inner piston rod / into the space
between the two pistons h, h¹, and a movement upwards of the piston /
connected with the central rod takes place, while the piston h¹ in con-
nection with the sliding collar moves downwards. This action forces the
spades of the excavator B into the material to be operated upon, and
closes them, and it is then ready to be raised. The water is shut in
between the two pistons h, h¹, and pressure given to the under side of
the lower piston ¹ when the whole is raised. In rising the sliding collar
impinges on the bar P, and allows the shoots E, E³, to fall into position
by their own weight, as shewn in dotted lines on Sheet 7, Fig. 2. The
water communication between the two pistons h, h¹, is now open, and
pressure applied on the upper side of the upper piston h in connection
with the central rod of the excavator B, thereby opening the spades
and discharging their contents into the shoots E, E', which form
channels to the cylindrical vessels F, F¹, or to the barges, as may be
preferred. The water below the lower piston ¹ is now released, and the
excavator B can again descend to the bed of the river or channel.
Having now described the nature and particulars of our said Inven-
tion, we desire it to be understood that we do not claim the mechanical
parts of which the machinery herein described is composed, as taken
separately or apart from the combination and application thereof, in
manner and for the purposes herein described, nor do we claim the con-
struction and arrangement of the hydraulic machinery, as described for
excavating in a hard material; but what we do claim is, constructing a
dredger, substantially as herein described, wherein a series of excavators
are arranged so as to work through wells placed diagonally, or other-
wise, across a vessel, or are placed at the bow and stern thereof, and are
capable of sweeping through an arc, so as in every case to widen or
render deeper the channel excavated, and having shoots suspended,
as described, for convenience of working, and for the ready disposal of
the material. For dredging unusually hard material the excavators can,

page_text: if desired, be worked by hydraulic power, as herein described and shown
in the Drawings.
In witness whereof, I, the said William Fothergil Batho, for and
on behalf of myself and the said William Duff Bruce, have here-
unto set my hand and seal, this Second day of June, One 5
thousand eight hundred and seventy-six.