Improvements in and relating to Dredging Machines.
Year: 1889

page_text: Date of Application, 31st July, 1889
Complete Specification Left, 21st Nov., 1889-Accepted, 21st Dec.,
1889
Improvements in and relating to Dredging Machines.
I, EDWARD ALEXANDER VON SCHMIDT, of Barkly Street, St. Kilda, Melbourne,
in the Colony of Victoria, Civil Engineer, do hereby declare the nature of this
invention to be as follows:-
This invention of improvements in and relating to dredging machines has been
devised for the purpose of providing a simpler yet more efficient and economical
dredger than those that are at present in use.
My invention relates to that class of dredging machine wherein a rotary cutter or
excavator is employed to loosen the sand, clay, silt or other material which is then
removed by the action of a centrifugal pump and is finally discharged through a
suitable arrangement of tubes at any desired spot.
In this type of dredging machine, the main suction pipe, that is the one which
conveys the semi-liquid material from the rotary cutter or excavator to the pump, has
usually been adapted to be moved from side to side of an oblong shaped hull or scow
around the end thereof, which was made semi-circular in plan in order to admit of
this movement, but I have found in practice that the weight of the revolving cutter
and suction pipe together with their various raising, lowering, adjusting and operating
gear caused the hull or scow of the dredger to heel over, the effect being that a
deeper cut was taken when these devices were shifted to the side of the hull than
when they were arranged centrally thus entailing either a very undesirable amount of
labour in order to adjust the depth of cut or else producing an irregular surface or
finish to the work. I am enabled to obviate these disadvantages by constructing the
hull of the dredger in a circular form capable of being secured in position by a
vertical mooring spud or pile passing centrally therethrough, or in any other
convenient manner. Upon this circular hull I arrange a suitably shaped framing
through which, and clear of the said hull, passes a second mooring spud or pile. This
framing partially supports one end of the discharge tube and is provided on its
underside with wheels or rollers arranged to run in a circular track on the deck of the
hull or scow whilst a toothed pinion driven by suitable gearing also carried by said
platform gears with a rack which is arranged concentrically with said circular track
in order that the hull of the dredger may be caused to rotate bodily under the said
fixed frame.
Owing to the number and variety of joints that were required in the suction pipe
and the difficulty of maintaining them in an efficient condition so as to prevent air
from entering and interfering with the working of the pump I lave devised certain
improvements whereby I am enabled to simplify the construction and reduce the
number of these joints whilst at the same time I secure sundry other material
advantages.
In a dredging machine constructed according to my invention the discharge pipe
passes from the periphery of the centrifugal pump up through the deck at about the
centre thereof whilst the suction pipe leads from the centre of said pump out to the
rotary cutter or excavator which is situated at the side of the hull opposite to
the discharge tube and fixed supporting platform. A telescopic joint as well as a ball
joint are provided in the length of discharge pipe leading from the pump to the side
of the dredger hull, the purpose being to allow said pipe to regulate itself to its
varying position as the hull is rotated in adjusting the cut of the excavator to the
right or left.
Whenever it has been found necessary or desirable to support the discharge pipes
of dredgers upon pontoons the usual practice hitherto has been to provide but one
joint in each length of pipe between these pontoons the result was that owing to their

page_text: not having sufficient freedom to rise and fall with the waves they only lasted a very
short time on account of the amount of wear and tear entailed by its arrangement.
Now, according to one portion of my present invention 1 provide for the construction
of each length of pipe between the pontoons with a pair of ball joints which are
preferably constructed as hereafter described and are so arranged that the pontoons
can rise and fall with perfect freedom thereby obviating the injurious effects that as
above stated arise from the system of coupling at present in vogue.
I have also devised certain improvements in rotary cutters for dredging machines
which consist in forming them as will hereinafter be particularly described so that
when fitted with a slightly modified form of knife they may if required be employed
for cutting above the water line and these cutters are so constructed that they cut
under the material thus greatly facilitating its removal.
61
33
66
My invention also comprises certain improvements in centrifugal pumps whereby I
am.enabled to provide a more efficient pump than has hitherto been in use and one
moreover that is free from certain objections that have heretofore been incidental to
the employment of this class of pump for dredging purposes. One important feature
in centrifugal pumps constructed according to my invention is that their vanes are so
shaped and arranged that their outer ends are approximately radial from the centre
or axis of the pump runner whilst the inner portions of these vanes are inclined so
that if produced they would be about tangential to a small circle described from said
centre or axis, thus forming a vane having a forward curve in contradistinction to a
rearward one as has hitherto been the general practice in constructing pumps of this
class. These two portions are connected by a suitable curve thus producing a vane
having good holding or propelling powers and but very little tendency to slip."
With a vane of this construction also there is but little danger of a piece of rock
becoming jammed between it and the side of the opening leading to the discharge.
Further improvements which are comprised in this portion of my invention consist in
constructing and arranging the various parts of a centrifugal pump for dredging
purposes as will hereinafter be described so that a passage is provided therethrough
which is free from any corners or sharp curves wherein pieces of rock or the like
could find a lodgement. I provide the stuffing box through which the main shaft of
the pump passes with a constant supply of water either led directly thereto or else
contained in a casing or box outside said stuffing box. By this means I am enabled
not only to maintain a perfectly air-tight joint but also to keep the bearing entirely
free from grit or other injurious substances.
According to my invention the circular dredger hull is adapted to be secured in its
working position by means of a vertical mooring spud or pile which passes centrally
therethrough. A framing is provided which is supported by wheels or rollers running
in a circular way on the deck of the hull and this framing is adapted to support the
discharge tube and is provided with a pinion gearing with the said circular rack
which is arranged upon the deck of the hull concentrically with the said circular way.
A winch is also supported on this framing and may be employed to impart motion to
a pinion in order to rotate the circular hull bodily so as to adjust the cut of the
excavator or rotary cutter to the right or left as desired. This winch has a winding
drum around which are passed lifting chains for adjusting the cutter. It is driven by
a pair of suitable cylinders and a clutch is provided upon the shaft of the winding
drum in order that it may be thrown out of gear when it is desired to drive the hull
adjusting pinion which is likewise arranged to be thrown into or out of gear with the
winch when desired by means of a suitable lever. A band brake is provided on one
end of the winding drum in order to facilitate or regulate the working of the winch.
The herein before mentioned frame is secured in position by a second mooring spud or
pile. Alongside each of the two spuds above mentioned vertical masts are provided
which are firmly secured to the herein before mentioned fixed framing and are each
provided with suitable lifting tackle whereby the two spuds may readily be raised
when desired. For this purpose lifting chains are passed over pullies on the masts
and are secured at their ends to eye-bolts passing through the upper portions of the
said mooring spuds.

page_text: The discharge tube leads from the periphery of the centrifugal pump up through
the deck of the dredger hull and thence over the framing to any desired spot. This
pipe passes through the deck as near to the central mooring spud as is practicable the
bject being to reduce the deviation and elongation of the discharge tube as much as
possible when the dredger hull is rotated. In order that this said tube may adjust
itself to the varying positions of the hull as compared with the hereinbefore
mentioned fixed platform or framing I provide it with a telescopic joint as well as
with a ball joint.
I prefer to support this discharge tube upon the fixed frame by a step bearing
carried by a pendant bracket bolted to said frame and I provide it with a stuffing box
and gland in order that it may readily turn in any desired direction. This device for
supporting the discharge tube may also be employed with the ordinary style of
dredger it being only necessary to bolt the step bearing and the strap around the
stuffing box to the side of the hull instead of to the fixed frame. A suction tube leads
from the rotary cutter or excavator and is supported partly by an extension which is
journalled in a bearing carried on a framing secured to the hull of the dredger; and
partly by being connected with the other portion of said pipe by a suitable ball joint.
To about the centre of the vertical portion of this suction tube are attached chains
passing over winches and adapted either to raise or lower it or to cause it to swing
up sideways in order to lift its end clear of the water so that in the event of it
becoming choked up with clay or the like it can be raised into such a position that
the clay may be removed by hand. In order however to prevent as far as possible
this choking of the suction tube, I provide a vacuum gauge whereby the consistency
of the material being carried up said tube will be indicated in order that steps may be
taken to reduce such consistency if necessary by raising the excavator into clear
water.
I prefer to construct the pair of ball joints that I provide in the discharge tube
between each length of pipe that is carried on the pontoons with a ring which is
adapted to fit over the male end and to be bolted to a flange on the female end. A
packing groove being formed thereby which is adapted to receive packing whereby a
simple yet efficient joint will be provided. I couple the pontoons to each other by
chains or their equivalents secured to pins in each corner of the pontoons so that by
slacking out the chain on the one side and hauling on to the chain on the other side
the inclination of the pontoons one to the other may be altered so that in a long line
of them they will describe any desired curve whereby the discharge pipe may be led
to any required spot. It will be obvious also that the said pontoons will be free to
rise and fall with the waves in perfect freedom owing to the pair of ball joints which is
provided in the length of tube between the said pontoons. The rotary cutter herein-
before mentioned consists of a circular frame or wheel to whose rim are bolted knives
or cutters having their lower ends turned either outwardly or inwardly in order
to cut under the material being excavated thus greatly facilitating its removal. It
will be obvious to all persons skilled in the art to which my invention relates that by
slightly modifying the construction of these cutters they might be arranged either
vertically or radially from the rim of the circular frame in order to adapt, them to
varying descriptions of work. For instance when arranged vertically the excavation
might be employed for cutting material above the water line it being only necessary
to keep the end of the suction pipe below.
In order to construct a more efficient centrifugal pump for dredging purposes than
has hitherto been in use I form the side plates of the runner so that they curve down
from the vertical and incline towards the centre of the suction pipe. Upon the end
of the driving shaft of the pump, I bolt a dividing cone and the whole is so arranged
that a clear passage which is free from corners or sharp curves is provided there-
through from the suction to the delivery pipe. The vanes of the runner I construct
so that the inner ends thereof shall incline so that if produced they would form
tangents to a small circle described around the centre or axis of the runner whilst
their outer ends are approximately radial therefrom and these two ends are. connected
by a forward curve as shewn. which is approximately an arc of a circle thus completing

page_text: a vane having as herein before stated great "holding" or propelling powers and but
little tendency to slip.
A tube is provided leading to the stuffing box of the pump driving shaft from a
cistern holding a supply of water at a sufficient "head" to cause a flow through said
stuffing box and into the pump thus tending to keep said stuffing box always air
tight and free from grit or other foreign material. Instead of thus conveying the
water to the bearing I sometimes enclose the whole of the stuffing box in a case or
jacket which may either be filled with water from time to time or may when provided
with a cover be supplied with water under pressure through a pipe leading from a
cistern of water in a similar manner to that just described.
Dated this Thirtieth day of July 1889.
CRUIKSHANK & FAIRWEATHER,
62, Saint Vincent Street, Glasgow, Agents.
COMPLETE SPECIFICATION.
Improvements in and relating to Dredging Machines,
I, EDWARD ALEXANDER VON SCHMIDT, of Barkly Street, St. Kilda, Melbourne, in
the Colony of Victoria, Civil Engineer, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
This Invention of improvements in and relating to dredging machines has been
devised for the purpose of providing a simpler yet more efficient and economical
dredger than those that are at present in use.
My invention relates to that class of dredging machine wherein a rotary cutter or
excavator is employed to loosen the sand, clay, silt or other material which is then
removed by the action of a centrifugal pump and is finally discharged through a
suitable arrangement of tubes at any desired spot.
In this type of dredging machine the main suction pipe, that is the one which
conveys the semi-liquid material from the rotary cutter or excavator to the pump,
has usually been adapted to be moved from side to side of an oblong shaped hull
or scow around the end thereof, which was made semi-circular in plan in order to
admit of this movement, but I have found in practice that the weight of the revolving
cutter and suction pipe together with their various raising, lowering, adjusting and
operating gear caused the hull or scow of the dredger to heel over, the effect being
that a deeper cut was taken when these devices were shifted to the side of the hull
than when they were arranged centrally thus entailing either a very undesirable
amount of labour in order to adjust the depth of cut or else producing an irregular
surface or finish to the work. I am enabled to obviate these disadvantages by con-
structing the hull of the dredger in a circular form capable of being secured in
position by a vertical mooring spud or pile passing centrally therethrough, or in any
other convenient manner. Upon this circular hull I arrange a suitably shaped
framing through which and clear of the said hull, passes a second mooring spud or
pile. This framing partially supports one end of the discharge tube and is provided
on its underside with wheels or rollers arranged to run in a circular track on the
deck of the hull or scow whilst a toothed pinion driven by suitable gearing also
carried by the said platform gears with a rack which is arranged concentrically with
said circular track in order that the hull of the dredger may be caused to rotate
bodily under the said fixed frame.
Owing to the number and variety of joints that were required in the suction pipe
and the difficulty of maintaining them in an efficient condition so as to prevent air
from entering and interfering with the working of the pump I have devised certain
improvements whereby I am enabled to simplify the construction and reduce the
number of these joints whilst at the same time I secure sundry other material
advantages.
In a dredging machine constructed according to my invention the disharge pipe

page_text: passes from the periphery of the centrifugal pump up through the deck at about the
centre thereof whilst the suction pipe leads from the centre of said pump out to the
rotary cutter or excavator which is situated at the side of the hull opposite to the
discharge tube and fixed supporting platform. A telescopic joint as well as a ball
joint are provided in the length of discharge pipe leading from the pump to the side
of the dredger hull, the purpose being to allow said pipe to regulate itself to its
varying position as the hull is rotated in adjusting the cut of the excavator to the
right or left.
Whenever it has been found necessary or desirable to support the discharge pipes
of dredgers upon pontoons the usual practice hitherto has been to provide but one
joint in each length of pipe between these pontoons the result was that owing to their
not having sufficient freedom to rise and fall with the waves they only lasted a very
short time on account of the amount of wear and tear entailed by this arrangement.
Now, according to one portion of my present invention I provide for the construc-
tion of each length of pipe between the pontoons with a pair of ball joints which
are preferably constructed as hereinafter described and are so arranged that the
pontoons can rise and fall with prefect freedom thereby obviating the injurious
effects that as above stated arise from the system of coupling at present in vogue.
I have also devised certain improvements in rotary cutters for dredging machines
which consist in forming them as will hereinafter be particularly described so that
when fitted with a slightly modified form of knife they may if required be employed
for cutting above the water line and these cutters are so constructed that they cut
under the material thus greatly facilitating its removal.
64
My invention also comprises certain improvements in centrifugal pumps whereby I
am enabled to provide a more efficient pump than has hitherto been in use and one
moreover that is free from certain objections that have heretofore been incidental to
the employment of this class of pump for dredging purposes. One important feature
in centrifugal pumps constructed according to my invention is that their vanes are
so shaped and arranged that their outer ends are approximately radial from the centre
or axis of the pump runner whilst the inner portions of these vanes are inclined so
that if produced they would be about tangential to a small circle described from said
centre or axis, thus forming a vane having a forward curve in contradistinction to
a rearward one as has hitherto been the general practice in constructing pumps of
this class. These two portions are connected by a suitable curve thus producing a
vane having good holding or propelling powers and but very little tendency to
'slip." With a vane of this construction also there is but little danger of a piece
of rock becoming jammed between it and the side of the opening leading to the
discharge. Further improvements which are comprised in this portion of my inven-
tion consists in constructing and arranging the various parts of a centrifugal pump for
dredging purposes as will hereinafter be described so that a passage is provided
therethrough which is free from any corners or sharp curves wherein pieces of rock
or the like would find a lodgement. I provide the stuffing box through which the
main shaft of the pump passes with a constant supply of water either led directly
thereto or else contained in a casing or box outside said stuffing box. By this means
I am enabled not only to maintain a perfectly air-tight joint but also to keep the
bearing entirely free from grit or other injurious substances.
My invention, moreover, comprises sundry other improvements which are hereinafter
described.
I will now proceed to more particularly describe and ascertain the nature of my
invention and in what manner the same is to be performed by reference to the
accompanying drawings in which:
Figure 1 is a plan.
Figure 2 a side elevation, and
Figure 3 a front elevation of a dredging machine constructed according to
invention.
my
Figures 4 and 5 are respectively a side and an end elevation of the upper portion

page_text: of the vertical part and of the outer portion of the horizontal part of the suction
These
pipe of my dredging machine illustrating the manner of supporting the same.
Figures, moreover, illustrate the application of a vacuum gauge to said suction pipe
for the purpose hereinafter described.
Figures 6 and 7 are respectively a side elevation partly in section and a plan of a
portion of the discharge pipe of my dredging machine illustrating the manner of
supporting same on the fixed platform thereof.
1
Figures 6 and 7° are similar views to Figures 6 and 7 but illustrating my method
of supporting discharge pipes applied to a dredger of ordinary construction.
Figure 8 is a plan, and
Figure 9 a side elevation illustrating my system of coupling up various lengths of
pipe when supported on pontoons.
Figure 10 is a vertical transverse section on line a, a, Figure 9 but drawn to a
larger scale.
Figure 11 is a longitudinal section of one of the ball joints constructed according
to my invention for coupling lengths of pipe together in dredging machines.
Figure 12 is a plan, and
Figure 13-a side elevation of a rotary cutter or excavator constructed according
to my invention.
Figure 14 is a central vertical section and
Figure 15 is a transverse vertical section of a centrifugal pump for dredging
purposes constructed according to my invention.
Figures 16, 17 and 18 are respectively a side elevation, an end elevation and a
plan with the upper portion removed of a case or jacket that I sometimes provide
outside the main stuffing box or bearing of centrifugal dredger pumps in order to
keep said bearing air tight cool and free from grit.
Similar letters of reference indicate either the same or else corresponding parts
throughout the several figures of the accompanying drawings.
A, Figures 1, 2 and 3 represents the circular dredger hull which is adapted to be
secured in its working position by means of a vertical moving spud or pile B which
passes centrally therethrough. C represents the framing which is supported by
This
wheels or rollers running in the circular way c¹ on the deck of the hull A.
framing C is adapted to support the discharge tube D and it is provided with a
pinion E gearing with the circular rack e arranged upon the deck of the hull A
concentrically with the circular way c. A winch is also supported on the framing C
and may be employed to impart motion to the pinion E in order to rotate the circular
hull A bodily so as to adjust the cut of the excavator or rotary cutter F to the right or
left as desired. This winch has a winding drum 1 around which are passed the
lifting chains, g. It is driven by a pair of suitable cylinders 2 and a clutch 3
is provided upon the shaft 4 of the winding drum in order that it may be thrown
out of gear when it is desired to drive the hull adjusting pinion E which is likewise
arranged to be thrown into or out of gear with the winch when desired by means of
the lever 5. A band brake 6 is provided on one end of the winding drum 1 in order
to facilitate or regulate the working of the winch. The frame C is secured in position
by a second mooring spud or pile G as clearly shewn in Figures 1, 2, and 3 of the
drawings. Alongside each of the two spuds B and G are vertical masts 6 and g
which are firmly secured to the fixed framing C and are each provided with suitable
For this
lifting tackle whereby the spuds may readily be raised when desired.
purpose the lifting chains b', gl, are passed over pullies 62 and g² on the mast b and g
and are secured at their ends to eye-bolts 63 and passing through the upper
portions of the said mooring spuds.
The discharge tube D leads from the periphery of the centrifugal pump H up
through the deck of the dredger hull at h and thence over the framing C to any
desired spot. It will be noticed that this pipe passes through the deck as near to the
central mooring spud B as is practicable the object being to reduce the deviation and
elongation of the discharge tube D as much as possible when the dredger hull is

page_text: rotated. In order that this said tube may adjust itself to the varying positions of the
hull as compared with the platform or framing C I provide it with a telescope joint &
as well as with a ball joint as shewn.
I prefer to support his discharge tube upon the fixed frame C as illustrated in
Figures 6 and 7 that is by a step bearing carried by a pendant bracket d³ bolted
to said frame and 1 provide it with a stunng box and gland in order that it may
readily turn in any desired direction. This device for supporting the discharge tube
may also be employed with the ordinary style of dredger it being only necessary to
bolt the step bearing and the strap around the stuffing box to the side of the hull
instead of to the fixed frame as clearly illustrated in Figures 6 and 7. The suction
tube I leads from the rotary cutter or excavator F and is supported as illustrated in
Figures 4 and 5 partly by an extension i which is journalled in a bearing i¹ carried
on a framing secured to the hull of the dredger; and partly by being connected
with the other portion of said pipe by the ball joint 3. To about the centre of the
vertical portion of this suction tube I are attached chains k, k, Figure 5 passing over
winches KK and adapted either to raise or lower it or to cause it to swing up side-
ways in order to lift its end clear of the water so that in the event of it becoming
choked up with clay or the like it can be raised into such a position that the clay may
be removed by hand. In order, however, to prevent as far as possible this choking
of the suction tube I 1 provide a vacuum gauge L shewn in dotted lines in
Figures 4 and 5 whereby the consistency of the material being carried up said tube
will be indicated in order that steps may be taken to reduce such consistency if
necessary by raising the excavator into clear water.
M M Figures 8 and 9 represent the pair of ball joints that I provide in the
discharge tube between each length of pipe that is carried on the pontoons N. I
prefer to construct these joints as illustrated in Figure 11 that is with a ring m
which is adapted to fit over the male end me and to be bolted to a flange on the female
end. A packing groove being formed thereby which is adapted to receive packing ma
as clearly illustrated in said Figure whereby a simple yet efficient joint will be
provided. I couple the pontoons to each other by chains O or their equivalents
secured to pins o¹¹ in each corner of the pontoons so that by slacking out the chain
on the one side and hauling on to the chain on the other side the inclination of the
pontoons one to the other may be altered so that in a long line of them they will
describe any desired curve whereby the discharge pipe may be led to any required
spot. It will be obvious also that the said pontoons will be free to rise and fall with
the waves in perfect freedom owing to the pair of ball joints M, M', which is provided
in the length of tube between the said pontoons. The rotary cutter illustrated in
Figures 12 and 13 consists of a circular frame or wheel to whose rim pare bolted
knives or cutters P. P. having their lower ends 21 turned either outwardly as
illustrated or inwardly the purpose being to cut under the material being excavated
thus greatly facilitating its removal. It will be obvious to all persons skilled in the
art to which my invention relates that by slightly modifying the construction of
these cutters P they might be arranged either vertically or radially from the rim of
the circular frame in order to adapt them to varying descriptions of work. For
instance, when arranged vertically the excavator might be employed for cutting
material above the water line it being only necessary to keep the end of the suction
pipe below.
In order to construct a more efficient centrifugal pump for dredging purposes than
has hitherto been in use I form the side plates Q of the runner so that they curve
down from the vertical and incline towards the centre of the suction pipe I as
illustrated in Figure 15. Upon the end of the driving shaft 2 of the pump. I bolt a
dividing cone and the whole is so arranged that a clear passage, which is free from
corners or sharp curves, is provided therethrough from the suction to the delivery
pipe. The vanes of the runner I construct as illustrated in Figure 14 so that the
inner ends thereof shall incline so that if produced as indicated by the dotted lines
they would form tangents to a small circle described around the centre or axis of the
runner whilst their outer ends are approximately radial therefrom and these two ends

page_text: -
if
are connected by a forward curve as shewn which is approximately an arc of a
circle thus completing a vane having as herein before stated great holding" or
propelling powers and but little tendency to "slip."
Rrepresents the tube leading to the stuffing box of the pump driving shaft q from
a cistern r holding a supply of water at a sufficient "head" to cause a flow through
said stuffing box and into the pump thus tending to keep said stuffing box always air
tight and free from grit or other foreign material. Instead of thus conveying the
water to the bearing I sometimes enclose the whole of the stuffing box in a case
or jacket such as S Figures 16, 17 and 18 which may either be filled with water
from time to time or may, when provided with a cover be supplied with water
under pressure, through a pipe leading from a cistern of water in a similar manner
to that just described.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
1. A dredging machine having a circular hull adapted to be rotated in order to
adjust the feed of the cutter without altering the balance of said hull substantially
as and for the purpose specified and as illustrated in Figures 1, 2, and 3, of the
accompanying drawings.
2. The combination in a dredging machine of a circular hull with a fixed frame
or platform such as 'C whereby said hull may be rotated under said frame substantially
as and for the purpose described with reference to Figures 1, 2 and 3 of the
accompanying drawings.
3. The employment in a dredging machine of a suction tube supported or partially
so in a bearing such as carried on a framing bolted to and projecting from the
hull of the dredger and having a ball or other joint in order that its end may be
'swung up clear of the water substantially as and for the purpose specified.
4. The combination with the suction pipe of a dredging machine of a vacuum
gauge whereby the consistency of the material being conveyed therein will be
indicated in order that steps may be taken to regulate it substantially as described
with reference to Figures 4 and 5 of the accompanying drawings.
5. Discharge tubes for dredging machines supported on pontoons and having
two ball joints between each pair of said pontoons substantially as and for the
purpose specified and as illustrated in Figures 8 and 9 of the accompanying
drawings.
6. The combination with a series of pontoons of the special arrangement of chains
or their equivalents arranged one on each side and two diagonally substantially as
and for the purpose specified and as illustrated in Figure 8 of the accompanying
drawings.
7. In a dredging machine the employment for coupling lengths of discharge or
suction tubes fogether of a ball joint "constructed substantially as. illustrated in
Figure 11 and consisting in the combination of a ring such as madapted to be
bolted to a flange or its equivalent on the female end of one of the lengths of tube to
be joined substantially as described with reference to said Figure.
8. In a dredging machine the employment of a rotary cutter or excavator having
knives adapted to cut under the material in order to facilitate its removal and when
slightly modified adapted to be used for cutting above the water line substantially as
specified and as illustrated in Figures 12 and 13.
9. In a dredging machine the employment of a centrifugal pump having its vanes
constructed and arranged substantially as herein described so that their outer ends
shall be approximately radial from the centre or axis of the runner whilst their inner
ends shall be tangential to a small circle described from said centre or axis, as
illustrated in Figure 14 of the accompanying drawings.
10. In a dredging machine the combination with the main stuffing box or bearing
of the centrifugal pump of a tank or cistern of water having a pipe leading to said
stuffing box or else the combination therewith of a jacket or casing such as S

page_text: Figures 16, 17, and 18 arranged around said stuffing box and either itself filled from
time to time with water or else having communication with a cistern or its equivalent
whereby it can be supplied with water under pressure substantially as and for the
purpose specified and as illustrated in Figures 14 to 18 of the accompanying
drawings.
11. The combination of parts constituting my improved dredging machine all
constructed, arranged and operating substantially as and for the purposes herein
described reference being had to the accompanying drawings.
Dated this Twentieth day of November, 1889.
CRUIKSHANK & FAIRWEATHER,
62, Saint Vincent Street, Glasgow, Agents.