Improvements in Apparatus for Use in Operating or Working Under Water.
Year: 1898

page_text: Date of Application, 19th Oct., 1898
Complete Specification Left, 15th July, 1899-Accepted, 19th Oct., 1899
Improvements in Apparatus for Use in Operating or Working
Under Water.
I, AUGUST VON HOFFMANN, of 63/1 Königinstrasse, Munich, in the Empire of
Germany, Army Major, do hereby declare the nature of this invention to be as
follows:-
The present method of conducting diving operations is very incomplete and
expensive as depths over 50 metres are at present impracticable, and any checking
or controlling of the divers by experts or the like is excluded, and machine
power can only be used in very rare cases.
This invention has for its object an apparatus which renders it possible to
execute submarine mining or to work with machinery or mechanical power from
a sunk chamber capable of being steered, whereby such work can be carried out
as could not hitherto be effected by a professional diver on account of the require-
ments being beyond human power or on account of the depths being too great.
A rectangular box or case is constructed at the front end of a working chamber
closed on all sides and of suitable form, in this case for instance having the form
of a submarine boat, said box communicating with the water by means of 'two
doors lying opposite to one another. A cock or the like valve is arranged to allow
of the pressure in the box being equalized with that of the outside water if
desired.
A pipe with a shut off tap connects the interior of the box with a small water
reservoir, arranged beneath the same. On the inner door two ball and socket
joints carry the work bars. The balls are centrally perforated in order to give
passage to an exactly calibrated and tight washered tube or hollow rod which
carries the removable tool and according to requirements may be extended and
moved forward and backward. A guide sleeve screwed firmly to the ball carries
in a casing cast thereon a device for pushing forward the hollow rod, which device
consists of friction rollers. The friction rollers which are actuated by cogwheels,
and are pressed on the rod by means of springs, move the rod forwards or
backwards according to the direction of movement imparted to a handwheel
suitably connected therewith.
A support which is also operated by means of a handwheel is also provided on
the pushing forward device and if desired the guide sleeve may be fixed to said
support.
The dimensions and distances are so calculated that a man of average size
looking through the window placed above and at the side of the box in the
front wall of the apparatus can operate with one hand the driving wheels of the
bar and the support and with the other can hold the handle fast. He thus stands
leaning against the side wall of the apparatus. The tools are screwed on the
specially shaped member of the bar and maintained in position by cotters, whilst
stuffing boxes are employed for forming tight joints for this and the other parts
of the bar or frame
.

page_text: The tubes or hollow rods are cylindrically bored and carry (as integral con-
stituents) cylindrical bars of suitable length according to the requirements of the
tools whereby the tubes may be suitably extended or lengthened.
The tools employed are:
1. A screw wrench having a variable width of jaw and different widths of
grip and different directions of engagement.
2. A borer; mills or rimers; circular saws; earth borers and mud or clay
spiral cutters.
3. Hooks, scoops, shovels, counterholders, simple spikes or points and the
like.
4. A hammer with a driving device.
The jaw carriers are screwed on the tubular bar and the tightening screws
on the inner rod. The tool may be connected with the inner rod and set in rotation
from the engine by means of a flexible shaft connected with the last named member
or by means of a belt gearing. The outer rod thus serves only as a guide. In
a third case the tool may be mounted on the tubular rod and the inner rod not
work. In a fourth case the driving device of the hammer may be connected with
the flexible shaft.
A two armed key capable of being fixed may be used for turning the inner
rod for instance, when using the screw key.
The hammer moves in a cylindrical tube washered against outer pressure. A
large spiral spring arranged in said tube presses the hammer forwards and the
hammer is mounted on an inner rod capable of being released by being rotated.
The rod leads to a cross head, which moving in a tube several times slotted is
drawn backwards by means of a threaded bar and pressed by means of a lever
on the gear of the rotating belt of flexible shaft.
A lever is arranged when pressed downwards to release the connection of the
hammer with the inner bar and the latter is again connected with the hammer
by means of a spiral spring in a suitable position of the lever. The hammer
strikes with its entire weight plus the speed imparted by the spring. It either
works freely or under the guidance of two bars which hold bolts or pins or the
like.
The assistant ship is a small steam boat or barge of 20-200 tons with powerful
machinery, carrying on board a dynamo machine, steam winches, extra long
anchor chains, buoys, smiths' portable forge, smiths' tools and the like.
object is to convey the apparatus to the place of destination and there to assist
it at work.
Its
In order to attach the tools or work pieces to the rod and tube, the water
filling the closed box is let off into the reservoir. A rapid and excessive inflow
of water indicates that the outer door is not tight and this drawback is removed
by tightening the screw. The inner door is screwed off and swung back. The
outer ends of the bars then lie free, the tools are screwed on, the inner door
closed, the water filling the box is pumped out of the reservoir and the connecting
valve opened. Any penetration of water into the working chamber shows that
the inner door is not tight. The frame of the outer door is then released by
revolving the screw and the outer door is let down by means of a
cog gearing. It is self evident of course that before this the apparatus must have
been brought into the indicated position suitable for work and have been anchored.
The borer or rimer heads are attached to the object and pressed down by the
driving mechanism.
worm
or
The operation in the case of saws is similar. Wire ropes up to 15 centimetres
in thickness may be gripped by a fork intended therefor and for the purpose of
being cut are raised against the saws by hook shaped loops on the two bars.
Fixed objects are freely sawn through, but in the case of a long bar, great vibra-
tions or strong current, both rods are coupled by an adjustable device and the
second bar is armed or shod if required (for instance with a simple pricking
point or with keys) and employed as a holder or support.

page_text: Metal is treated in a similar manner by means of rimers or borers. Bore holes
are made in iron for blasting. The screw keys or wrenches serve more particularly
for placing lifting devices and blasting charges and only the smaller objects are
directly operated on from the inside. Larger loads are fixed on catching devices,
boxes, or the like conveyed by assistant ships or barges.
Blasting charges are connected, either separately or several together, with an
igniting cable and inserted either in the previously bored shot holes or attached
by means of tamping plugs, wire loops or sheet metal spring clamps. Series of
charges are carried in a basket which are well packed and pushed forward by the
second or inner rod.
The igniting cable itself is wound on a reel which is operated on the inner
left hand side of the box by means of a crank which passes through the wall of
the box and is tight washered. The cable follows the movement of the bar
carrying the charge, and the reel axle is perforated and conductingly connected
with the motor. After the shot has been fired the remainder is wound up in order
not to render the outer door untight.
Sinkers with a separate head and earth borers, suitably protected, serve for
drawing lines through and under the object. Scrapers, picks, crowbars, shovels,
baskets, scoops are employed for removing small quantities of mud and sand.
Assistant baskets supplied from the tender may in this case be employed.
The best method of connecting the tender or the like with the object is by
means of guide ropes hanging to buoys and anchors. This must especially be
the case when bad weather, great depths or currents deleteriously affect the quiet
floating of the tender over the place.
In order, in case of need, to be able to firmly support the apparatus on the bed
of the sea and protect it against oscillation, struts provided with teeth are attached
in front and behind to the side and may be worked on the ground from the
working chamber by turning crank handles or the like.
The following is a device for cutting through strong constructions, such for
instance as the sides of ships. It consists of a circular saw which is mounted
on the head of the shaft or inner rod and is operated by a worm gear arranged
thereon. The attack of the saw is regulated by the adjustment of the shaft.
The tubular rod is also provided with a head which carries on a screw bolt a
cogwheel and a clamp jaw. A second clamp jaw is attached to the last mentioned
head and a subsidiary shaft is also carried thereon, the cogwheel of said shaft
engaging in a lateral toothing or face toothing of a wheel, a second cogwheel,
being carried on the inner end of the shaft which cogwheel is set in rotation from
a cogwheel of the main or tubular rod and may be thrown out of gear by adjust-
ment or displacement when the subsidiary shaft is not in use. If a ship's side
is to be cut through with this apparatus, two bore holes are formed in the ship's
side in the direction of the cut which is to be made and in these bore holes two
hooked bolts are inserted carrying a plate, said plate being pressed against the
ship's side by screwing up pressure screws. The tightening of the screws and
also the nuts on the hooked bolts takes place by means of a key having a bayonet
joint mounted on a loop piece of the tubular rod, which key is pushed over the
screw heads provided with lateral projections. A bar is revolubly mounted on
the plate and the saws are mounted on this bar by means of two clamp jaws,
the one jaw with its strip being pressed into the guide groove of the other jaw.
This pressing in takes place by tightening a screw by means of a lug mounted
on the rod of the second bar, this latter being successively placed on the arm of
the screw and drawn tight. Two screw bolts are mounted on the plate and also
on the bar, by means of which screw-bolts the bar can at any time be adjusted
in the direction of the inner rod and be fixed. It is also operated by means of
said lug. The bar has teeth on its upper edge in which a toothed wheel engages.
When the saw has been installed on the side of the ship and set in operation by
means of the inner rod or shaft, it is moved forward to a suitable extent to corre-
spond with the action of the saw by the action of the shaft on the bar. The bar

page_text: thus works to a certain extent as a rule which determines the direction and
angle at which the cut shall take place.
Screw pincers are also provided which also may be screwed on the free end of
the rod or bar. Two arms are pivotally mounted on the head serving for this
purpose, and screw nippers are pivotally mounted on the lateral pins of these two
arms. The shaft has here at its screwed end a cross head which presses with its
band against the inner side of the arms on the screw being rotated backward, and
forces said arms and with them the two jaws apart. The cross head is on the
other hand carried or guided with its widened end in grooves of an arm in such
a way that a rotation of the screw in the said direction automatically causes a
drawing together of the arms and therewith of the jaws or screw nippers. The
subsidiary shaft is also connected by means of two levers with the jaws so that
by turning the subsidiary shaft which is provided with a thread an adjustment of
the lever and by means of the latter an adjustment of the jaws on their point of
rotation takes place.
In the construction of the working chamber, the box may in case of need be
arranged on the bottom of the same with slight modifications so that the working
may be carried on with the bars in a vertical direction.
The several tools and appliances used with the apparatus may be of any known
suitable construction, and those which have been hereinbefore mentioned have
been merely described as examples of the manner of using the apparatus.
D
.
1000
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.
Improvements in Apparatus for Use in Operating or Working
Under Water.
I, AUGUST VON HOFFMANN, of 63/1 Königinstrasse, Munich, in the Empire of
Germany, Army Major, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:--
The present method of conducting diving operations is very incomplete and
expensive as depths over 50 metres are at present impracticable, and any checking
or controlling of the divers by experts or the like is excluded, and machine
power can only be used in very rare cases.
This invention has for its object an apparatus which renders it possible to
execute submarine mining or to work with machinery or mechanical power from
a sunk chamber capable of being steered, whereby such work can be carried out
as could not hitherto be effected by a professional diver on account of the require-
ments being beyond human power or on account of the depths being too great.
In the drawings accompanying this specification,
Figures 1-6 are only intended to demonstrate the method of arranging the
working apparatus in a floating body capable of being sunk, such for instance
as a caisson or the like (in the case shown in the drawings a submarine boat).
They form no part of the patented process and no claim is made for the tools,
Figures 15-28, which are only those usually employed and which are only
inserted to allow of the invention being better understood.
A rectangular box or case g is constructed at the front end of a working cham-
ber a closed on all sides and of suitable form, in this case for instance having

page_text: the form of a submarine boat, said box communicating with the water by means
of two doors h and i lying opposite to one another. A cock or the like valve 2,
(Figures 2 and 13) is arranged to allow of the pressure in the box being equalized
with that of the outside water if desired.
A pipe with a shut off tap connects the interior of the box g with a small
water reservoir k, Figures 1 and 12, arranged beneath the same. On the inner
door two ball and socket joints carry the work bars, Figures 1, 9 and 12. The
balls are centrally perforated in order to give passage to an exactly calibrated
and tight washered tube or hollow rod n, Figures 29 and 31, which carries the
removable tool and according to requirements may be extended and moved
forward and backward. A guide sleeve m screwed firmly to the ball carries in a
casing cast thereon a device for pushing forward the hollow rod n, Figures 9,
29 and 30, which device consists of friction rollers o. The friction rollers which
are actuated by cog-wheels, and are pressed on the rod by means of springs, move
the rod forwards or backwards according to the direction of movement imparted to
a handwheel H suitably connected therewith.
A support P, Figures 9 and 10, which is also operated by means of a hand-
wheel G is also provided on the pushing forward device and if desired the guide
sleeve m may be fixed to said support.
The dimensions and distances are so calculated that a man of average size
looking through the window c placed above and at the side of the box in the
front wall of the apparatus can operate with one hand the driving wheels of the
bar and the support and with the other can hold the handle fast. He thus stands
leaning against the side wall of the apparatus. The tools are screwed on the
specially shaped member of the bar and maintained in position by cotters, whilst
stuffing boxes are employed for forming tight joints for this and the other parts
of the bar or frame.
The tubes or hollow rods are cylindrically bored and carry (as integral con-
stituents) cylindrical bars r of suitable length according to the requirements of
the tools whereby the tubes may be suitably extended or lengthened.
Figures 31 and 32 show two extensions or elongating pieces of the combined
rod nr. Figure 33 shows in detail the method of connecting the same.
The tools employed are:
1. A screw wrench, Figure 15, having a variable width of jaw and different
widths of grip and different directions of engagement, Figures 18 and 19.
2. A borer, Figure 17; mills or rimers, Figure 16; circular saws, Figures 22
and 23; earth borers and mud or clay spiral cutters, Figure 25.
3. Hooks, scoops, shovels, counterholders, simple spikes or points and the
like.
4. A hammer with a driving device, Figures 26, 27 and 28.
In the first of the above cases the jaw carriers are screwed on the tubular bar m
and the tightening screws on the inner rod r. In the second case the tool may be
connected with the inner rod r and set in rotation from the engine by means of a
flexible shafts, Figure 20, connected with the last named member or by means
of a belt gearing. The outer rod thus serves only as a guide. In the third case the
tool may be mounted on the tubular rod n and the inner rod not work. In the
fourth case the driving device of the hammer, Figure 27, may be connected with
the flexible shaft s.
n
In Figure 21, 3 indicates a two armed key capable of being fixed for turning
the inner rod for instance when using the screw key.
The sectional Figure 26 shows a hammer which is moved forward and backward
in the axial direction of the rod r. t is here the hammer head, the hammer
weight. Both are inserted in a cylinder z screwed on the tube n, and secured
against rotation by two studs T, engaging in longitudinal grooves on the weight
(see cross section II of Figure 26). The forward and backward movement of
the hammer takes place by means of the rod r which is attached to the hammer
weight t¹ by means of a bayonet joint in such a way that the connection between

page_text: the rod and the weight may be released by turning the rod r by means of a
lever (Figures 7 and 28,) whilst the connection may be again made by turning
it back again, as will be hereinafter explained. The reciprocation of the rod r,
and therewith of the hammer takes place by means of the mechanism shown
in Figure 27, in side elevation partly in section and in the cross section on
line II II of Figure 27 and in Figure 28 in plan view. In these figures w° is a
sleeve screwed on the tube n in the working chamber. a is the lever for turning
the rod for the purpose of coupling the same with the hammer weight t¹. A
spring presses the rod r constantly against the weight t so that when the
lever is placed in a suitable position, the lug of the bayonet joint automatically
enters the groove in the weight t', and in order to effect the coupling it is only
necessary to turn the rod r. The drawing back of the hammer t takes place by
a rod which is located in the sleeve w° and adapted to be rotated by the flexible
shafts, which rod is provided with a screw thread v₁ guided in a half cylinder w²
which is connected with the rod r. The thread engages in an internal thread
formed in a bar v capable of being turned back on a hinge 3, whereby the bar v
may be disengaged from the screw . The forward springing of the hammer
head t takes place each time by means of a spring of suitable strength located
in the cylinder z Figure 26.
The hammering takes place in the following way:
The bar is held down on the screw by means of a lever w by hand, and
the said screw is operated by the shaft s whereby the hammer t is drawn back,
and the spring u thereby compressed. The bar is then thrown up by hand
to disengage it from the screw so that the spring u can push the hammer
forward.
The assistant ship is a small steam boat or barge of 20-200 tons with powerful
machinery, carrying on board a dynamo machine, steam winches, extra long
anchor chains, buoys, smiths' portable forge, smiths' tools and the like. Its
object is to convey the apparatus to the place of destination and there to assist
it at work.
In order to attach the tools or work pieces to the rod and tube nr the water
filling the closed box g is let off into the reservoir k. A rapid and excessive
inflow of water indicates that the outer door is not tight and this drawback is
removed by tightening the screw 1. The inner door h is unscrewed and swung
back The outer ends of the bars then lie free, the tools are screwed on, the inner
door closed, the box refilled with water pumped out of the reservoir k and the
connecting valve Figure 13 opened. Any penetration of water into the working
chamber a shows that the inner door is not tight. The frame of the outer
door is then released by revolving the screw 1, and the outer door i is let down
by means of a worm and cog gearing, Figures 8, 12 and 14. It is self evident of
course that before this the apparatus must have been brought into the indicated
position suitable for work and have been anchored. The borer or rimer heads
(Figs. 16 & 17) after attachment to the rod nr are placed against the object to be
operated on and moved forward during the boring by the mechanism o (Figs. 29,
30, and 34).
The operation in the case of saws is similar. Wire ropes up to 15 centimetres
in thickness may be gripped by a fork intended therefor and for the purpose of
being cut are raised against the saws by hook shaped loops on the two bars.
Fixed objects are freely sawn through, but in the case of a long bar, great vibra-
tions or strong current, both rods are coupled by an adjustable device, Figure 24,
and the second bar is armed or shod if required (for instance with a simple
pricking point or with keys) and employed as a holder or support.
Metal is treated in a similar manner by means of rimers or borers. Bore holes
are made in iron for blasting. The screw keys or wrenches serve more particularly
for placing lifting devices and blasting charges and only the smaller objects are
directly operated on from the inside. Larger loads are fixed on catching devices,
boxes or the like conveyed by assistant ships or barges.

page_text: Blasting charges are connected, either separately or several together, with an
igniting cable and inserted either in the previously bored shot holes or attached
by means of tamping plugs, wire loops or sheet metal spring clamps. Series of
charges are carried in a basket which are well packed and pushed forward by the
second or inner rod.
The electric igniting cable itself is wound on a reel, Figure 11, which is located
inside of the box g and is operated by means of a crank which passes through the
wall of the box and is tight washered. The cable is carried to the current supply
within the working chamber through the reel axle which is perforated for the
purpose. After the blasting charge on the other end of the cable has been placed
in position a suitable amount of cable is wound off the reel to prevent the cable
tearing away from the charge when the boat moves out of reach of the explosion
before the charge is ignited. After the shot has been fired the remainder of the
cable is wound up on the reel in order not to get caught in the bearings of the
outer door which would prevent the latter being closed watertight.
Sinkers or earth borers such as shown in Figure 25, attached to the rods n r are
used for drawing lines under the object to be operated on, the lines being tied
firmly but releasably to the borers, and the latter then driven under the object.
The line is then released by means of a side rod, and taken up on the other side
of the object by the same or a second driving apparatus. Scrapers, picks, crow-
bars, shovels, baskets, scoops are employed for removing small quantities of mud
and sand. Assistant baskets supplied from the tender may in this case be
employed.
The best method of connecting the tender or the like with the object is by
means of guide ropes hanging to buoys and anchors. This must especially be
the case when bad weather, great depths or currents deleteriously affect the quiet
floating of the tender over the place.
In order, in case of need, to be able to firmly support the apparatus in any
desired position by shoring on the bed of the sea and protect it against oscillation,
struts 4, Figures 2 and 6, provided with toothed gearing (Figures 38 and 39) are
attached in front and behind to the side and may be worked on the ground from
the working chamber by turning crank handles or the like.
Figure 44 shows diagrammatically a device for cutting through strong construc-
tions, such for instance as the sides of ships. This device is shown in Figures 41
and 42 and in detail in Figure 43. It consists of a circular saw 7 which is mounted
on the head of the shaft or inner rod and is operated by a worm gear 8 arranged
thereon, Figure 43. The attack of the saw is regulated by the longitudinal adjust-
ment of the shaft r. The tubular rod is also provided with a head which
carries on a screw bolt 19 a cogwheel 9 and clamp jaws 10 and 11. On the last
mentioned head a subsidiary shaft r' is also carried having a bevel wheel engaging
in a lateral bevel toothing on the wheel 9, a second cogwheel 12, Figure 40 being
carried on the inner end of the shaft r, which cogwheel is set in rotation from
a cogwheel 13 of the main or tubular rod n and may be thrown out of gear by
adjustment or displacement when the subsidiary shaft is not in use. If a ship's
side is to be cut through with this apparatus, two bore holes are formed in the
ship's side 14, Figure 42, in the direction of the cut which is to be made and in
these bore holes two hooked bolts 15 are inserted carrying a plate 16, Figures 41,
42, and 43, said plate being pressed against the ship's side 14, by screwing up
pressure screws 24, Figure 42.
The tightening of the screws 24 and also the nuts on the hooked bolts 15
takes place by means of a key 17, having a bayonet joint mounted on a loop
piece of the tubular rod n which key is pushed over the screw heads provided
with lateral projections (Figure 42). A bar 18 having its edge toothed (Figures 43
and 44) is hinged on the plate 16 and the circular saw is mounted on this bar
by means of the two clamp jaws 10, 11 (Figure 41) in the following manner:―
The two clamp jaws 10 and 11 are pushed over the bar 18 by means of the rod n
until a projection R on the jaw 10 engages in a groove in the bar 18 and the

page_text: toothed wheel 9 engages the teeth of the bar 18. Both jaws 10 and 11 are then
tightened up by screwing up the nut 28 on the screw 19 but not so as to be
rigidly fixed to the bar 18. This tightening up takes place by means of a
socket on the end of subsidiary rod which is engaged successively on the
three arms 29 of the nut 28 and drawn back, thus causing a rotation of the nut.
The bar, 18 must of course always stand in a plane parallel to the axis of the
rod r, and for this purpose in order to allow of the bar being rapidly and exactly
adjusted. by being turned on its hinge, two set screws 20 are employed which
are mounted by one end in the bar 18 and by the other end in the plate 16,
Figures 42 and 44. The forward or backward movement of these screws and the
corresponding adjustment of the bar 18 takes place by turning nuts 30 mounted
on the free ends of these screws. This turning takes place in a similar manner
to the one previously described for the nut 28 by means of the socket 7° of the sub-
sidiary rod r.
The bar 18 has teeth on its upper edge in which the toothed wheel 9 engages.
When the saw has been installed on the side of the ship, as shown in Figure 41,
and set in operation by means of the inner rod or shaft r it is moved forward to a
suitable extent to correspond with the action of the saw by the action of the
shaft on the bar 18. The bar thus works to a certain extent as a rule which
determines the direction and angle at which the cut shall take place:
" :
Figures 45, 46 and 47 show in two elevations and a cross section respectively
screw pincers which also may be screwed on the free end of the rod or bar n.
Two arms 21 are pivotally mounted on the head serving for this purpose, and
screw nippers 22 are pivotally mounted on the lateral pins of these two arms.
The shaft has here at its screwed end a cross head 25 which presses with its
rounded head against the inner side of the arms 21, on the screw being rotated
backward, and forces said arms and with them the two jaws apart. The cross
head is on the other hand carried or guided with its head, Figure 47 in grooves
in the arms 21 in such a way that a rotation of the screw in the said direction
automatically causes a drawing together of the arms 21 and therewith of the
jaws or screw nippers 22. The subsidiary shaft r is also connected by means of
two levers 23 with the jaws 22, so that by turning the subsidiary shaft which
is, provided with a thread an adjustment of the lever 23 and by means of the latter
an adjustment of the jaws 22 takes place on their point of rotation.
'
Figures 34, 35, and 37 show the mounting of the subsidiary shaft in the
ball joint and also the device for pushing the bar forward.
Figure 36 shows the connection of the extension pieces of the subsidiary
shaft and Figure 40 the rear coupling of the subsidiary shaft with the main
bar n and the flexible shaft s.
In the construction of the working chamber a the box g may in case of need be
arranged on the bottom of the same with slight modifications, Figures 6 and 7;
so that the working may be carried on with the bars nr in a vertical direction.
The several tools and appliances used with the apparatus may be of any known
suitable construction, and those which have been herein before mentioned have
been merely described as examples of the manner of using the apparatus.
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:
1. A tool or implement operating apparatus for diving boats or the like for
carrying out operations or work at great depths under water, consisting of a
box or case (g) arranged inwards in the side or bottom wall of the boat or the
like, which box by means of an outer closing adjustable door (i) and an inner
trap door (h) renders possible the interchange and use under water of implements
or tools which are attached to the latter by means of extensible rods movable in
ball joints, substantially as herein before described.
2. In a diving boat or the like such as described, the arrangement on the side

page_text: walls of the same of supports or struts (4) in such manner as to enable said diving
boat to be firmly fixed in any desired position relative to the object to be operated
on by shoring, said struts having toothed mechanism, which can be operated
from within the boat by means of suitable mechanism substantially as described.
Dated this 14th day of July 1899.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.