US849378A - Floating dry-dock. - Google Patents

Description

No. 849,378. PATENTED APR. 9, 1907. W. T. DONNELLY.

FLOATING DRY DOCK.

APPLICATION FILED SEPT. 24,1906.

7 SHEETS-SHEET 1.

PATENTED APR. 9, 1907.

. T. DONNELLY.

FLOATING DRY DOCK.

APPLICATION FILED SEPT. 24,1906.

7 SHEETS-SHEET 2.

No. 849,378. PATENTED APR. 9, 1907. W. T. DONNELLY.

FLOATING DRY DOCK.

APPLIOATION FILED SBP'1.24,1906.

7 SHEETS-SHEET 3.

QXlLY-mc ow Snow W06, Wf W: 7782M 7720mm Donnell flap/254w; 95 fitter/M1 4 PATENTED APR. 9, 1907.

W. T. DONNELLY.

FLOATING 'DRY DOCK.

APPLICATION FILED SEPT. 24,1906.

7 SHBBTSSHBET 4.

No 849,878. PATEN'IED APR. 9, 1907. w. T. DONNELLY. FLOATING DRY DOCK.

APPLICATION FILED SEPT. 24,1906.

7 SHEETS-SHEET 5.

PATENTED APR. 9, 1907.

W. T. DONNELLY. FLOATING DRY DOCK. APPLICATION IIILED SEPT. 24,1906.

7 SHBETSSHEBT 6,

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PATENTED APR. 9, 1907.

W. T. DONNELLY. FLOATING DRY DOCK. APPLICATION FILED SEPT. 24, 1906.

7 SHEETS-SHEET 7.

ammo whom 750m fl nnel lj $2M. at 121g UNITED srn'rns PATENT GFFIOE.

WILLIAM THOMAS DONNELLY, OF BROOKLYN, NEW YORK.

FLOATING DRY-DOCK.

Specification of Letters Patent.

Patented April 9, 1907;

Application filed September 24, 1906. Serial No. 335,388.

-T-1tll whom it may concern.-

Be it known that 1, WILLIAM TnoirAs DONNELLY, a citizen of the United States, re-

' siding at Brooklyn, in the county of Kings and State of New York, have invented certam new and useful Improvements in Floating Dry-Docks, of which the following is a specification.

My invention relates to improvementsin floatin dry-docks.

v In a l floating dry-docks the safety of the dock and vessel depends upon the proper distribution and control of the pumping-power,

and as the floating dry-docks in use at present require so much machlnery, valves, and

other parts for their operation and control it is consequently necessary to employ a number of men under the direction of a dockmaster, who, while responsible, has to depend to a great extent upon those under him for the control of the dock and vessel. It has also been the practice to provide floating drydocks with pumping machinery located upon the dock itself, this machinery being in the nature of a plurality of separate pumps, one

or more being located in each separate pontoon or water-tight compartment of the dock and alldriven from the same source of power, and in some cases one or more large pumping plants have been employed to which water was conducted under the control of valves from the various pontoons of the dock. The first method above referred to required a great multi lication of mechanicalparts, and

consequent was complicated and dii'licult of control, an the second method was hardly more desirable with its complication of valves and pipes, and both of these methods of pumping had the'further disadvantage that the pumps and power plant were available for. .useonly upon the particular dock for which they had been designed.

' My invention therefore has asits object ,to

accurately control a dock while being raised" or lowered, no matter what the position or the size of'the vessel may be which it is employed to dock, by providing simple and efli cient means for producing air and supplying it under pressure to the compartments thereof,

for controlling the delivery of air to and ex haust of air from said compartments, and for [controlling the delivery of water to and ex-' 'haust of water from said compartments,

whereby an or water may be delivered to or I exhausted from any desired combination of compartments or the dock as a whole, as may be required.

An important part of my invention is the control of the discharge of water from the various compartments. I speak of the discharge of the water in contradistinction to the control of the delivery of the air into the difierent compartments-for the following reasons: When air is to be delivered into a submergedcompartment or pontoon at a distance below the surface of the water it is necessary to deliver the air at a pressure equal to the hydraulic head at which the pontoon is submerged. If the delivery of the air to the pontoon is controlled and the delivery of the water uncontrolled, alifting effect will be produced; but it will not be under control, for as soon as the pontoon commences to rise the hydraulic head is decreased, and

even if the supply of air is immediately cut off the air that is within the pontoon (which in the case of a floating dock maybe of large toons individually and collectively I en-' tirely overcome this difficulty and all objection to the use ofair.

Another feature of my invention is to make of the wings closed com artnients, without inlet or outlet valves, an the dimensions of the wings such that when all the pontoons of the dock are completely flooded the dcscent of the dock will be automatically arrested at the maximum depth for which it is designed. a

It has for afurther 0b ect to provide means whereby when two or more docks are other all can be pumped by the same airproducing means that would ordinarily be re uired for one, this being of particular ya no in connection with. floating dry-do(ks, as the Work they have H2 perform is of such nature that they re-run .a. very large mount located in the immediate vicinity of one anof power for a very short time-say, from one to two hours a day, or even for not more than two or three hours a week.

Referring to the drawings, Figure 1 is a side elevation of a floating dry-dock embodying my invention; Fig. 2, a top plan view; Fig. 3, an end elevation. Fig. 4 is a side elevation of one side of the dock, showing the PQSition the dock assumes when elevated; Fig. 5, a side elevation of one side of the dock, showing the position the dock assumes when lowered and submerged. Fig. 6 is a to'pf'plan view of a number of dry-docks pumped from a common source of power. F ig: 7 is an end view of one of the pontoons, partly in section. Fig. 8 is a side view of one of the pontoons, partly in section. Fig. 9 is an end elevation of the dock, showing the position of the several parts when the dock is listed sidewise. Fig. 10 is a side elevation of the dock,showing the positions ofthe several parts when the dock is inclined longitudinally. Fig. 11 is a side elevation, partly in section, on an enlarged scale, of the mechanism for effecting a change in level of thedischarge-outlets. I Fig. 12 is an end View of the mechanism shown in Fig. 1 1.

Referring to the drawings, in which like reference characters denote like parts throughout the several views, 1 represents the floating dry-dock, which as shown is composed of a series of five pontoons 2 but which may comprise a greater or less number, as may ,quirements.

I Side walls or wings 3, which are hollow and be found necessary to meet the different remade air and water tight, are mounted on the pontoons in the usual manner and secured by suitable bolts 4. The pontoons are also provided with'theusual keel-blocks 5 and bilge-blocks 6.

The pontoons are each providedwith a Ion- V gitudinal' central bulkhead 7 and with a floodgate 8, said flood-gate being opened and closed by means of a rod 9, which is mounted in a bracket 10, projecting laterally from the top of the side wall or wing 3, and said rod being screw-threaded at its'upper end and provided with a hand-wheel 11, by which it is operated. A short section of pipeS extends inwardly from each of the flood-gates of the pontoons and is provided with a checkvalve 8* at its inner end to prevent the egress of water by way of the flood-gates. (See Fig. 8.) Each pontoon is also provided with a water-outlet 12, which comprises a number of extensible and retractible telescopic tubesections 13j '1-4, and 1.5, the section 13 being mounted in the pontoon and its lower end terminating near the bottom thereof and the section 15 being provided with a laterallyex-tending nozzle or mouth 16, which is designed to always be above the surface of the water floating the dock. I f

The means for raising. andlowering the saasv's;

outlets 12'simultaneously comprises shafts 17, extending longitudinally on each side of the dock and mounted in hangers 18, se

cured to lateral projections on the tops of the win sand provided with drums 19, which are oose on the shaft, and on each of which is wound one end of a rope or chain 20, while the other end of said rope or chainis attached to the section 15 of the telescopicoutlet 12, and for turning the shaft 17 a motor 21 is employed, which maybe operated by electricity, compressed air, or any other power, and which is operatively connected to a sprocket-wheel on the shaft 17 by means ofa sprocket-chain 21. To keep the drums from moving laterally, sleeves 22 are provided, which are clamped to'the shaft 17 on opposite sides of the drums.

To provide means to raise and lower the outlets independently of each other, each drum 19 is provided with a worm-gear 23 and a vertical shaft 24, provided with a worm 25, designed to engage said worm-gear, said shaft being pivoted to a bracket 26, extend- I and provided with a hand-wheel 27 at its up- 1 per end, by which it is operated. The shaft 24 passes through an elongated slot 28 in thebracket 10 and a slidable latch 29 is provided, which normally holds the shaft 24 and worm out of engagement with the worm-gear of the drum.

For throwing each of the-drums 19 into 9 eration-that is, so that it will move with t e shaft 17a two-part clutch 30 is 'provided, one part 31 of which is formed on the side of the drum l9'and the other part or jaw 32 slidably. mounted on the shaft 17,

and a forked lever 33 is operatively connected to said jaw for causing the two parts of the clutch to engage and disenga e.

To raise or lower one of the outlets independently of the-others, the latch 29 is withdrawn and the inclination of the shaft 17 is changed so as to. bring the worm 25 into engagement 'with the worm-gear 23. The forked lever 33 is then moved into position shown by the dotted lines, (see Fig. 11,) carrying the jaw 32 with it, and thus releasin 17. Then by turning the hand-wheel in either direction the outlet will be raised or lowered as to any desired elevation.

34 is a pipe which is connected with any suitable air-su ly under pressure situated on the pier, said pipe being provided with a main valve 35 for controlling the air-supply and a valve 35 having a discharge 36 to the atmosphere, and 37 are branch pipes having valves 37 and extending laterally from the pipe 34 along eachside of the dock to towers T39, and at said towers are connected with horizontal pipes 49' on the dock by flexible means, such as flexible pipes 41, for the purg I S the drum 19' from engagement with the shaft.

- Having described my invention, the operation of the dock in handling a vessel of'the full size of the dock is as follows: The dock' will be considered as raised and ready for sinking, with keel and bilge'blocks prepared for a vessel. Under these conditions the main valve 35 in the air-supply pipe is closed and, the relief-valve 35* to the atmosphere and" the valves 37 are open. All the flood- I 5 .gates 8 to the various compartments of the pontoons are closed. The deck of the dock (the part upon which the keel and bilge blocks rest) is presumed to be from one to two feet above the surface of the water and the water within the pontoons. about four feet below that on the outside, (an amount sutlieient to represent the structural weight of the deck.) The first oration will be to partially open all the floo -gatcs S and allow the water to flow into the interior of the various com partments', when the dock will at onee commence to sink, and as it does so one side which may have had its valves opened wider or sooner than the other may settle faster. instead of ordering the valves'partly closed on that side will close or partly close the valve 37 on the side of the dock which is fillin'g too quickly. This will have the effect of holding in the air on that sideof the dock and retarding the inrush of water and bring the dock to an even keel. As the deck of the (lock comes near the surface of the water the flood-gates will be nearly closed and the dock will be carefully leveled by controlling the water-inlets and the air-outlets from each side. The dock will then be allowed to settle until the water floods the deck, and will then be found to settle much faster with the same opening of gates. The dock will continue to descend as long as water is allowed to enter the pontoons or until they are full. In this case the side walls will su ort the entire structural weight of the doc k. It is not the intention to allow water to enter the side walls at anytime, and their size is such that thev'will limit the sinking of the dock to the maximum depth for which it is designed, '1 hi s furnishing a safeguard against the sinkw ing of the dock by accident. During the sinking the dock has been controlled laterally by controlling the escape of the air, and its descent can finally be entirely -arrested by entirely preventing the escape of the air by closing the relief-valve 35. When the deck of the dock is submerged, the motors :31 on each wing of the dock are started up and the outlets 12 are raised as fast as the dock is lowered, thus kee' ing them in about the same relation to t e surface of the water.

When this occurs, the'dock-masterl 1 l bottom-or the vessel from one end'to the-- The relation of the parts of the dock when submerged are shown in Fig. 5.

By closing the relief-valve to sto the descent of'the dock the pressure of t 1e air, if any remains in the pontoons, may be brought up to the point which represents the hydraulic-head to which the dock has been sunk and will represent the pressure at which air must be introduced to displace the water.

The closingof the flood-gates is a matter of l ttle or no importance, as the pressure of air prevents any more water from entering, and ascheck-valves prevent the egress of the water by way of the flood-gates they may be left open or, an convenient time taken to close them. With the dock in this condition, the ship is warped into place and correctly located above the blocks. The dock-master then observing that he has a greater pressure of air in the main supply-- plpe 34 than is called for by the depth to which the dock has been submerged, opens the main supply-valve 35, (it bemg understood that the valves 37* are open.) The air is admitted to the surface of the water in all the compartments of the dock at an'equal pressure. Attention is called to thefact that there are no other valves and that the dehvery of an at an equal pressure is certain and cannot be interfered with, intentionally 5 or otherwise.

The only outlets from the separate compartments of the pontoons of the dock are those from the extensible and retractible outlet-delivery connections. These the dock- '1 oo master has previously leveled up, so that theyare the same distance above the surface of the water and all in plain sight along each side of the dock. A little consideration will make it clear that the pressure upon the 10 surface of the water in the chambers of the 5 dock must not only equal the hydraulic head of the depth of immersion, but that to deliver water from the outlets it must be as much greater as is necessary to raise it to I10 the outlets, and as there are no obstructionsvalves or otherwise-in these outlets they will all deliver water at the same time and to the same amount, and if it is even considered that due to some slight imperfection iiof construction one outlet may deliver water with a slightly-greater resistance than another, the system provides for a perfect and permanent correction of this by slightlylowering it relative to the others.

'lhe dock-master at first opens the main supply-valve only slightly, and is thus able to graduate the pumping to any desired amount. This is particularly important, as it is desirable to bring the dock gently against the bottom of the vessel, so as not to disturb the blocking which comes first in contact t with the vessel. Whenthe'doek has been brought up and pressed firmly against the placing the ship out of center.

other, the main supply-valve will be closed and the bilgeblocks drawn in under the bilges of the vessel in the usual manner. The main supply-valve will then be opened and the pumping continued. It may appear in a short time that one side of the dock is coming up faster than the other, caused by As soon as this is ap arent the dock-master has a perfect control 0 the situation. He can shut off all the pumping-power with one valve, or he can divert more of the pumping-power to the lower side by partially closing the deliveryvalve to the high side, or he can cause the outlets on the lower side to be lowered faster than on the high side, and any one of these methods will cause more water to be delivered from the lower side and will-bring the dock and vessel to an even keel.

As the vessel is raised the outlets are lowered by being retracted equally on each side,

which motion is very slow and deliberate,

never more than one foot in two minutes. The lateral horizontal plane of the dock and vessel will ordinarily be maintained by varying the rate at which the outlets on the oppo-' site sides of the dock are lowered. Under these conditions of the admission of air and control of the outlet of the water the dock will be raised until the deck is above water, when the vessel will be dry-docked and ready for the execution of any repairs or examination that ma be necessary. Attention is called to the fact that whenever the vessel is raised a part of the way or distance out of the water and the air-pressure gives out or fails from any cause the dock will not sink back. The only change will be that the water in the discharge-outlets at that time will fall back into the pontoonsthat is, the

dock is in no way sustained by the air-pressure, which acts with all the functions of a pump to remove the water from the pontoons of the dock.

When the ship is to be floated off the dock, the operation is as follows: The main supplyvalve 35 is closed. The relief-valve 35 and the valves 37 are opened. The flood-gates 8 are all presumed to have been closed before the air-pressure used in raising the dock was allowedto escape. The first operation is to open theTlood-gates the same as for lowering the dock light, it being taken into consideration that a less amount of opening will cause an equal rapid descent, for the reason that owing to the weight of the ship there will be more dilference in the levl of the water within and without the dock to cause the water to enter faster. When the deck of the dock. approaches the surface of the water, the flood-gates will be nearly closed, as previously described in the case of lowering the dock light, and in this case another precaution will be taken. It is presumed that the compartments have all filled evenly; but to test this it is only necessary to close the relief-valve to the atmosphere and turn on the air-pressure, it being understood that the outlets are all set at the same height, and if it is a fact that all the compartments are equally full water will appear at all-the disfilling can be made at any point in lowering the dock and ship and repeated as many times as desired. When the dock descends to the necessary draft to float the vessel and give I the necessary clearance above the blocks, the vessel can be warped out and the dock will be ready to be pumped up light, as the dock without the vessel is a very evenly-balanced structure, and as the pumping with air is a perfectly-balanced pumping system entirely under the control of one man the raising of the dock can be done in a period of time only limited by the capacity of the air-supply. v

Slight modifications of this method of pumping are required under the following circumstances: first, when the vessel draws considerably more water at one end than at the other; second, when the vessel is much shorter than the dock; third, when through injury or from other cause the vessel has a considerable listv which it is not practical to correct before the vessel enters the dock.

First; In this instance the procedure is the same until the dock is lowered to the depth necessary to take the deepest draft of the vessel and the vessel is in place over the blocks. The clearance of the vessel over the blocks may then be one foot at the stern and perhaps six feet at the bow. It is desirable that a vessel in dry-docking should take the blocks throughout her entire len th at as near the same time as possible; 0 accomplish this, it is only necessary to so adj 11st the discharge-outlets that water will at first be delivered only from those that are located at the end of the dock corres onding to the lightest draft of the vessel. his is done by raising those from which the discharge is to be retarded and then turning on the air-pressure in the usual way, when the dock will rise at one end only, and by regulating the air-supply to give a very gentle delivery the dock can be controlled and brought to an inclination longitudinally corresponding-to the keel of the vessel, and when this has been accomplished those outlets that have been raised are to be lowered until the water commences to flow from them; If this is done before the dock is raised against. the vessel, it is a parcut that water can be delivered from a l the Compartments with the dock at an angle, and

the dock can be maintained at this angle As soon as this has been done and before the vessel has been lifted any considerable distance'out of the water the dock and vessel should be leveled up by raising those outlets at the end ofthe dock that is farthest up, so as to stop the discharge of the water from them until the discharge from those near the other end have brought the dock to a level, When-these should be lowered until water will deliver from them. When this is done, it will be. noticed that they will deliver water before they reach the level ofthe other outlets. This is because there will be more waterin these compartments than in the others, and the diiference in the level at which they discharge is an exact measure of the difference of the water-level in the compartments. In raising the outlets toward one end it is not necessary that they should be all raised an equal distance, and by graduating them-carefully the pumping in each compartment can be made to exactly correspond to the inclination of the dock. In ordinary cases great accuracy in this respect is not necessary, as the stren th of the side walls is made such asto distribute a reasonable difference of water-level in the pontoons. When the dock and vessel have been brought to a horizontal position, the raising proceeds as described for the previous case. In lowering this vessel the dock is lowered in a horizontal osition until the vesselis well immerged.

efore there is any danger of floating at the lighter end the dock is glven the proper rake or. inclination by closing the flood-gates at the light end, and when the rake has been obtained th closed gates are opened and the a are drawn. Thin when vessel lowered parallel to her water-line until floated.

Second. When the vessel is shorter than the dock, it is desirable to locate her near one end. In this case the. rocedure is the same as in'the first case unti the vessel is in contact-with the keel-blocks and the bilge-blocks pumping is commenced it will be found that the end of the dock without the vessel will rise faster, and to correct this the outlets on that end will "be raised 'to retard or stop the discharge of water,- and repeated adjustments of these outlets will keep the dock and vessel in a horizontal osition. The gradual increased height at w ich these outlets will deliver water: will indicate the greater amount of water.

in thesepontoons over those on which the vessel rests. As soon as the vessel is raised entirely out of the water it will be found nee.-

'essary to pump all the compartments evenly,

and the outlets will be adjusted to do so. In lowering the vessel all compartments'are to be flooded evenly until the vessel takes the water, when the flood-gates to the light end of the dock are to be partly closed to hold that end back and keep the dock horizontal until the ship floats.

Third. When the vessel has a considerable list, in this case it is desirable to lower the dock for somewhat more clearance than is generally necessary, and when thevessel is approximately in position all that is necessary to bring the dock to the same angle of list is to admitair only to that side of the dock corresponding to the high side of the vessel. The pumping on that side only will soon list it until the angle of heel is the same as the vessel. The outlets on both sides of the dock should then be adjusted to deliver water at the same time. This will insure the dock rising without changing its angle of in clination. The vessel should then be carefully located and the pumping continued until the keel-blocks are firmly pressed a ainst the keel, when the bilge-blocks shou d be drawn and care taken that they are all in contact with the bilges of the vessel. The pumping is then continued and the outlets on the low side of the dock gradually lowered faster than those on the other, which will cause more Water to be delivered from that side; and the dock and vessel will be b11011 ht to an even keel. It will thenbe foundti at the outlets on the side toward which the vessel heeled will have to be kept lower to kee the dock level, and this amount correspon s to the difference of the weight of the vessel pn opposite sides, which was the cause of the ist.

During any or all of these operations, at any time the exact relative level of the water in the compartments can be determined by noting the relative level of the outlets when they deliver water. I

WVhile my invention is shown and described as. applied to a floating dry-dock of the well-known Rennie type, it will be understood that it is equally applicable to any other ty of dock, either solid or sectional, and Whi e I have herein shown and described the air-producing. means as located on the shore it is evident that it may with equal facility be located on the dock itself or any other floating structure.

I do not desire to be understoodas limiting myself to the specific details of construction and arrangements as herein described and illustrated, as it is manifest that variations and modifications may be made in the features of cons tiaction and arrangement on the adaptation of the device to various conditions, of use Without departing from the spirit and scope of my invention and improve-, ments. I therefore reserve the right to all cut, is

such variations and modifications as properly fall Within the scope of my invention and the terms of the followin claims.

Having noW descri ed my invention, What I claim, and desire to secure by Letters Pat- 1. In a floating dry-dock Water-inlet means, unrestricted Wateroutlet means,

means for supplying air under pressure to the Various compartments and means for.- controlling the expansion of the air in said I compartments while the dock is:-ris1ng, sub-- stantially as described.

2., In a floating dry dock Water 1n 1et means, unrestricted. Water l outlet means,

means for supplying air under pressure to the stantially as described.

4. In a floating dry dock Water inlet means, extensible and retracti ble Water-outlet means and means for exhausting the Water therefrom, substantially as described.

5. In a floating dry-dock, pontoons, Waterinlet means, extensible and retractible Wateroutlet means therefor, and means for exhausting water therefrom, substantially asdescribed.

6. In a floating dry-dock, pontoons, Waterinlet means, extensible and retractible Wateroutlet means, air-inlet means and means for controlling the introduction of air, substantially as described.

7. In a floating dry dock, Water inlet means, extensible and retractible Water-outlet means, and means for simultaneously extending and retracting said outlet .means,

substantially as described.

8. In a floating dry-dock, Water-,inlet means, extensible and retractibl'e Water-outlet means and means for independently extending and retracting said outlet means,

means for extending and retracting said outlet means and means for exhausting Water therefrom, substantially as described.

11. In a floating dry-dock, Water-inletdescribed.

' -means, extensible and retractible Water-out' means, pontoons, extensible and retractible Water-outlet means therefor; embodyin'gtel vesoopic sections and means for extendin and retractingsaid outlet means, substantia was '13; In a floating dry-dock, water-inlet means, ,pontoons', extensible and retractlble escopic sections, and means for independently extending and retracting said outlet means, substantially as described.

14. In a. floating dry doclt, water-inlet means, pontoons, extensible and retractiblewater-outlet, means, embodying telescopic sections, means for simultaneously extending Water-outlet means therefor, embodying teland retracting said outlet means, air-inlet means, and means for controlling the introduction of air, substantially as described.

15. In a floating dry-dock, Water-inlet means, pontoons', extensible and retractible water-outlet means therefor, embodying telescopic sections, air-inlet means, and'means for controlling the introduction of air, substantially as described.

16. In a floating dry-dock, pontoons, extensible and contractible water-outlet means therefor, embodying telescopic sections, means for independently extending and contracting said outlet means, air-inlet means, and means for controlling the introduction of air, substantially as described.

17. In a floating drydock, water-inlet means, and extensible and retractible Wateroutlet means always extending above the surface of the water floating the dock, substantially as described.

18. In a floating dry-dock, Water-inlet means, Water-outlet means always extending above thesurface of the Water floating the dock, means for supplying air under pressure a therebycontrolling the rising of the dock,

substantially as described.

19. In a floating dry-dock, pontoons, water-inlet means, and extensible and retractible Water-outlet means always extending above the surface of the Water floating the dock, spbstan tially as described.

20. in a floating dry-dock, pontoons, Wa-

ter-inlet means, Water-outlet means always extending above the surfaceof the water floating the dock, means for supplying air under pressure to the Various compartments and means for controlling the ex ansion of air in said compartments While t e dock is rising and therebyeontrolling he rising of said dock, substantially as described. a

21. In a floating dry-dock, pontoons, wa-

ter-inlet means, extensible and retractible trolling the introduction of air, substantiallyas described.

23. In a floating dry-dock, water-inlet means, extensible and retractible Water-outlet means, air-inlet means and means for control the exhaust of air substantially as describe v 24. In a floating'dry-dock the sidesof which consist of Water-tight chambers, wa-

ter-inlet m'eans, unrestricted Water-outlet 20 means, means for supplying air under pressureto the various compartments and means for controlling the expansion of the air in said compartments While the dock is rising, substantially as described.

25. In a floating dry-dock the sides of ,which consist of water-tight chambers, pontoons, water-inlet means, unrestricted Wateroutlet means, means for supplying air under pressure to the various compartments and means for controlling the expansion of the air in said compartments While the dock is rising substantially as described.

In testimony whereof I have si ned my name in the presence of two snhscrihing witnesses.

' WILLIAM moms DONNELLY.

Witnesses: 7

JOHN R, Sporr, I GEORGE Ersnnssmm

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