USRE11873E - Caisson - Google Patents

Description

nu. Imm. neissued Nov. 2o, |900.

' w. H. McFA'oDEN.

CAISSON.

(Application filed Oct. 5, 1900.)

I4 Sheets-Sheet l.

1N: NaRRls Ps1-1': 's ca., WASHINGTON. ofc.

nissued Nav. 2n, |900.-

W. HA. MCFADDEN. cAlss'oN. v (Application filed Oct. 5, 1901.).'1

I4 Sheets-Shen 2.

th's nroRms Perses Reissued Nnv. 20, |900. W. H. MGFADDEN.

N0. man.

C A S S D N (Application filed. Oct. 1900.1

I4 Sheets-Sheet 4,

| I I l i i l l 1HE Noxms Pannes co., wAsHmm'uN, 9. c,

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loiro N sz i wrrnEssEs':

1H: Nomezs persas cn., w/lsmNamN. n. c.

No. ,873. y Ressued Nov. 20, |900.

W. H. MCFADDEN. Y

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THE-NCRRIS PETERS w., WASHINGTLN, D. C.

neissued Nov. 20, |900.

w. mmcrAnnEN.

, CAISSON.

[Application mcd Oct. 5, 1900.;

14 shuts-sheet 7 w l IIWNTOR Anv.

1HE Nome/s PETERS ca.. wnsHmmaN, n. c.

Reissed Nov. 20. |900.

W. H.' MCFADDEN.

CAISSON. Appucacinn mcd oct. 5, 1900.)

{4,Sheets-Sheet 8.

FISH.

INVENT R Att'y.

mE nomas PEJ'ERS co., wAsHmmaN. D. c.

No. man. neissued Nav. 20, 1 900, w. H. MGFADDEN,

' CAISSON.

(Application :und ad.; 1900.

I4 Sheets-Sheet I0.

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No. man.

C A I S S 0 N (Application tlcd Oct. 5, 1900 I4 Sheets-Sheet il.

` Atty- 1HE Nmams PETERS cu', wAsmNaraN, a. c.

vNo. ||,a73. f Reissued Nov. 2o, 1900.

w. H. McrAnnEN. I

- CAISSIIN.

'Application filed Oct. 5, 1900. I

14 Sheets-Sheet l2.

rn: Nouk/s PETERS coA, wAsmNaroN, n. c.

WI masses:

wf H. McFAnnEN.

i.' CAISSON.

(Applicazion med ocn, 1909.-]

nrs Nnmus PETERS co., wAsHmcroN, n. c.

Re'issued Nov. 2o, |900. l

| l l l I l 'l l l l l Reiss'ued Nov. 20, |900.

w. H. MGFADDEN.

CAISSON.- Y

(Application filed Oct. 5, 1900.,

I4 Sheets-Sheen I4.

THE NoRRls PETER: ca.. wAsmNcroN. n, c.

`on the float.

showing the caisson entirely detached from t UNITED STATES PATENT OFFICE.V l

IVIIILIAIVI II. MUFADDEN', OF PI'ITSBURG, PENNSYLVANIA.

CAISSON.

SPECIFICATION forming part of Reissued Letters Patent No. 1 1,873, dated November 20, 1900.

V Original No. 656,850, dated August 28, 1900. Application for reissue iled October 5, 1900. Serial No. 32,103.

T all, whom, it irl/ty concern/.-

, 13e it known that LWILLIAM H. MCFADDEN, a citizen ofthe United States,residing at Pitts burg,y in the countyof Allegheny and State of Pennsylvania, have invented or discovered certain new and useful linprovementsin Caissons, of which improvements the following is specilication. l,

The invention described herein relates to certain improvements in apparatus for dredging and removing earth, stones, dac., from the bottoms of. rivers, lakes, dac., and also for the leveling up of the' bottoms oi' such bodies of water or for clearing or cleaningthe same, as desired. Y

Among other things the invention has for one object a construction of caisson and hoisting 'mechanism connected therewith whereby the continuons removal of material from the caisson may be elfected without in anyway -interrupting or disturbing the duid seal,

whereby a certain predetermined pressure can be maintained in the caisson to prevent the ingress of water. lt is a further object of -the invention to provide for an extension of the caisson, so as to render it available atditferent depths.

The invention is hereinafter more fully describedand claimed. p v In the accompanying drawings", forming a part ofA this specification, Figurel shows a float having' my improved caisson connected to one end thereof and also provided with suitable mechanism-such as dippers, bucle ets, and clam-shells-for the removal of dirt, Sac., from the bottom of the river, dac., and mechanism ior'operating such devices. Fig. 2 is a top plan View ofthe same. Fig. 3 is a View in side elevation, showing the caisson separated a short distance from the float or scow, but having suitable connections by pipes' to pum ps and air-com pressors located Fig.' 4c is a viepr in elevation,

he scow or lio-at and having the pumps and compressors mounted thereon. .Fig 5is a View in elevatiouof the upper portion of the caisson, showing the air-chamber and-a .portion of lhe superincumbent tank, whereby weight may be imposed on the caisson for i'orc.ing,the latter down, as hereinafter de' scribed. Fig. o isa sectional elevation of the upper portion of the caisson, the plane cf section being'indicated by the line VIVI, Fig. 7. 'Fig."7 is a sectional plan view, the plane of section being indicated by the line VII VII, Fig. 6. Fig. Sis a sectional detail view `,illustrating the brake mechanism for the bucket-hoist. Fig. 9 is a sectional detail View on` a plane indicated bythe line IX IX, Figs.

6 and 7. Fig. l0 is a sectional elevation through the air-chamber, locks, andmotor chambers on a plane indicated by the line X X, Figs. o and 7. Fig. 1i isa-view, partly in section and partl57 in elevation, of the discharge-conduit on a plane indicated by the line XI XI, Fig. 7. Figs. I2 and IB are detail views of the discharge-conduit. Fig. I4 is a sectional plan on a plane indicated by line XIV XIV, Fig. l2. Figs. 'l5 and 16 are sectional 4elevations of the lower portion of the caisson, the planes of section being indicated, respectively, bythe-lines XV and XVI, Fig. 1 7.v Fig. I7 is a sectional plan View on planes indicatedl by the lines XVIII XVIII, Fig. 15. Figs. 18 and 20 are views in elevation, and Fig. I9 is a top plan view showing the manner of guiding and supporting the upper` part of the caisson as against lateral movement and also supporting the air-chamber and submerging-tank While adding or re' `scow l is provided et one' end with a recess in which is located the caisson, to be hereinafter described. On the float and around the edges of the recess are securedposts and u p rights 2, whichserve as lateral supports and guides for the caisson in its vertical movements. When the caisson is resting upon the bottom, the surface movement ofl the' Water wi ll impart an oscillation to the float or sc'ow,

which would tend if vthe posts or uprights bore directly on'the sides of the caisson to sway the latter back and forth. 'In order to permit a certain amount of movement ot' the scow independent of the caisson, bearingboards are movably mounted on the frame, ofv which the posts 2 form appart, their lower ends' resting upon cross-timbers 4, as clearly "shown in Figs. 18, i9, and 20. These boards are pressed against the sides of the caisson by means oi' springs 5, having one end se- IOO Iov

`vcured to the frame, while their opposite ends it. is desired to Shift the iio'at -arid caisson or to insert or remove sections thereof supporting-arms 7 are pivotally mounted upon the scow in such relation to thenormal position ofthe caisson that the arms can be swung in under lugs 8, formed at the -lower end of the. air-chamber.

--The caisson consists, essentially, of au airchamber, .a submerging-ftank E, arranged.

' ber and working chamber, and a dischargev conduit, as will be hereinafter described.

As shown vin Figs. 5 to 8,' the air-chamber consists, substantially, of a metalshell'having on opposite sides double walls 9 and 10, each provided with doors 11 for the ingress and egress of the workmen. These doors are constructed in the usual o'r anysuitable manner and provided with suitable locks,- wherev 'by theymaybelirmly secured in a closed lposition and when so secured heruietically seal the spaces or chambers A between vthe dou-` ble walls. Within chambers D, formed above the air-locks and provided with doors 11, are placed electric motors 12 and 13. lPlhe mot-or 12 is employed for operating, through suitable gearing and counter-shaft 12% Athe verticalI shaft 14,' extending down to or toward'- the lower end of the caisson andemployed forshifting the digging-bucket, as Will-herelinafter be described. The motor 13 'is convv45.

nected by suitable gearing to the shaft v15 within the mainchambe'r 'Brandon said shaft is secured a`drum 16 for hoisting a bucket 17. VThis bucket can be used with cover' 22 of the discharge-box 23.

. the conveyer or digging.bucketsfhereinafter described, for the removal of. dirt, duc., from' the bottom of the caisson, but is generally employed for lthe removal of large stones or other substances which would not pass readily through the discharge-cond uit. The rope 18, by which the bucket is raised, passes around a guide-pulley l9, secured to the top. of' the air-chamber. B, and around a pulley 20,- mounted on ain arm 2l, attached tothe lid or This discharge-box extends through the bottom of the air-chamber into a receiving-chamber 24, secured to the underside of the air-chamber. The lid 22 when in normal or closed position forms a tight joint with 'the edges of the box, so as to prevent any material loss of air. As

thev bucket is` raised the bail thereof will strike against the arm 2l, so as to lift the lid For the purpose of supporting` lform of lock 32.

22 on t-hercontinued upward movement of the bucket, which as soon as it-reaches discharge position, as shown by dotted lines iuFig. G, will tip, its holding-lock beingreleased, and discharge its contents into the box 23. On the shaft 15 is secured a disk 25, having a strap 26 arranged around it, one end of said strap being connected toa suitable stationary support, while the opposite end is con` nected t'o-0"ne arm of av bell-crank lever 27. The opposite` end of this bell-crank lever is connected to a suit-able shifting mechanism, which preferably consists of a solenoid 28, having its core'connected to thelever. The circuit of Vthis solenoid is controlled by a switch or controller, which yalso'coutrols the current tothe motor 13, so that whenl the c'urrent-is cut oif from the motor the circuit of the solenoid will beclosed, so that -the core of the latter will beshifted to apply the brake to the shaft/15, and thereby hold.` the bucket 17 at any desired elevation. As soon as the contents of the bucket have beendischarged into the box the controller of the motor 13 and -solenoid 28 is reversed, so as to break the circuit of the solenoid, allowing the bucket to drop,and thereby permit the closing of the lid 22.

In order vto removedirt,l stones, dac., from' the receiving-chamber4 24 and also toprevent the loss ofair when the lid22` is opened, as v 'before stated, the box, 24 forms a part or en B. This pressure or head within the pipe 30 is produced and maintained by reducing the Odischarge-orifice beyond the carrying capacity of the lpipe and forcing ina supply of water `in excess of the delivery capacity of such orifice; This stream of Wafer not only serves to remove dirt, Jac., from the box 24, but also as a' sealto prevent the escape of air from the air-chamber when-'the lid 22 is opened. In case'the rocks, &c., discharged `into`the chamber 24l cannot be removed through the pipe 3U the box -is provided with a removable bottom 3l, hinged to one side of the box andheld in position by any suitable After the lid 22 has been closed the bottom 3l can be opened and the rocks. or other substances removed without any loss of air, except suchsmall volume as may be contained within the boxes 23 and 2,4. The discharge-pipe 30 is also provided with a removable section 30 for the removal of any substance which cannot be removed bythe water.

The tunnel or tubular shaft connectingthe air-chamber with the working cham ber at the lower end of the caisson is formed ot' a series of sections 33,-provided at their'ends with IOO inwardly-projecting flanges 34, whereby they may be bolted together and to the under side of the air-chamber and the top of the work- VlO connected together by couplings or,

ingl chamber C. Each of thesjesections is provided with braekeis 35,having their outer ends suitably shaped lo form bearings forv the sections of the vertical shaft 14. Each of these 'shaft-sections is inade of the same Ilength as the Sections com posing the tunnel ,or tubular shaft and is' held from 'vertical movement byeollars 36,seeured to theshait-- sections 14 and resting on the brackets, as shown in Figs. 7, 15, and 1G. `Vlrheu a section SS is introduced into the-tubular shaft or tunnel, the driving-shaft sections 14 are thereby forming a continuous driving-shaft for the outireleugth of the caisson.

As shown in Figs. 151 16, and 17, the workshell open at its lower end .and provided at its upper end with 'flanges 38, whereby it may be bolted to t-he lower section of the conneetlugr-tunnel.` Within this working chamber is arranged the loirer .end of the dis# charge-conduit 39, which enters through a stuiiingbox 40 in the uppei end of the'working chamber at one side of the tubular shaft or tunnel and is capable of movement up and down in said chamber, as will be hereinafter described. The conduit is held in position in the working chamber by vertical guides 41, to which the conduit is vattached by means of bolts 49 as shown in Fig. 17.

The lowcrend of the conduit is closed, butis provided with an upwardly-projecting branch 43, into which the 'dirttobe removed is discharged by buckets 44 -on an endless belt passing around ,a driving-pulley 45 and a guide-pulley 4o. The pulley 45 is mounted on ashaft which .has bearings in the sides of the' turning'head- 48. Y The bearings f orthe shaft of the guide-pulley-46 are -made movable on the side plates 47, so that by the .turning o t the adjusting-screws or nut 49 the tension of thev belt carrying the buckets can be regulated as desired. The turning head is provided at its upper end with a stem 50,' extending through a bearing 5l, formed at the ,end of a bra'cket secured to the wall of the At its lowerend the turn working chamber. ing head is'provided with a tubular stem 52,

litting loosely into the upper end of the branch pipev 43, as shown in Fig. l5. As the .parts are so'proportioned that the upperend' of the branch-43 is nearlyin the center of the working chamber, the frame carrying the buckets 44` can be turned through an are of nearly three 'hundred andy sixty degrees, or

' from oneside of the discharge-cond uit around tothe opLmsite side. The side plates 47 are pivotally mounted upon the shaft 45, sethat .their lower ends can beimoved out and in from near the center oi' the working chamber to close proximity to irsouter wall.' The frame carrying the buckets44isheld in Working position by means of yokes 53, engaging a band 54,- seeu red to theside ot' theworking chamber. These yokes 53 are free to slide around on the band and are connected to lhe side plaies 4711),' means oi' chains and springcushions 55. 'lhese spring-cushions will permit the lower end of the frame carrying the buckets 44 to yield slightly in oase the buckets should strike against a. rock'or other unyielding substance. 'On the helft .45a is seeureda bevelcd'pinion 55, intermeshing with the cor- *respond ng pinion 'on the short shaft 57,mountf ed in suitable bearings secu red to theturning-v head 4S. lhis/short sha t irs connected to the lower section of .the d ri vin glshaft 14 by vmeans of an extensible shaft 58, consisting of'a tubular portion for the receptionfof a solid por- Ytion, as shown in Fig. 16, saidfparts being keyed together, so that theyare. freeto move along each' other, but. are caused to rotate one with the other. The endsof' this extensible section are connected by universal -joints 59 to theA driving-shaft 1L and the short shaft 57, carried bythe turning head 48.y This eon''' struction permits of the raising and lowering of. the turning head and'the parts carried. thereby and also the lateral. shifting of such 'parts withodt interfering ,viththe'pperation i oi the buckets. The turning heal-1. an d the parts carried thereby can be raised or low' ered, as required, by an y suitable means- -v sucli, for exam ple. `as that shownconsistingv of a rope 6U, connected to the stem 50 of -the turni ng head an d passingaround guide-pulley 61 and having its opposite. end connected to a suitable windingdrufm 82, mounted on the side of the working chamber.

The discharge-conduit, which passes up alongside of the tubular shaft or tunnel, is formed'of a series of sections of a length preferably equal to the sections of the' tunnel heretofore described, said sections'being provided with flanges, whereby theylm'ay be corr' nected together, as clearly shown in Figs. I2, 13, and 14. of such a length that its upper end will be above the level of the water in Iwhich -work is being performed. The conduithead 63 is ar ranged in a frame b, which is' preferably independent of the coudnit'and is 'detaehabl'y secured on the air-chamber orthe section of the snbmergingtank immediately above the same.- The conveying-buckets 64, which are carried by an endless chain formed of separable sections, are arranged within the conduit and head. This chain passes around a driving-pulley 65, mounted on the shaft bo, passing through the' couduit-head, and a pulley 67, mounlted on the shaft 6B, passing through the lower end-of 'the conduit. Thel frameb, carrying the conduit-head, is provided with gui "1e-wings 63, arranged to move in guides d, secured in a recess in the lower end ofthe' subnierging-iank, and is provided at its Sides with lugs 70, recessed for .the reception of nuts, through which pass threaded rods 7-1, said rods being driven through suitable gearing by the hand-wheel 72. Byrhe rotation of these rods the conduit-head can be raised or lowered, thereby adjusting the tension of the bucket-chains, as required. VAs-'the buck- This conduit ispreferably made i 81, so that by pulling on the rope 80 the dis- 83, the doors of ,the air-lock having been into the shaft, so as to adjust the digging a scow or other reservoir located in co'nven' chamber, as shown in Figs. ll and .15.

'of the river or other body of Water. Water is conduit 39, and the pipe 75 until the level of the Water inthe caisson reaches the level of f great, the'sur'plus can be removed by oper- `maintaining the water therein at a constant ets pass around ,the driving-pulley the-contents are discharged through the nozzle 73 of the head 'into a receiving-basin 74, which forms an enlargement of the pipe 30, hereto- .fore referred to, through which aconstant stream of Waterunder pressure is maintained. The dirt, &c.,vis removed from the basin 74 by this stream-of water and discharged into ient proximity to the discharge-nozzle of the basin. A pipe 75 has its lower end connected to the conduit at a point above the working The upper end of this p ipe is held above the level of the Water in which the work is-being performed by means ot' a rope 7b, connected to a drum 77- on the shaft 78. This shaft, as shown in Figs. 6 and 7 passes into th.e'work` ing chamber B, and is provided with a driving-drum 79,'aronnd which is passed a rope 80, extending down into the working chamber, where it is attached to a winding-drum charge end of the pipe 75 can be raised or lowered, as required.

Inoperating myimproved caissomthe scow having been secured in position by any suit-v able means, the caisson is allowed to move down untilits lower end restsV upon the bed then pumped into thesinking or snb'merging tank E, on top of the airchamber B, through the pipe ,82, said tank being formed in sections,asshown, so that a larger or smaller body of water may be employed, as required, Y

to sink the caisson. Air is now forced into theair-chamberl and tunnel through the pipe closed and sealed. As the pressure accumulates within the caisson any water therein will be forced outthrough the branch 43,

the opening of the branch 4 3., Workmen can now enter the air-chamber and descend mechanism iu the working chamber. .If thel depth of water in the Working chamber is too ating the buckets 44, which will raise the water from the lower end of the caisson and discharge it into the pipe 43, the p ressure of. the air on the water in this pipe and conduit level. By the operation ofthe buckets the dirt is removed from within the caisson/and discharged into the branch 43, down which it will pass to the lower end of the conduit, where it is caught-by the buckets 64 and raised np and discharged into the basin 74. The upper end of the conduit is maintained above theA level of the water in which work is being performed, 'so that none of the dirt contained in the buckets can be washed therefrom-and in order that a pressure in excess of that necessary to balance a column of water equal to the depth of Water in which V'11,8'73 i l work-'is being done may be obtained,litide:

contains the'column of water connected with.

the conduit. By increasing or' decreasing the height of this col-umn 'of water contained in thefpipe 75 the pressure' in the chamber can be regulated-that is tov say, by increasing the height of this `v vater column a greater pressure can be maintained. In order to replace any water removed: bythe buckets 64 and insure avcolumn of water within the pipe 75 and in the conduit oi sunicient height to balance the air-pressure within the caisson, a

supply-pipe 84 isarranged so as to discharge water into the conduit, as `'shown in Figs. 5,

7, and l1. When in operation, a su-fcient quantity of waterin excess of the amount removed'by the buckets 64 is discharged into the conduit by the pipe 84, the surplus escaping from the upper end of the pipe 75.4 In case themanwithin the working chamber- -noticesa dropping dowp of the water inv thebranch 43 he immediately raises the; pipe 75- bya pull on the rope 80,thereby`rcquiring an increase in the height of the water columns in the conduit and'pipe 75 before any further escape of water -from the latter-can occur. This increase in height' ofthe water columns will-counterbalance the increased pressureA in the working chamber, which causeda,A low-- ering of the water in lbranch 43,

,When it is desired to add sections tunnel and conduit, the entire caisson vmay be raised by means ot' chains 85., connected'to the working chamber, as shown in Figs. 'l'a'ndf 15, assisted by the block and 'tackle on the frame surrounding the'caisson, ,until the shoulders 8 on the air-chamber areabove the supportingbracket 7 These brackets are then turned in to support the caisson in its raised position. The bolts connecting'the uppersection ofthe tunnelto' the air-cham'- ber and the 'upper section 39a of the conduit with the adjacent lower section are .then fre? moved. The section 39a is then'raised' by the screws 87, connecting said section with the .I

to theconduit-head, a sufficient distance to permit.

Aof access to the endless chains carrying the buckets 64. A` rod 8.8 is next slipped across the end ofthe conduit and through the chain, as shown `in Fig. 13,.to prevent the lower'por- 'tion ot' the latter from dropping down-and the 'The r chains disconnected above the rod. working chamber, with the tunneland conduit, is lowered suiciently to permit-of the insertion of new sections in the tunnel and the conduit. New sections are now placed in position and bol-ted tothe tunnel and airchamber and on the upper end of the conduit. An additional section of conveyingchain is also added and. connected to those already in position. The caisson isvnow raised,so as to permit of thetnrning in bf the'supporting-V ybrackets 7, andk then lowered down to position. Tn lieu of raisingthe whole caisson, as "stated, and the disconnecting of the parts the lattermay be disconnected and the airchamber, tank, conduit-head, and upper section `39a raised by the block and tackle S6 and the new sections inserted.

As shown in Figs. 3 and 4, the scoworfloat 1 may be moved away from the caisson after .the latter has been lowered onto the bottom, the pumps on the float being connected tothe air-chamber, tank, and pipes 30, 82, 83, and 84 by. hose or other extensible pipe connecriver or other body of water.

'or scow is' moved away from the caisson, the 'latter should be held from tipping by guys As shown in Fig. 4, the pumps 89' and 90 for supplying air to the caisson and water to the tank E maj,r be located on a'platform 91,

secured to the caisson, 'and the pipes 30 and 84 connected to the tank, thereby rendering the caisson entirely independent of the float after it 'has been lowered on the bottom of the' When the oat 91, extending to posts or other suitable anchors.

As shown in Figs. 1 and 2, the fioat or scow y may be` provided with a power-dipper92,

' clam-shells 93, and buckets 94 for ordinary vdredging operations` 'I claim herein as my invention 1. In a caisson, the combination of an airchamber provided with an airlock,'an openendedworking chamber, a tubular shaft or tunnel connectingthe air and Working charnbers, formed of separable sections, and a submerging-tank arranged on the `air-chamber, substantially as set forth.

2. In a caisson, the combination of an air- `chamber, a Working chamber, tubular shaft or 'tunnelcon-necting the air and Working chambers,and a Water-sealed discharge-openforth.

ing from the air-chamber, substantia In a caisson, the combination of an aircham ber, a working chamb er,a tubular shaft or tunnel connecting the air and working cham bers, a discharge-box in the air-cham ber and extending through the wall' thereo`,a pipe -working chamber having an open `lower end,

and awater-sealed U-shaped discharge-coudnit having one arm opening Within the working chamber and the other arm extending from the workin-g chamber to a point above lly as set.

the level'of the water, substantially as set ftllill. y I.

6. A. caisson, having .in combination a working chamber having au open lower end, a water-sealed IU-shaped discharge-conduit having one arm opening within the Working chamber and the other arm extending from the Working chamber to a point above the levelof the water, and a hoisting mechanism operating in the U-shaped conduit, substantially as set forth.

7. A caisson, having'in combination, a

working chamber havng'an open lower end, a water-sealed conduit extending .from the Working `chamherfto a point above the level of the water and means for varying the height of the water column controlling the water seal, subsrantially as set forth.`

8. A caisson, having in combination, a working chamber having an open lower end,

`a discharge-cond uit extending from the Working chamber' to a point above the level of the Water and provided, within the working chamber, with a receiving branch having an open upper end and means for maintaining the water within the conduit at a height not less than the level of water outside of the conduit,

substantially as set forth.

9.v A caisson, having in combination, a Working chamber having an open lower end,

a discharge-conduit extending from the working chamber to a point above the level of the I water and provided'with a receiving branch, a turning'head,I a conveyer connected to said head, said parts being so arranged that the material from the conveyerwill be discharged into the branch in all positions of the turning head, substantially as set forth.

10. A caisson, having in combination, an air-chamber, a working chamber, a tubular shaft or tunnel connecting-the air and Working chambers, a discharge-conduit extending from the working chamber to a point above the level of thejwater, a conduit-head movably mounted on the air-chamber, an endless chain provided with buckets arranged within Ioo l IIO the conduit and head, a receiving branch having an open upper end connected to the conduit within the working chamber, and a .digging mechanism movably mounted on the receiving branch, snbstantiall y as set forth.

-l1. A caisson, having in combination, an

airchamber, a working chamber, a tubular shaft or tunnel' connecting the air and working chambers, formed of' separable sections, a discharge-conduit formed of separable sections extending from the working chamber to a point above the level of the water, and provided With a receiving branch Within the working cham ber, a digging mechanism with- 'in-the working chamber, a power-shaftextending from the air-chamber to the working chamber formed of separable sections mounted in suitable bearings Within the sections of the tubular shaft or tunnel, substantially as set forth.

"12. A caisson, having` in combination', an air-chamber, a, Working chamber, a' tubular vided with guiding posts or supports, a eais-' son arranged between said supports, means shaft or tunnel connecting the air and -work-A for vraising the oaisson'and supports movably ing chambers, a Snbmerging-tank arranged on the air-chamber, a, discharge-box arranged' -Within the air-chamber and extendingthron gh ro tially as set forth. i Y

13. The co'rnbinationof a, neat o1-seen1 promonnted on the float for holdingthe caisson in raised position, substantially as set forth. In testimony whereof/.I have hereunto set my hand. v`

WILLIAM H. MCFADDEN. Witnesees:

DARWIN S. WO'LCo'r'r, l F. E. GAIT'HER.

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