US1475385A - Subaqueous sound-signal transmitter - Google Patents

Description

Nov. 27 1923, 1,4752385 H. HEH-r E'r AL SUBAQUEOUS SOUND SIGNAL TRANSMITTER Filed May 28, 1914 7 Sheets-Sheet l a mae f www; smv

Nav; 27 1923.` v 1,475,385

. H. Hl-:lcH-r ET A`L suBAQuEous SOUND smrm. TRANSMITTER Filed may 2s, 1914 7 shts-sheet a Nav. 27,1923. 1,415,385

H. HECHT ET AL SUBAQUEoUs sounn SIGNAL TRANSMITTER Nov. .21,1923` 'Y 1,475,385

H. HECHT ET AL SUBAQUEOUS SOUND SIGNAL TRANSMITTER' Nov. 27, 1923. V 1,475,385

H; HEcl-n' E1' AL suBAQuEoUs sounn SIGNAL TRANSMITTER Filed may 28, 1914 "7 sheets-Sheet 5 H. HECHT ET AL SUBAQUEOUS SOUND SIGNAL TRANSMITTER Filed May 2s, 1914 #sheets-sheet e Nav. 27,1923. f 1,475,385

H. HEcl-rr ET AL SUBAQUEOUS SOUND SIGNAL TRANSMITTBR y vFiled May 28. 1914 '7 sheets-Sheet v i, L9? l Patented Nov. 27, 1923.

UNITED ls'rArir-:s

PAIENrorF1cE-] HEINRICH IIEcIIT AND FERDINAND SCHENKELBERGER, or KIEL, GERMANY.

SUBAQUEOUS SOUND-SIGNAL TRANSMITTER.

Application mea May 2s, 1914. .seriaiiNa 841,473.

To all 'whom t may concern.'

Be it known that we, HEINRICH `HECH'I and FERDINAND SCHENKELEERGER, subjects of the German Emperor, amd residing at Kiel7 in Germany, Feldstrasse 65, respectively, Hansastrasse 76,' in the Kingdom of Prussia, have invented certain new and use,

r transmission, and to secure a more-'favorable relation between the amount of energy eX- pended and the distance of transmission.. The invention is based upon the recognition ofl the fact that the distance to which the sound produced by a subaqueous sound-signal transmitter is transmitted is reduced when gas or air contained in the sound carrying medium is dissociated or eliminated from the medium at the points in thesignaling devices where the sounds are produced.

F rom this discovery a. rule for building liquid operated signalling devices `may be deduced. This rule isthat either the liquid used in the signalling device for sound production-should contain no dissociable or dis,`

chargable gas; or the signalling appliances should be built so thatvany dissociable gas will not be discharged at the points in the signalling devices where the sounds are produced. AIn this latter case what is. required essentially is that the liquid substantially lacks free gasor expressed in janotherway substantially retains any lgas containedin it. A feature of this invention consists inthe arrangement and construction of the means by which the operating fluidis 'conducted in the sound producing device. `Another Jfeature consists in a special arrangement and constructionA of the transmitter; and another feature involves the useof special air separating devices. AV combination of all of these features maybe used tofaccomplish the desired effect but, o;t .coursecasesj may arise in which one of these. features, alone 4-Inay be found to sufice.

.'-In the case of diaphragm transmitters, submarinesound bells andr similar kinds of transmitters, in which no flowing water is employed for-'producing sound,it is sufficientfifjan amply large and deep tank be employed, `into which the sound transmitters are lowered and which isv filled .with

in 'itselfvfree from gas.

If ,thel transmitter is pl'aced'in water and provisionismade for an easy renewal of fluid which-has been previously freed or is the same at short 'intervals it is not neces-V saryto Vcompletely separate it from the outer water but it will sufiice if the gas-less or comparatively gas-less water -in the neighbourhood of 'the transmitter is soarranged that-it mixes only slowly with thev outer water.lv Noris it necessary to provide packings for excluding` the air, Vas the permea-v 'tion-by air of a fluid freed 'from air proceeds but slowly and the permeation process will be especially sluggish wherethe air has to` penetrate to considerable depths. A

' ackinv `or 'air eXcludin means will however be advantageousin anycase and it will be necessary when fluids are employed which are-naturally free ofgas in o-rder to prevent them Vfrom mixing with the external medium. L 1 Y In the case of transmitters which are operated with flowing water or some other flowingliquid, the-working medium em. ployed will preferably be a liquid that is naturally free from gas or is at least'poor in gas. n this case it is desirable to provide for a continuous circulation thereof. The operating mediumranthen be easily'kept fora longtime free from gas 'by making the conduit 'in which "theoperating medium circulates impenetrable Vby` the exterior mediumi y*As a liquid naturallypoor in gas7 oil for example, would come under consideration. For the purpose of freeing aliquid from gas artiliciallythe liquidcOntaining `the air or gas. may first fb@ f converted l into an emulsiony like mixture of gas andvivater, and this mixture then be separated into its constituent parts. rThe production of this mixture may bo effected in various Ways. Use may be made of sudden variations in the cross-section of a conduit or conduits through which altering their dimensions Yand other con-- structional conditions.

When once such a mixture of air and gas is present, there is no great difficulty in separating this mixture according to its constituent parts by suitable measures.V

Several forms of deaerating devices, such as above-mentioned, are illustrated in the drawings, and will be described more in detail hereinafter.

In order to r'prevent the dissociationof gas from the operating liquid at or near the point the sound producer, such as a siren 'for ex" ofthe signalling device Where Vthe sound is produced it is necessary to so construct the sound producing device, for example the 'si'- ren, that no sudden expansion of the jet of liquid takes place at or near the point mentioned. This'sudden expansion would result in a decrease of the pressure to vvhich'the liquid is subjected and in a consequent change of its degree of saturation and this Would enable the dissolved gases to dissociate themselves from the fluid. 1 The means by which the said sudden expansion of the liquid at or near `the point Where the sound is produced, is prevented, consists in a construction' of ample, which ensures the greatest possible intimacy of contact between' the moving and stationary parts. This construction forms another feature of the present invention;

It is also important to prevent decrease of pressure of the fluid by suctionail action in the intake pipe of the force pump that delivers the Water to the siren. The means used for accomplishing' this and Which forms another feature' of this invention consists in a special arrangement of the intake and delivery pipes extending to and from the pumpj It has been found that in submarine sound transmitters, Which Work withV movable parts, for example in thecase of sirens, the

r play bet-Ween the' xed and the actuated sound transmission.

parts arising in the course of the Working, for example through iv'ear, forms a source of prejudicial gas discharges 'and causes a considerable reduction'of the effectivenessof the Theeffect ofthis play is obviated according toourinventiombythe employment of a special packing pressure that presses the rotor against the stator atV thepoint Where the sound is produced. This pressure may be effected continuously While the rotor is in motion or only when the siren is caused to emit a sounc.

This measure may be applied to all types of sirens, for example, the drum type, the disc type, etc. Care must, however, betaken that it does not interfere' With any other of the desirable properties of the sirens.

The said packing pressure may be effected by special mechanical Vmeans such as springs and the like, but'thepressure of the operating fluid itself may be advantageously utilized for the said purpose.

In the case of fixed sirens this latter can be effected Without any constructional difficulties being encountered.

In generalthe construction may be such that the pressing of the rotor against the stator at the point Where the sound is pro,- duced is effected either only during sounding, or continuously. A disadvantage of sirens of the former kind is that when the sound control valve is shifted from Silence7 to Soundf the rotor shaft, in consequence of the play between the rotor andthe statorV does not immediately shift over Vto theA one side so as to cause an intimacy of contact be.- tiveen the active portions of the rotor and stator, but instead shiftsover after a series of oscillations have first taken place. Vllhen these oscillations occur the escape of gas from the working vvaterv may take place with the accompanying disadvantages Which have been hereinbeforepointed out. In Vany case .the sound will not be as pure as it Would be if the position of the rotor shaft were continuously the same; In general the form of construction is Vpreferable in which the onesided pressure of the rotor' against Vthe stator is continuous. *A

The intimacy of contact by a preponderance of pressure may also be effected in rcone and ball sirens, asV these types of siren lare to be'regarded as intermediate forms between drum and disc sirens. rlhe one or the other of the methods' explained above will be employed 'according as the particular type under consideration approximates morev nearly the one'forvv the other fundamental typer. v Y Y The invention is explained With reference to' a number of'practical forms shown in the 1 drawings.l y e Y Y Figli isa diagrammatic illustration of siren installation in which the siren is oper-v ated'by a gasless yliquid contained in a closed circuit.

Fig la is a diagrammatic illust-ration'of a siren installation embodying most of theY fundamental yfeatures of the invention. in which thev siren is operated by Water taken in' from' 'theV outside. f

Fig. 2 is a longitudinal section of a .drum siren with external rotor and internal valve.

Figs. 3 and 4.- are transverse' sections of the same on the lines I-I and Il-H respectively ofv Fig.y 2.

Fig. 5 illustrates a drum siren with inter nal rotor Vand external valve in which it is supposed that the pressing of the rotor againsttlie stator is'only effected during sounding.

vFig. 6 shows a transverse section of the same on the line III-'Ill of Fig. 5.

IFig. 7 is a longitudinal section of a'drum siren with internal rotor and external valve, in wl'iich'theone sided pressure is effected continuously.

Figs. 8 and 9 are Ytransverse sections on the lines IV--IVy and V-V respectively of Fig. 7.

Fig.V l0. illustrates a longitudinal section of a disc siren with internal rotor and ex'` ternal valve.

Fig. 1l a longitudinal section of a disc Siren with external rotor and internal valve.

Fig. 12' a longitudinal section of a completely protrudable disc siren with external rotor and internal valve.

Fig. 13 represents a. device for eliminating air from liquid by nie-ans of drizzle plates and a dripping device cooperatingwith a vacuum.

Fig. 14 shows another device for eliminating air from liquid, comprising a stir` ring mechanism and a centrifugal apparatus.

Fig. 15 represents in vertical section an embodiment of our invention in which a diaphragm transmitter is employed.

ln the closed circuit arrangement shown in l, T is a tank attached to the inner side vof the vwall o of aV ship or the like. Through a sleeve T the tank is filled with a lgasless or gas-free liquid L1, for'example, with oil. Said liquid passes through a pipe ./f.` in r-oi'niuunication with the t-ank T near the bottom of the latter, to the pump c by which it is forced through the pipe d and introduced into the sirven e connectedl with tank T i'hroughthe sound'opening g near the top of the tank. 'The pipe d isprovided with a gas cock d, to permit any air contained in the apparatus before it is fille-d to escape when it is being filled.4 Since the liquid contents of the tank T' are entirely free of gas and are caused to flow through the siren in a closed circuit, the yformation of gas bubbles in the siren cannot take place.

ln Fig. la all parts of the plant are arranged below the Vlevel Yof the water in which the ship is floating; and the external' water, which is lused in this plant, enters through intake duct or pipe a connected with the ships `side b. This intake duct supplies the water to pump c. The water is then forced by pump c through the deliveryv or pressure pipe d and introduced into the siren e, all changes of the pressure due Vto expansion by irregularities of the crosssection of the supply pipes being avoided. The intaking capacity of theV intake duct is made greater, of course, than the discharging capacity of the siren; and the intake duct a isdisposed at such a :depth in the water askto maintain a head of water over it sullicient' to Vprevent vsuctional action by the pump c. By these means changes in the pressure of the operating liquidV (which changes would cause dissociation of gas from the liquid, or in other words would cause bubles of gas to appear) are avoided. The siren is shown in the drawing as a fixed drum siren with an internal rotor directly coupled with the driving motor It is` connected with the external` water through the sound opening g. The water pressed through the vsiren flows while the siren is Y sounding, through the sound holes Lr of the rotor R. L,- of the stator S. and Lv of the valve V, and outwards through the sound opening; while, when the siren is silent. it flows through the hole 7i in they bottom I of the siren e, through an auxiliary outlet N yand the holes S., in the stator S, and through holes in the valve V which will then be at the point designated by Sv. Now in order to ensure an intimate contactl between the rotor and the stator the rotor has not only been ground into the staf tor, as this measure alone would not suffice to accomplish the desired effect, but in ad dition the pressure of the operating water is utilized for pressing the rotor against the shaft Wv1 and of which only a rfiagment shown. `By suitablyturning the valve V theV siren may be caused to sound or to be silent. Y

` The sound holes L,v of the rotor are distrib- CII4 sel

uted in the usual manner around its whole i circumference, while in the stator and in the valve the sound holes L q and Lv as will be seen'fromFig. 3 extendonly over a part of the circumference. l 2 to 4, on theside situated opposite to that of the holes LS and Lv, slots Ts and Tv are provided in the stator and the valve respectively which slots,las will be seen in Fig. 2, are arrangedbelow the row 'of sound holes in Vthe rotor and thus allow the water flowing,r

inthe direction of the arrow to pass continuously into the spacel between the rotor and the stator indicatedin the right hand As shown in Figs..

portions of Figs. 2 to 4, the existence of this space being due to play in the bearings of the rotor. The slots T5 and T,l are of such a size that the passage of working water is possible in any position ofthe valve, so that the pressing of the left hand internal surface of the rotor against the left surface of the stator is effected continuously. During the sounding operation this one sided pressure is due to thev fact that on the left side, where the sound is produced, the working water can flow out of the sound holes into the surrounding medium, so that only a slight resistance is offered to its flow, but on the other side there are no sound holes in the stator that permit a free passage of the water so that the water is forced into the space between the stator and rotor at the right hand side and creates a preponderance of pressure there. It is not possible to prevent some of the liquid from continuously flowing through the sound holes situated above the openings TS on the side on which the rotor is pressed away from the stator, but nevertheless the resistance offered to the water by the narrow space between the rotor and stator at the right side will be such that sufficient pressure is obtained to ensure the desired intimacy of contact between the sound producing portions of the rotor and stator. When the siren is silent, the water can pass only through the slots Tv and TS; the rest of the outlets are closed, so that then also a one sided pressing is effected.

If the lateral pressure is to take place only during the sounding of the siren a number of holes Ts instead of one, must be provided in the stator, which correspond in width and spacing with the similar holes Tv in the valve, in order that when the valve is turned to Silence they shall be closed just like the sound holes. l

lnFigs. 5 and 6 a drum siren with internally situated rotor is shown, and it is supposed that the lateral pressure is only to be effected during the sounding. The same reference marks are adopted for such parts as are similar to parts illustrated in Figs. 2

`to 4. The internal rotor E is surrounded first by the stator S, and the stator Sv is in turn surrounded bythe valve V. To obtain a preponderance of pressure on one side in this type of siren is a simple matter, it only being necessary to distribute the sound holes in the stator and in the valve partway around their circumferences. The working water passes through the row of holes Lr into the space between the rotor and the stator on the side situated opposite the sound sector, and effects the tightening on the sounding side by being forced into the space at the opposite side between the rotor and stator. A. peculiarity of this siren consists in the novel design of the stator. This design is in-tended to meet the demand for a protrudable siren with an external valve. If an ordinary Vstandard stator were used, some parts of the externally situated valve would have to be passed through the protrudable stator' casing. This difficulty is overcome in the design shown in the Figs. 5

rotor against the stator is provided for. This form of construction differs from that shown in Figs. 5 and 6 inasmuch as an auX- iliary outlet N is provided in the rotor, which as will be seen from Fig. 9 consists of a row of holes, the width of which, however (see Fig. 8) is greater than that of the holes Lr, so that a sound cannot be produced by the larger holes. Opposite this outlet N, rows of holes Sn and Vn are distributed over a part of the circumference of the stator and of the valve respectively, these holes being so arranged that in certain positions of the valve the working water can pass out. The

upper part of the rotor as well as of theV stator and the valve is formed in the usual manner with the alterations according to the invention, as seen from Fig. 8.

rI he working water thus enters the space between the rotor and the stator and creates a preponderance of pressure there on the side situated opposite the sound sector. If` the valve is set at Sound the upper openings LS and VLV are opened and the lower open-n ings Sn and Vn closed.v The working waterV Moreover, the

n this design, how-'V` ever, a permanent one-sided pressure of the openings Lr and N as before, and thus a lateral tightening pressure is permanently assured in this position of the valve also.

In the case of the disc siren with the internal rotor and external valve illustrated in Fig. 10 the application of the idea ofthe invention is very simple. lt is only necessary to arrange the coupling between the motor shaft and the rotor shaft so that the rotor will be pushed downwards into intimate Contact with the stator by the pressurei wear or spacing `which' takesjpl the two elements. In thedraw ior ensuring this are not shown,"afsfthey will ofy the water a d thus compensate orany ated.

between an external and an intei'na l p r tion of the stator; these portions, being, of. course, shaped las required vfor ay "siren' ofthe,

disc type.

' In the' @aan die. 'sirenswithiextenl.

away from the 4stator by; thevpresfsure' ofithe; water. In the eirainplefshown" thispjis obvi-fV ated by the Yarrangement of a. 'diversion channel Uythatjbranches offfi'roin the siren casing and causes Vtl ie'wo rlnn f waterltopress afcig'ainstaJ parti-of the l`l`lower surfacief offthe' rotor. 'Thislor afsiinilar'forin ofconstru'c' tion cannot beA employed for protru'dable sirens `because n o irregularities lnaylfappear the 'air-*eliminating plant andthe siren. .ln

thisy on the casings of protruldablerens It it be required that discsirensof type shall be protrudable, the iorm'fronf struction shown ini Figf 12 may be adopt-edf The parts, Aemployed'in the productionof' the soundy are indicated 'in the same` 'nian1ier' asin the other The' valve' V'is actuated by vineans of "a hollow shaft H, which' su'rroundsthe driving shaftV ofthe rotor R, and ,the opening through whichY the shaft enters thesiren casing'is VIna`d pressureand water-tight by means: of a stuffing box B. i" The valveis Inovedtonnd fro by a lever Gr and is thus caused to open and close the sound openings. "On its up# per'eXtension the 'shaftW carries' ladisc Alf which rotates on a'` fiired. disc "Ag ballsfli being introducedA between the'. two fdiscs The disc A2 is guided by pD-s`C5`which are` fixed in the-flange 'F :of the sirenfcasing',

ency l*to press: the disc' YA2y upwards?,"This` to inove longitudinally, 'the shaftllViseon! nectedto the 'motor shaft We by means'or an" expansion 'coupling permitting fairial movement and consisting oftwo discs lD',

and Dm'provided with pinsjR1- and R2 which! are guided `in V'correspending holes in th'e "Fi'g. 10 further sho'vvs'a-.siren in the construction of the ,stator'f'is soinewhatf similar to that of Figs 5.*an'd 7 .fIt vwillv be seenthat here Valso the valve V 'is guided' dises Drrand. Dm. Invthis typeeot sirenthe 1. rotor 'is 'of its, meri's d ourse kept continually pressed againstqthefstaton" f Inl lfa device air froin'the working water'-.and consisting of ldringleplates and a .dripping *devicel vis shown which is built'l into'k vtheY hydraulic pressure` supply pipe between the?` force pump l and the siren.' The waterV conveyed bythe punip'c, when entering the air-eliminatingfplantis 'forced through a sieveljyf where, funde'r' certain condition, discharges, f' of gaswilljoccr anda Vva'lvei is 'provided' through which these gases/may escape.` Thc'V weten then "11owsV over an y'oblique ripplingv or drizzling surface/cj in a broad thin*l sheet and in'sd'doing liberates a portion oi2 the air contained in it'f'v Itlthen trickles, yover dripping sieves in., in Vthetank this tank being evacuated Yby `a vac uumV pump Z.' The water tIlomfwhich the `airhasjbeen extracted. then -passesfthrough lthe pipe Zlfto the siren orl` sirens.- "In an "installation of this kind the relimination gofth'e air may be' increased tofany desireddegree by arranging' sliarpy bendsin the supply pipe, byfcausi'ngjthe water to Vfall througha' space andby'increasing the evacuating'power of the vac# uuin;l niay in certain ,cases 4be necessary to"` `counter-balance the losses of 'jpressure arising in the y air-'eliminating "'p'lantff by for d eliminating the means' of a second pu-inpjplaced betweenvv propeller type with one, two,orniore bla'des,v which, ruiming ata speed that can beregu-- lated suitably tothe degree ofthe f airelirnination required; :cause-s" quantities fof gas to Y x be. separatedffroin" the water Lin the" saine inanneras this is caused by'thescrews'ofdj iis af ship' when running in. a yreversed `dire'c...

tion and 'producing the dwell" known ernul# sion-like mixture.of lgas and water.

through the valve '42', lwhile the water and the 'bottoni ef a second pressure receptacle't with double walls,finv which the emulsiongas is thusiiinrnediatelycaused`tobe liberated rorn the water is allowed to escape' gas: @im Contained in'r the IniXture flow. through the pipe rjand'angopening s into.

leo

like mixture is whirled roundby alcentrifir gal device that y separates itjinto its parts. of.v different specific :gravityf The gasless against the inner wall t1 of the tank and flows through outlet openings' u arranged inv this wall in the form of a Venetian blind into the space between the two' walls, and from there through the pipe w to the siren. The lighter parts of the mixture, that is they liberated gas, and the waterfcontaining a large quantity of gas, collect nearV the middle of the tank.V rIhere they ascend andare conveyedthrough the pipel e", which isv con'- nected with the dome Y of the pressure tank t, to another device, for example that shown inV Fig. 13, in which thel air eliminating process is continued, ortliey are simplydischarged without being put to further. use'. rlhe deaerating device shown in. Fig. 14 is not claimed per' se in this application.; it is the invention ofone of the'present" cof-inl ventors, namely, Heinrich Hecht, and is to becovered in the copending application, Se-V ria'l- No. 54883, ifile'd October 8,1915.

rlrhe centrifugal device' employed may be one ofthe known kindv which, with a moderate loss, transforms `the workproduced in the apparatus in the form of kinetic energy into potential energy.

Referring to Fig. 15, M indicates a' housl ing which is filled with liquid Ii2 free from or substantially lacking free gas. Y,The transmitter housing Q is arranged within the housing Mon a partition wall E which' is closed by a diaphragmwhose flange F 'is'y mounted against the flange of housing Q' and connected with the partition wall E'. Within the transmitter housing, any suitable for'm of electro-magnetic transmitter (not structurally shown) is arranged, to. which current is led through thecableX. It is obvious that many other formsof'c'onf struction maybe employed by which the' diaphragm transmitter may readilybe sur# rounded by liquid substantially llf'a'cki'ng free gas, but' the form here shown willservev aslan example.

What we claim and desire to secure Letters Patent is Y 1. In a subaqueous'soundproducing plant,l the combination of a casing, a.- s'ound pro-l ducingv member in said casing, and liquid substantially lacking free gas in the casingY for having sound produced therein by` said Y sound producing member.

, 2. In a subaqueous sound producing plant, the combination of a casing, a sound producing member in said casing, andliquid inv the casing for having sound produced therein by saidsound producing member,.whicli:

bi'natioma Vliquid operated sound producer,

a. source of substantially gas free liquid, and means for supplying said liquid to` said sound producer.

6l In-` a sound producing plant, in coinbination', a liquidoperated sound producer; means" for supplying a liquid thereto, and means for removing gas from the liquid prior to its.' supply tolsa'id, reducer'.

' subaqueous li'q'ui -operated siren,

combined with thefhull of a ship,a pump, an. intake ductY coimecting the water outside the hullto the-.water inlet. of the. pump,and adelivery duct for the passage of water from said pumpto said siren; the intaking capacityy of the intake duct beingV greater than thedischarging capacity of the siren, Vand they intake ducth being, .disposed at -such a depth in.. said water as to maintain a head of waterV over itl suflicient to prevent suctional action'by said pump.

`8. In a subaqueous-liquidooerated drumshap'ed siren, a rotor with sound holes distributed arouiid' its entire circumference, a

stator with sound holes distributedaroundl a partI ofits circumference, a valve with sound lioles, distributed. around a part of its cir,- ciimf'erence, a water passage, meansy forforcing waterI through said passage Vand through the saidf holes inthe stator, the

valve andthe rotor, and'between the parts.

ofthe stator and therotor thath are opposite the said sound holes in the stator, so astov cause a spreadingat this point and therebyanv intimatecontactl betweeny the rotor and` the parts of the'stator `containing the sound,

holes aty the opposite point. Y 9.v In Va subaqueous liquid-operated siren-1 in combination, avrotor and a stator, andmeans for causing and maintaining a pre-y ponderance of pressure in said siren tendingto maintain firm contact of the rotorrwith the stator at the surface adj acentto the point of sound production.

10. In a subaqueous in combination, a rotor Vand a stator, and means for causingv and maintaining a preponderance ofliquid pressure in saidsiren tending. to maintain fir-m contact of the rotor with therstator atlthe surface adjacent'to theip'oint of sound' production.

11. A vibrating diphragin, a liquid4 from which all dissolved gases have been ref liquid-operatedl siren,

moved, and means for retaining said gasfree liquid in Contact With said diaphragm.

12. In combination, a vibrating diaphragm, a liquid from Which allf dissolved gases have been removed, said liquid being adjacent one surface of said diaphragm, and a retaining Vessel for maintaining said liquid in place.

13. In combination, a vibrating diaphragm adapted to send out submarine signals, a liquid from which all dissolved gases have been removed adjacent one surface of the diaphragm, and a retaining vessel for maintaining said liquid in place, they outer surface of said retaining vessel being in contact With the liquid through Which said submarine signals are to be transmitted. di

14. In combination, a vibrating dia,

`phragm adapted to send out submarine -vessel of sound-conducting material forl maintaining said liquid in place, the outer surface of said retaining vessel being in contact With the liquid through which the submarine signals are to be transmitted.

vIn testimony whereof We affix our signatures in presence of tvvo Witnesses.

DI. Phil. HEINRICH HECHT.

FERDINAND SCHENKELBERGER.

Witnesses: v

KARL FRIEDRICH FREUGUT, AMnLEs M. MILLER.

Certificate of Correction.

It is hereby certified that in Letters Patent No. 1,475,385, granted November 27, 1923, upon the application of Heinrich Hecht and Ferdinand Schenkelberger, of Kiel, Germany, for an improvement in Subaqueous Sound-Signal Transmitters, errors appear requiring correction as follows: In the drawings, Sheet 7, strike out the abbreviation andvnumeral Fig. 15 in the heading of the drawings,

line 4, Jfor 7 Sheets read 8 Sheets; a drawing containing Fig. 15 should ap pear as shown below as part of the Letters Patent:

N0" 2.7' 1923' H. HEcl-ir ET "AL,

'sUBAwQUEoUS SOUND SIGNAL .TRANSIMITTE'Rv Filed May 2:8, 1914' y 8 `Sheets-'Sheei. 8

and that the said Letters Patent shouldbe read .with these corrections therein that the same may'conform to the record of the oaseiin the Patent Office,

' Signed and sealed this 26th day of February, A. D., 1924.

[SEAL] p KARL FENNING,

Acting Commissiomr of Patents.

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