andBruneltolaunchtheGreatEasternsteamshipfromhercradles。Ithasalsobeenusedtocutbarsofiron,todrawthepilesdriveninformingcofferdams,andtowrenchuptreesbytheroots,allofwhichfeatsitaccomplisheswithcomparativeease。
TheprincipaldifficultyexperiencedinconstructingthehydraulicpressbeforethetimeofBramaharosefromthetremendouspressureexercisedbythepump,whichforcedthewaterthroughbetweenthesolidpistonandthesideofthecylinderinwhichitworkedinsuchquantitiesastorenderthepressuselessforpracticalpurposes。
Bramahhimselfwasatfirstcompletelybaffledbythisdifficulty。Itwillbeobservedthattheproblemwastosecureajointsufficientlyfreetoletthepistonslideupthroughit,andatthesametimesowater-tightastowithstandtheinternalforceofthepump。ThesetwoconditionsseemedsoconflictingthatBramahwasalmostathiswit’send,andforatimedespairedofbeingabletobringthemachinetoastateofpracticalefficiency。Nonebutthosewhohaveoccupiedthemselvesinthelaboriousandoftenprofitlesstaskofhelpingtheworldtonewandusefulmachinescanhaveanyideaofthetantalizinganxietywhicharisesfromtheapparentlypettystumbling-blockswhichforawhileimpedetherealizationofagreatideainmechanicalinvention。Suchwasthecasewiththewater-tightarrangementinthehydraulicpress。Inhisearlyexperiments,Bramahtriedtheexpedientoftheordinarystuffing-boxforthepurposeofsecuringtherequiredwatertightness’Thatis,acoilofhemponleatherwasherswasplacedinarecess,soastofittightlyroundthemovingramorpiston,anditwasfurtherheldinitsplacebymeansofacompressingcollarforcedharddownbystrongscrews。Thedefectofthisarrangementwas,that,evensupposingthepackingcouldbemadesufficientlytighttoresistthepassageofthewaterurgedbythetremendouspressurefrombeneath,suchwasthegripwhichthecompressedmaterialtookoftheramofthepress,thatitcouldnotbegottoreturndownafterthewaterpressurehadbeenremoved。
Inthisdilemma,Bramah’sever-readyworkman,HenryMaudslay,cametohisrescue。Thehappyideaoccurredtohimofemployingthepressureofthewateritselftogivetherequisitewater-tightnesstothecollar。Itwasaflashofcommon-sensegenius——beautifulthroughitsverysimplicity。TheresultwasMaudslay’sself-tighteningcollar,theactionofwhichafewwordsofdescriptionwillrendereasilyintelligible。Acollarofsoundleather,theconvexsideupwardsandtheconcavedownwards,wasfittedintotherecessturnedoutintheneckofthepress-cylinder,attheplaceformerlyusedasastuffing-box。Immediatelyonthehighpressurewaterbeingturnedon,itforceditswayintotheleathernconcavityand’flappedout’
thebentedgesofthecollar;and,insodoing,causedtheleathertoapplyitselftothesurfaceoftherisingramwithadegreeofclosenessandtightnesssoastosealupthejointthecloserexactlyinproportiontothepressureofthewaterinitstendencytoescape。
Ontheotherhand,themomentthepressurewasletoffandtheramdesiredtoreturn,thecollarcollapsedandtheramslidgentlydown,perfectlyfreeandyetperfectlywater-tight。Thus,theformertendencyofthewatertoescapebythesideofthepistonwasbythismostsimpleandelegantself-adjustingcontrivancemadeinstrumentaltotheperfectlyefficientactionofthemachine;andfromthemomentofitsinventionthehydraulicpresstookitsplaceasoneofthegrandestagentsforexercisingpowerinaconcentratedandtranquilform。
Bramahcontinuedhisusefullaboursasaninventorformanyyears。
Hisstudyoftheprinciplesofhydraulics,inthecourseofhisinventionofthepress,enabledhimtointroducemanyvaluableimprovementsinpumping-machinery。Byvaryingtheformofthepistonandcylinderhewasenabledtoobtainarotarymotion,*
[footnote……
Dr。ThomasYoung,inhisarticleonBramahintheEncyclopaediaBritannica,describesthe”rotativeprinciple”asconsistinginmakingthepartwhichactsimmediatelyonthewaterintheformofaslider,”sweepingroundacylindricalcavity,andkeptinitsplacebymeansofaneccentricgroove;acontrivancewhichwasprobablyBramah’sowninvention,butwhichhadbeenbeforedescribed,inaformnearlysimilar,byRamelli,Canalleri,Amontons,PrinceRupert,andDr。Hooke。
whichheadvantageouslyappliedtomanypurposes。Thusheadopteditinthewellknownfire-engine,theuseofwhichhasalmostbecomeuniversal。Anotherpopularmachineofhisisthebeer-pump,patentedin1797,bywhichthepublicanisenabledtoraisefromthecasksinthecellarbeneath,thevariousliquorssoldbyhimoverthecounter。
Healsotookoutseveralpatentsfortheimprovementofthesteam-engine,inwhich,however,Wattleftlittleroomforotherinventors;andhenceBramahseemstohaveentertainedagrudgeagainstWatt,whichbrokeoutfiercelyintheevidencegivenbyhiminthecaseofBoultonandWattversusHornblowerandMaberly,triedinDecember1796。Onthatoccasionhistemperseemstohavegotthebetterofhisjudgment,andhewascutshortbythejudgeintheattemptwhichhethenmadetosubmitthecontentsofthepamphletsubsequentlypublishedbyhimintheformofalettertothejudgebeforewhomthecasewastried。*
[footnote……
ALettertotheRightHon。SirJamesEyre,LordChiefJusticeoftheCommonPleas,onthesubjectofthecauseBoultonandWattv。HornblowerandMaberly,forInfringementonMr。Watt’sPatentforanImprovementoftheSteamEngine。ByJosephBramah,Engineer。
London,1797。
InthatpamphlethearguedthatWatt’sspecificationhadnodefinitemeaning;thatitwasinconsistentandabsurd,andcouldnotpossiblybeunderstood;thattheproposaltoworksteam-enginesontheprincipleofcondensationwasentirelyfallacious;thatWatt’smethodofpackingthepistonwas”monstrousstupidity;”thattheenginesofNewcomensinceentirelysupersededwereinfinitelysuperior,inallrespects,tothoseofWatt;——conclusionswhich,weneedscarcelysay,havebeenrefutedbytheexperienceofnearlyacentury。
OntheexpiryofBoultonandWatt’spatent,Bramahintroducedseveralvaluableimprovementsinthedetailsofthecondensingengine,whichhadbythattimebecomeanestablishedpower,——themostimportantofwhichwashis”four-waycock,”whichhesoarrangedastorevolvecontinuouslyinsteadofalternately,thusinsuringgreaterprecisionwithconsiderablylesswearofparts。Inthesamepatentbywhichhesecuredthisinventionin1801,healsoproposedsundryimprovementsintheboilers,aswellasmodificationsinvariouspartsoftheengine,withtheobjectofeffectinggreatersimplicityanddirectnessofaction。
Inhispatentof1802,wefindBramahmakinganothergreatstrideinmechanicalinvention,inhistools”forproducingstraight,smooth,andparallelsurfacesonwoodandothermaterialsrequiringtruth,inamannermuchmoreexpeditiousandperfectthancanbeperformedbytheuseofaxes,saws,planes,andothercuttinginstrumentsusedbyhandintheordinaryway。”Thespecificationdescribestheobjectoftheinventiontobethesavingofmanuallabour,thereductioninthecostofproduction,andthesuperiorcharacteroftheworkexecuted。
Thetoolswerefixedonframesdrivenbymachinery,somemovinginarotarydirectionroundanuprightshaft,somewiththeshafthorizontallikeanordinarywood-turninglathe,whileinothersthetoolswerefixedonframesslidinginstationarygrooves。A
wood-planingmachine*
[footnote……
SirSamuelBenthamandMarcIsambardBrunelsubsequentlydistinguishedthemselvesbytheinventionofwood-workingmachinery,fullaccountsofwhichwillbefoundintheMemoirsoftheformerbyLadyBentham,andintheLifeofthelatterbyMr。Beamish。
wasconstructedontheprincipleofthisinventionatWoolwichArsenal,whereitstillcontinuesinefficientuse。Theaxisoftheprincipalshaftwassupportedonapistoninavesselofoil,whichconsiderablydiminishedthefriction,anditwassocontrivedastobeaccuratelyregulatedbymeansofasmallforcing-pump。Althoughthemachinerydescribedinthepatentwasfirstappliedtoworkingonwood,itwasequallyapplicabletoworkingonmetals;andinhisownshopsatPimlicoBramahemployedamachinewithrevolvingcutterstoplanemetallicsurfacesforhispatentlocksandotherarticles。Healsointroducedamethodofturningsphericalsurfaces,eitherconvexorconcave,byatoolmoveableonanaxisperpendiculartothatofthelathe;andofcuttingoutconcentricshellsbyfixinginasimilarmanneracurvedtoolofnearlythesameformasthatemployedbycommonturnersformakingbowls。”Infact,”saysMr。Mallet,”Bramahnotonlyanticipated,butcarriedoutuponatolerablylargescaleinhisownworks——fortheconstructionofthepatenthydraulicpress,thewater-closet,andhislocks——asurprisinglylargeproportionofourmoderntools。”*
[footnote……”RecordoftheInternationalExhibition,1862。”PracticalMechanic’sJournal,293。
Hisremarkablepredilectioninfavouroftheuseofhydraulicarrangementsisdisplayedinhisspecificationofthesurface-planingmachinery,whichincludesamethodofrunningpivotsentirelyonafluid,andraisinganddepressingthematpleasurebymeansofasmallforcing-pumpandstop-cock,——thoughwearenotawarethatanypracticalusehaseverbeenmadeofthispartoftheinvention。
Bramah’sinventivegeniusdisplayeditselfalikeinsmallthingsasingreat——inatapwherewithtodrawaglassofbeer,andinahydraulicmachinecapableoftearingupatreebytheroots。Hispowersofcontrivanceseemedinexhaustible,andwereexercisedonthemostvarioussubjects。Whenanydifficultyoccurredwhichmechanicalingenuitywascalculatedtoremove,recoursewasusuallyhadtoBramah,andhewasrarelyfoundatalossforacontrivancetoovercomeit。Thus,whenappliedtobytheBankofEnglandin1806,toconstructamachineformoreaccuratelyandexpeditiouslyprintingthenumbersanddatelinesonBanknotes,heatonceproceededtoinventtherequisitemodel,whichhecompletedinthecourseofamonth。Hesubsequentlybroughtittogreatperfectionthefiguresinnumericalsuccessionbeingchangedbytheactionofthemachineitself,——anditstillcontinuesinregularuse。ItsemploymentintheBankofEnglandalonesavedthelabourofahundredclerks;butitschiefvalueconsistedinitsgreateraccuracy,theperfectlegibilityofthefiguresprintedbyit,andthegreatlyimprovedcheckwhichitafforded。
Wenextfindhimoccupyinghimselfwithinventionsconnectedwiththemanufactureofpensandpaper。Hislittlepen-makingmachineforreadilymakingquillpenslongcontinuedinuse,untildrivenoutbytheinventionofthesteelpen;buthispatentformakingpaperbymachinery,thoughingenious,likeeverythinghedid,doesnotseemtohavebeenadopted,theinventionsofFourdrinierandDonkininthisdirectionhavingshortlysupersededallothers。Amonghisotherminorinventionsmaybementionedhisimprovedmethodofconstructingandsledgingcarriage-wheels,andhisimprovedmethodoflayingwater-pipes。Inhisspecificationofthelast-mentionedinvention,heincludedtheapplicationofwater-powertothedrivingofmachineryofeverydescription,andforhoistingandloweringgoodsindocksandwarehouses,——sincecarriedoutinpractice,thoughinadifferentmanner,bySirWilliamArmstrong。*
[footnote……
Inthis,asinothermethodsofemployingpower,themodernshadbeenanticipatedbytheancients;andthoughhydraulicmachineryisacomparativelyrecentinventioninEngland,ithadlongbeeninuseabroad。ThuswefindinDr。Bright’sTravelsinLowerHungaryafulldescriptionofthepowerfulhydraulicmachineryinventedbyM。Holl,ChiefEngineeroftheImperialMines,whichhadbeeninusesincetheyear1749,inpumpingwaterfromadepthof1800feet,fromthesilverandgoldminesofSchemnitzandKremnitz。Aheadofwaterwascollectedbyformingareservoiralongthemountainside,fromwhichitwasconductedthroughwater-tightcast-ironpipeserectedperpendicularlyinthemine-shaft。Aboutforty-fivefathomsdown,thewaterdescendingthroughthepipewasforcedbytheweightofthecolumnaboveitintothebottomofaperpendicularcylinder,inwhichitraisedawater-tightpiston。Whenforceduptoagivenpointaself-actingstop-cockshutoffthepressureofthedescendingcolumn,whileaself-actingvalveenabledthewatercontainedinthecylindertobedischarged,onwhichthepistonagaindescended,andtheprocesswasrepeatedlikethesuccessivestrokesofasteam-engine。
Pump-rodswereattachedtothishydraulicapparatus,whichwerecarriedtothebottomoftheshaft,andeachworkedapumpatdifferentlevels,raisingthewaterstagebystagetothelevelofthemainadit。Thepumpsofthesethreeseveralstageseachraised1790cubicfeetofwaterfromadepthof600feetinthehour。Theregularworkingofthemachinerywasaidedbytheemploymentofabalance-beamconnectedbyachainwiththeheadofthelargepistonandpump-rods;andthewholeofthesepowerfulmachinesbymeansofthreeofwhichasmuchas789,840gallonsofwaterwerepumpedoutoftheminesevery24hours——weresetinoperationandregulatedmerelybytheturningofastopcock。Itwillbeobservedthatthearrangementthusbrieflydescribedwasequallyapplicabletotheworkingofmachineryofallkinds,cranes,&c。,aswellaspumps;anditwillbenotedthat,notwithstandingtheingenuityofBramah,Armstrong,andothereminentEnglishmechanics,theAustrianengineerHollwasthusdecidedlybeforehandwiththeminthepracticalapplicationoftheprinciplesofhydrostatics。