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。