WeareinformedthatitwaswhileRichardReynoldshadchargeoftheCoalbrookdaleworksthatafurtherimportantimprovementwaseffectedinthemanufactureofironbypit-coal。Uptothistimetheconversionofcrudeorcastironintomalleableorbarironhadbeeneffectedentirelybymeansofcharcoal。Theprocesswascarriedoninafirecalledafinery，somewhatlikethatofasmith’sforge；theironbeingexposedtotheblastofpowerfulbellows，andinconstantcontactwiththefuel。Inthefirstprocessoffusingtheironstone，coalhadbeenusedforsometimewithincreasingsuccess；butthequestionarose，whethercoalmightnotalsobeusedwitheffectinthesecondorrefiningstage。Twooftheforemen，namedCranege，suggestedtoMr。Reynoldsthatthismightbeperformedinwhatiscalledareverberatoryfurnace，*
[footnote……
Reverberatory，socalledbecausetheflameorcurrentofheatedgasesfromthefueliscausedtobereverberatedorreflecteddownuponthesubstanceunderoperationbeforepassingintothechimney。ItiscuriousthatRovenson，inhisTreatiseofMetallicaof1613，describesareverberatoryfurnaceinwhichironwastobesmeltedbypit-coal，thoughitdoesnotappearthathesucceededinperfectinghisinvention。Dr。Percy，inhisexcellentworkonMetallurgy，thusdescribesareverberatoryfurnace：——”Itconsistsessentiallyofthreeparts——afireplaceatoneend，astackorchimneyattheother，andabedbetweenbothonwhichthematterisheated。Thefireplaceisseparatedfromthebedbyalowpartitionwallcalledthefire-bridge，andbotharecoveredbyanarchedroofwhichrisesfromtheendwallofthefireplaceandgraduallydipstowardthefurthestendofthebedconnectedwiththestack。Ononeorbothsidesofthebed，orattheendnearthestack，maybeopeningsthroughwhichtheorespreadoverthesurfaceofthebedmaybestirredaboutandexposedtotheactionoftheair。Thematterisheatedinsuchafurnacebyflame，andiskeptfromcontactwiththesolidfuel。TheflameinitscoursefromthefireplacetothestackisreflecteddownwardsorREVERBERATEDonthematterbeneath，whencethenameREVERBERATORYfurnace。”
inwhichtheironshouldnotmixwiththecoal，butbeheatedsolelybytheflame。Mr。Reynoldsgreatlydoubtedthefeasibilityoftheoperation，butheauthorizedtheCranege，tomakeanexperimentoftheirprocess，theresultofwhichwillbefounddescribedinthefollowingextractofaletterfromMr。ReynoldstoMr。ThomasGoldneyofBristol，dated”Coalbrookdale，25thApril，1766”：……”IcomenowtowhatIthinkamatterofverygreatconsequence。
ItissometimesinceThos。Cranege，whoworksatBridgenorthForge，andhisbrotherGeorge，oftheDale，spoketomeaboutanotiontheyhadconceivedofmakingbarironwithoutwoodcharcoal。Itoldthem，consistentwiththenotionIhadadoptedincommonwithallothersI
hadconversedwith，thatIthoughtitimpossible，becausethevegetablesaltsinthecharcoalbeinganalkaliactedasanabsorbenttothesulphuroftheiron，whichoccasionsthered-shortqualityoftheiron，andpitcoalaboundingwithsulphurwouldincreaseit。Thisspeciousanswer，whichwouldprobablyhaveappearedconclusivetomost，andwhichindeedwaswhatIreallythought，wasnotsotothem。
Theyrepliedthatfromtheobservationstheyhadmade，andrepeatedconversationstogether，theywerebothfirmlyofopinionthatthealterationfromthequalityofpigironintothatofbarironwaseffectedmerelybyheat，andifIwouldgivethemleave，theywouldmakeatrialsomeday。Iconsented，but，Iconfess，withoutanygreatexpectationoftheirsuccess；andsothematterrestedsomeweeks，whenithappeningthatsomerepairshadtobedoneatBridgenorth，ThomascameuptotheDale，and，withhisbrother，madeatrialinThos。Tilly’sair-furnacewithsuchsuccessasIthoughtwouldjustifytheerectionofasmallair-furnaceattheForgeforthemoreperfectlyascertainingthemeritoftheinvention。Thiswasaccordinglydone，andatrialofithasbeenmadethisweek，andthesuccesshassurpassedthemostsanguineexpectations。TheironputintothefurnacewasoldBushes，whichthouknowestarealwaysmadeofhardiron，andtheirondrawnoutisthetoughestIeversaw。A
bar11/4inchsquare，whenbroke，appearstohaveverylittlecoldshortinit。Ilookuponitasoneofthemostimportantdiscoveriesevermade，andtakethelibertyofrecommendingtheeandearnestlyrequestingthouwouldsttakeoutapatentforitimmediately……Thespecificationoftheinventionwillbecomprisedinafewwords，asitwillonlysetforththatareverberatoryfurnacebeingbuiltofaproperconstruction，thepigorcastironisputintoit，andwithouttheadditionofanythingelsethancommonrawpitcoal，isconvertedintogoodmalleableiron，and，beingtakenred-hotfromthereverberatoryfurnacetotheforgehammer，isdrawnoutintobarsofvariousshapesandsizes，accordingtothewilloftheworkmen。”
Mr。Reynolds’sadvicewasimplicitlyfollowed。ApatentwassecuredinthenameofthebrothersCranege，datedthe17thJune，1766；andtheidenticalwordsintheaboveletterwereadoptedinthespecificationasdescriptiveoftheprocess。Bythismethodofpuddling，asitistermed，themanufacturerwasthenceforwardenabledtoproduceironinincreasedquantityatalargereductioninprice；
andthoughtheinventionoftheCranegeswasgreatlyimproveduponbyOnions，andsubsequentlybyCort，therecanbenodoubtastotheoriginalityandtheimportanceoftheirinvention。Mr。TylorstatesthathewasinformedbythesonofRichardReynoldsthatthewroughtironmadeatCoalbrookdalebytheCranegeprocess”wasverygood，quitetough，andbrokewithalong，bright，fibrousfracture：thatmadebyCortafterwardswasquitedifferent。”*
[footnote……
Mr。TYLORonMetalWork——ReportsontheParisExhibitionof1855。
PartII。182。WeareinformedbyMr。ReynoldsofCoed-du，agrandsonofRichardReynolds，that”onfurthertrialsmanydifficultiesarose。
Thebottomsofthefurnacesweredestroyedbytheheat，andthequalityoftheironvaried。Still，byaletterdatedMay，1767，itappearstherehadbeensoldofironmadeinthenewwaytothevalueof247L。14s。6d。”
ThoughMr。Reynolds’sgenerositytotheCranegesisapparent；inthecoursewhichheadoptedinsecuringforthemapatentfortheinventionintheirownnames，itdoesnotappeartohaveprovedofmuchadvantagetothem；andtheyfailedtoriseabovetherankwhichtheyoccupiedwhentheirvaluablediscoverywaspatented。This，however，wasnofaultofRichardReynolds，butwasmainlyattributabletothecircumstanceofotherinventionsinagreatmeasuresupersedingtheirprocess，anddeprivingthemofthebenefitsoftheiringenuity。
AmongtheimportantimprovementsintroducedbyMr。ReynoldswhilemanagingtheCoalbrookdaleWorks，wastheadoptionbyhimforthefirsttimeofironinsteadofwoodenrailsinthetram-roadsalongwhichcoalandironwereconveyedfromonepartoftheworkstoanother，aswellastotheloading-placesalongtheriverSevern。Heobservedthatthewoodenrailssoonbecamedecayed，besidesbeingliabletobebrokenbytheheavyloadspassingoverthem，occasioningmuchlossoftime，interruptiontobusiness，andheavyexpensesinrepairs。Itoccurredtohimthattheseinconvenienceswouldbeobviatedbytheuseofrailsofcast-iron；and，havingtriedanexperimentwiththem，itansweredsowell，thatin1767thewholeofthewoodenrailsweretakenupandreplacedbyrailsofiron。ThuswastheeraofironrailroadsfairlyinitiatedatCoalbrookdale，andtheexampleofMr。ReynoldswasshortlyafterfollowedonallthetramroadsthroughouttheCountry。
ItisalsoworthyofnotethatthefirstironbridgeevererectedwascastandmadeattheCoalbrookdaleWorks——itsprojectionaswellasitserectionbeingmainlyduetotheskillandenterpriseofAbrahamDarbythethird。Whenbutayoungman，heshowedindicationsofthatsagacityandenergyinbusinesswhichseemedtobehereditaryinhisfamily。Oneofthefirstthingshedidonarrivingatman’sestatewastosetonfootaschemeforthrowingabridgeacrosstheSevernatCoalbrookdale，atapointwherethebanksweresteepandslippery，toaccommodatethelargepopulationwhichhadsprungupalongbothbanksoftheriver。Therewerenowthrivingiron，brick，andpotteryworksestablishedintheparishesofMadeleyandBroseley；andtheoldferryontheSevernwasfoundaltogetherinadequateforreadycommunicationbetweenonebankandtheother。Thewantofabridgehadlongbeenfelt，andaplanofonehadbeenpreparedduringthelifetimeofAbrahamDarbythesecond；buttheprojectwassuspendedathisdeath。Whenhissoncameofage，heresolvedtotakeuphisfather’sdroppedscheme，andprosecuteittocompletion，whichhedid。YoungMr。DarbybecamelordofthemanorofMadeleyin1776，andwastheownerofone-halfoftheferryinrightofhislordship。HewassofortunateastofindtheowneroftheotherorBroseleyhalfoftheferryequallyanxiouswithhimselftoconnectthetwobanksoftheriverbymeansofabridge。ThenecessarypowerswereaccordinglyobtainedfromParliament，andabridgewasauthorizedtobebuilt”ofcast-iron，stone，brick，ortimber。”Acompanywasformedforthepurposeofcarryingouttheproject，andthesharesweretakenbytheadjoiningowners，AbrahamDarbybeingtheprincipalsubscriber。*
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AmongtheothersubscribersweretheRev。Mr。Harris，Mr。Jennings，andMr。JohnWilkinson，anactivepromoterofthescheme，whogavethecompanythebenefitofhisskillandexperiencewhenitwasdeterminedtoconstructthebridgeofiron。ForanaccountofJohnWilkinsonseeLivesoftheEngineers，vol。ii。337，356。Inthedescriptionofthefirstironbridgegiveninthatworkwehave，itappears，attributedrathermorecredittoMr。Wilkinsonthanheisentitledto。Mr。Darbywasthemostactivepromoterofthescheme，andhadtheprincipalshareinthedesign。Wilkinsonneverthelesswasamanofgreatenergyandoriginality。Besidesbeingthebuilderofthefirstironship，hewasthefirsttoinvent，forJamesWatt，amachinethatwouldboreatolerablytruecylinder。HeafterwardsestablishedironworksinFrance，andArthurYoungsays，that”untilthatwell-knownEnglishmanufacturerarrived，theFrenchknewnothingoftheartofcastingcannonsolidandthenboringthem”TravelsinFrance，4to。ed。London，1792，p。90。YetEnglandhadborrowedherfirstcannon-makerfromFranceinthepersonofPeterBaude，asdescribedinchap。iii。Wilkinsonisalsosaidtohaveinventedakindofhot-blast，inrespectofwhichvariouswitnessesgaveevidenceonthetrialofNeilson’spatentin1839；buttheinventiondoesnotappeartohavebeenperfectedbyhim。
Theconstructionofabridgeofironwasanentirelynewidea。AnattempthadindeedbeenmadeatLyons，inFrance，toconstructsuchabridgemorethantwentyyearsbefore；butithadentirelyfailed，andabridgeoftimberwaserectedinstead。ItisnotknownwhethertheCoalbrookdalemastershadheardofthatattempt；but，eveniftheyhad，itcouldhavebeenofnopracticalusetothem。
Mr。Pritchard，anarchitectofShrewsbury，wasfirstemployedtoprepareadesignoftheintendedstructure，whichisstillpreserved。
AlthoughMr。Pritchardproposedtointroducecast-ironinthearchofthebridge，whichwastobeof120feetspan，itwasonlyasasortofkey，occupyingbutafewfeetatthecrownofthearch。Thissparinguseofcastironindicatesthetimidityofthearchitectindealingwiththenewmaterial——hisplanexhibitingadesiretoeffectacompromisebetweenthetriedandtheuntriedinbridge-construction。Buttheuseofirontosolimitedanextent，andinsuchapartofthestructure，wasofmorethanquestionableutility；andifMr。Pritchard’splanhadbeenadopted，theproblemoftheironbridgewouldstillhaveremainedunsolved。
Theplan，however，afterhavingbeendulyconsidered，waseventuallysetaside，andanother，withtheentirearchofcast-iron，waspreparedunderthesuperintendenceofAbrahamDarby，byMr。ThomasGregory，hisforemanofpattem-makers。Thisplanwasadopted，andarrangementswereforthwithmadeforcarryingitintoeffect。Theabutmentsofthebridgewerebuiltin1777-8，duringwhichthecastingsweremadeatthefoundry，andtheironworkwassuccessfullyerectedinthecourseofthreemonths。Thebridgewasopenedfortrafficin1779，andprovedamostserviceablestructure。In1788theSocietyofArtsrecognisedMr。Darby’smeritasitsdesigneranderectorbypresentinghimwiththeirgoldmedal；andthemodelofthebridgeisstilltobeseeninthecollectionoftheSociety。Mr。
RobertStephensonhassaidofthestructure：”Ifweconsiderthatthemanipulationofcast-ironwasthencompletelyinitsinfancy，abridgeofsuchdimensionswasdoubtlessaboldaswellasanoriginalundertaking，andtheefficiencyofthedetailsisworthyoftheboldnessoftheconception。”*
[footnote……
EncyclopaediaBritannica，8thed。Art。”IronBridges。”