ing　challenge　from　the　North。　The　echo　ran　〃Low　Bridge！〃　in　the　poor　decaying　locks　of　the　Potomac　Company　where；　according　to　the　committee　once　appointed　to　examine　that　enterprise；　flood…tides　〃gave　the　only　navigation　that　was　enjoyed。〃　Were　their　efforts　to　keep　the　Chesapeake　metropolis　in　the　lead　to　be　set　at　naught？
  There　could　be　but　one　answer　to　the　challenge；　and　that　was　to　rival　canal　with　canal。　These　more　southerly　States；　confronted　by　the　towering　ranges　of　the　Alleghanies　to　the　westward；　showed　a　courage　which　was　superb；　although；　as　time　proved　in　the　case　of　Maryland；　they　might　well　have　taken　more　counsel　of　their　fears。　Pennsylvania　acted　swiftly。　Though　its　western　waterway　the　roaring　Juniata；　which　entered　the　Susquehanna　near　Harrisburghad　a　drop　from　head　to　mouth　greater　than　that　of　the　entire　New　York　canal；　and；　though　the　mountains　of　the　Altoona　region　loomed　straight　up　nearly　three　thousand　feet；　Pennsylvania　overcame　the　lowlands　by　main　strength　and　the　mountain　peaks　by　strategy　and　was　sending　canal　boats　from　Philadelphia　to　Pittsburgh　within　nine　years　of　the　completion　of　the　Erie　Canal。
  The　eastern　division　of　the　Pennsylvania　Canal；　known　as　the　Union　Canal；　from　Reading　on　the　Schuylkill　to　Middletown　on　the　Susquehanna；　was　completed　in　1827。　The　Juniata　section　was　then　driven　on　up　to　Hollidaysburg。　Beyond　the　mountain　barrier；　the　Conemaugh；　the　Kiskiminitas；　and　the　Allegheny　were　followed　to　Pittsburgh。　But　the　greatest　feat　in　the　whole　enterprise　was　the　conquest　of　the　mountain　section；　from　Hollidaysburg　to　Johnstown。　This　was　accomplished　by　the　building　of　five　inclined　planes　on　each　slope；　each　plane　averaging　about　2300　feet　in　length　and　200　feet　in　height。　Up　or　down　these　slopes　and　along　the　intermediate　level　sections　cars　and　giant　cradles　（built　to　be　lowered　into　locks　where　they　could　take　an　entire　canal　boat　as　a　load）　were　to　be　hauled　or　lowered　by　horsepower；　and　later；　by　steam。　After　the　plans　had　been　drawn　up　by　Sylvester　Welch　and　Moncure　Robinson；　the　Pennsylvania　Legislature　authorized　the　work　in　1831；　and　traffic　over　this　aerial　route　was　begun　in　March；　1834。　In　autumn　of　that　year；　the　stanch　boat　Hit　or　Miss；　from　the　Lackawanna　country；　owned　by　Jesse　Crisman　and　captained　by　Major　Williams；　made　the　journey　across　the　whole　length　of　the　canal。　It　rested　for　a　night　on　the　Alleghany　summit　〃like　Noah's　Ark　on　Ararat；〃　wrote　Sherman　Day；　〃descended　the　next　morning　into　the　Valley　of　the　Mississippi；　and　sailed　for　St。　Louis。〃
  Well　did　Robert　Stephenson；　the　famous　English　engineer；　say　that；　in　boldness　of　design　and　difficulty　of　execution；　this　Pennsylvania　scheme　of　mastering　the　Alleghanies　could　be　compared　with　no　modern　triumph　short　of　the　feats　performed　at　the　Simplon　Pass　and　Mont　Cenis。　Before　long　this　line　of　communication　became　a　very　popular　thoroughfare；　even　Charles　Dickens　〃heartily　enjoyed〃　itin　retrospectand　left　interesting　impressions　of　his　journey　over　it：
  〃Even　the　running　up；　bare…necked；　at　five　o'clock　in　the　morning　from　the　tainted　cabin　to　the　dirty　deck；　scooping　up　the　icy　water；　plunging　one's　head　into　it；　and　drawing　it　out；　all　fresh　and　glowing　with　the　cold；　was　a　good　thing。　The　fast；　brisk　walk　upon　the　towing…path；　between　that　time　and　breakfast；　when　every　vein　and　artery　seemed　to　tingle　with　health；　the　exquisite　beauty　of　the　opening　day；　when　light　came　gleaming　off　from　everything；　the　lazy　motion　of　the　boat；　when　one　lay　idly　on　the　deck；　looking　through；　rather　than　at；　the　deep　blue　sky；　the　gliding　on；　at　night；　so　noiselessly；　past　frowning　hills；　sullen　with　dark　trees；　and　sometimes　angry　in　one　red　burning　spot　high　up；　where　unseen　men　lay　crouching　round　a　fire；　the　shining　out　of　the　bright　stars；　undisturbed　by　noise　of　wheels　or　steam；　or　any　other　sound　than　the　liquid　rippling　of　the　water　as　the　boat　went　on；　all　these　were　pure　delights。〃*
  *　〃American　Notes〃　（Gadshill　Edition）；　pp。　180…181。
  Dickens　also　thus　graphically　depicts　the　unique　experience　of　being　carried　over　the　mountain　peaks　on　the　aerial　railway：
  〃There　are　ten　inclined　planes；　five　ascending　and　five　descending；　the　carriages　are　dragged　up　the　former；　and　let　slowly　down　the　latter；　by　means　of　stationary　engines；　the　comparatively　level　spaces　between　being　traversed；　sometimes　by　horse；　and　sometimes　by　engine　power；　as　the　case　demands。　Occasionally　the　rails　are　laid　upon　the　extreme　verge　of　a　giddy　precipice；　and　looking　from　the　carriage　window；　the　traveler　gazes　sheer　down；　without　a　stone　or　scrap　of　fence　between；　into　the　mountain　depths　below。　The　journey　is　very　carefully　made；　however；　only　two　carriages　traveling　together；　and　while　proper　precautions　are　taken；　is　not　to　be　dreaded　for　its　dangers。
  〃It　was　very　pretty　traveling　thus；　at　a　rapid　pace　along　the　heights　of　the　mountain　in　a　keen　wind；　to　look　down　into　a　valley　full　of　light　and　softness；　catching　glimpses；　through　the　tree…tops；　of　scattered　cabins；　children　running　to　the　doors；　dogs　bursting　out　to　bark；　whom　we　could　see　without　hearing；　terrified　pigs　scampering　homewards；　families　sitting　out　in　their　rude　gardens；　cows　gazing　upward　with　a　stupid　indifference；　men　in　their　shirt…sleeves　looking　on　at　their　unfinished　houses；　planning　out　tomorrow's　work；　and　we　riding　onward；　high　abode　them；　like　a　whirl…wind。　It　was　amusing；　too；　when　we　had　dined；　and　rattled　down　a　steep　pass；　having　no　other　motive　power　than　the　weight　of　the　carriages　themselves；　to　see　the　engine　released；　long　after　us；　come　buzzing　down　alone；　like　a　great　insect；　its　back　of　green　and　gold　so　shining　in　the　sun；　that　if　it　had　spread　a　pair　of　wings　and　soared　away；　no　one　would　have　had　occasion；　as　I　fancied；　for　the　least　surprise。　But　it　stopped　short　of　us　in　a　very　business…like　manner　when　we　reached　the　canal；　and；　before　we　left　the　wharf；　went　panting　up　this　hill　again；　with　the　passengers　who　had　waited　our　arrival　for　the　means　of　traversing　the　road　by　which　we　had　come。〃*
  *　Op。　cit。
  This　Pennsylvania　route　was　likewise　famous　because　it　included　the　first　tunnel　in　America；　but　with　the　advance　of　years；　tunnel；　planes；　and　canal　were　supplanted　by　what　was　to　become　in　time　the　Pennsylvania　Railroad；　the　pride　of　the　State　and　one　of　the　great　highways　of　the　nation。
  In　the　year　before　Pennsylvania　investigated　her　western　water　route；　a　joint　bill　was　introduced　into　the　legislatures　of　the　Potomac　Valley　States；　proposing　a　Potomac　Canal　Company　which　should　construct　a　Chesapeake　and　Ohio　canal　at　the　expense　of　Maryland；　Virginia；　and　the　District　of　Columbia。　The　plan　was　of　vital　moment　to　Alexandria　and　Georgetown　on　the　Potomac；　but　unless　a　lateral　canal　could　be　built　to　Baltimore；　that　city　which　paid　a　third　of　Maryland's　taxeswould　be　called　on　to　supply　a　great　sum　to　benefit　only　her　chief　rivals。　The　bitter　struggle　which　now　developed　is　one　of　the　most　significant　in　commercial　history　because　of　its　sequel。
  The　conditions　underlying　this　rivalry　must　not　be　lost　sight　of。　Baltimore　had　done　more　than　any　other　Eastern　city　to　ally　herself　with　the　West　and　to　obtain　its　trade。　She　had　instinctively　responded　to　every　move　made　by　her　rivals　in　the　great　game。　If　Pennsylvania　promoted　a　Lancaster　Turnpike；　Baltimore　threw　out　her　superb　Baltimore…Reisterstown　boulevard；　though　her　northern　road　to　Philadelphia　remained　the　slough　that　Brissot　and　Baily　had　found　it。　If　New　York　projected　an　Erie　Canal；　Baltimore　successfully　championed　the　building　of　a　Cumberland　Road　by　a　governmental　godmother。　So　thoroughly　and　quickly；　indeed；　did　she　link　her　system　of　stone　roads　to　that　great　artery；　that　even　today　many　well…informed　writers　seem　to　be　under　the　impression　that　the　Cumberland　Road　ran　from　the　Ohio　to　Washington　and　Baltimore。　Now；　with　canals　building　to　the　north　of　her　and　canals　to　the　south　of　her；　what　of　her　prestige　and　future？
  For　the　moment　Baltimore　compromised　by　agreeing　to　a　Chesapeake　and　Ohio　canal　which；　by　a　lateral　branch；　should　still　lead　to　her　market　square。　Her　scheme　embraced　a　vision　of　conquest　regal　in　its　sweep；　beyond　that　of　any　rival；　and　comprehending　two　ideas　worthy　of　the　most　farseeing　strategist　and　the　most　astute　politician。　It　called　not　only　for　the　building　of　a　transmontane　canal　to　the　Ohio　but　also　for　a　connecting　canal　from　the　Ohio　to　the　Great　Lakes。　Not　only　would　the　trade　of　the　Northwest　be　secured　by　this　meansfor　this　southerly　route　would　not　be　affected　by　winter　frosts　as　would　those　of　Pennsylvania　and　New　Yorkbut　the　good　godmother　at　Washington　would　be　almost　certain　to　champion　it　and　help　to　build　it　since　the　proposed　route　was　so　thoroughly　interstate　in　character。　With　the　backing　of　Maryland；　Virginia；　Western　Pennsylvania；　Ohio；　and　probably　several　States　bordering　the　Inland　Lakes；　government　aid　in　the　undertaking　seemed　feasible　and　proper。
  Theoretically　the　daring　scheme　captured　the　admiration　of　all　who　were　to　be　benefited　by　it。　At　a　great　banquet　at　Washington；　late　in　1823；　the　project　was　launched。　Adams；　Clay；　and　Calhoun　took　the　opportunity　to　ally　themselves　with　it　by　robus