the life of thomas telford-第50节

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Caledonian　Canal；　that　of　two　vessels　despatched　from　Newcastle　on

the　same　dayone　bound　for　Liverpool　by　the　north　of　Scotland；　and

the　other　for　Bombay　by　the　English　Channel　and　the　Cape　of　Good　Hope

the　latter　reached　its　destination　first！　　Another　case　may　be

mentioned；　that　of　an　Inverness　vessel；　which　sailed　for　Liverpool

on　a　Christmas　Day；　reached　Stromness　Harbour；　in　Orkney；　on　the

1st　of　January；　and　lay　there　windbound；　with　a　fleet　of　other

traders；　until　the　middle　of　April　following！　　In　fact；　the　Pentland

Frith；　which　is　the　throat　connecting　the　Atlantic　and　German　Oceans；

through　which　the　former　rolls　its；　long　majestic　waves　with

tremendous　force；　was　long　the　dread　of　mariners；　and　it　was

considered　an　object　of　national　importance　to　mitigate　the　dangers

of　the　passage　towards　the　western　Seas。



As　the　lochs　occupying　the　chief　part　of　the　bottom　of　the　Great

Glen　were　of　sufficient　depth　to　be　navigable　by　large　vessels；

it　was　thought　that　if　they　could　be　connected　by　a　ship　canal；

so　as　to　render　the　line　of　navigation　continuous；　it　would　be　used

by　shipping　to　a　large　extent；　and　prove　of　great　public　service。

Five　hundred　miles　of　dangerous　navigation　by　the　Orkneys　and

Cape　Wrath　would　thereby　be　saved；　while　ships　of　war；　were　this

track　open　to　them；　might　reach　the　north　of　Ireland　in　two　days

from　Fort　George　near　Inverness。



When　the　scheme　of　the　proposed　canal　was　revived　in　1801；

Mr。　Telford　was　requested　to　make　a　survey　and　send　in　his　report　on

the　subject。　He　immediately　wrote　to　his　friend　James　Watt；　saying；

〃I　have　so　long　accustomed　myself　to　look　with　a　degree　of　reverence

at　your　work；　that　I　am　particularly　anxious　to　learn　what　occurred

to　you　in　this　business　while　the　whole　was　fresh　in　your　mind。　　The

object　appears　to　me　so　great　and　so　desirable；　that　I　am　convinced

you　will　feel　a　pleasure　in　bringing　it　again　under　investigation；

and　I　am　very　desirous　that　the　thing　should　be　fully　and　fairly

explained；　so　that　the　public　may　be　made　aware　of　its　extensive

utility。　　If　I　can　accomplish　this；　I　shall　have　done　my　duty；　and

if　the　project　is　not　executed　now；　some　future　period　will　see　it

done；　and　I　shall　have　the　satisfaction　of　having　followed　you　and

promoted　its　success。〃　　We　may　here　state　that　Telford's　survey

agreed　with　Watt's　in　the　most　important　particulars；　and　that　he

largely　cited　Watt's　descriptions　of　the　proposed　scheme　in　his　own

report。



Mr。　Telford's　first　inspection　of　the　district　was　made　in　1801；

and　his　report　was　sent　in　to　the　Treasury　in　the　course　of　the

following　year。　　Lord　Bexley；　then　Secretary　to　the　Treasury；　took

a　warm　personal　interest　in　the　project；　and　lost　no　opportunity　of

actively　promoting　it。　　A　board　of　commissioners　was　eventually

appointed　to　carry　out　the　formation　of　the　canal。　　Mr。　Telford；

on　being　appointed　principal　engineer　of　the　undertaking；　was

requested　at　once　to　proceed　to　Scotland　and　prepare　the　necessary

working　survey。　　He　was　accompanied　on　the　occasion　by　Mr。　Jessop

as　consulting　engineer。　　Twenty　thousand　pounds　were　granted　under

the　provisions　of　the　43　Geo。　III。　（chap。　cii。）；　and　the　works

were　commenced；　in　the　beginning　of　1804；　by　the　formation　of　a

dock　or　basin　adjoining　the　intended　tide…lock　at　Corpach；　near

Bannavie。



＇Image＇　Map　of　Caledonian　Canal



The　basin　at　Corpach　formed　the　southernmost　point　of　the　intended

canal。　　It　is　situated　at　the　head　of　Loch　Eil；　amidst　some　of　the

grandest　scenery　of　the　Highlands。　　Across　the　Loch　is　the　little

town　of　Fort　William；　one　of　the　forts　established　at　the　end　of

the　seventeenth　century　to　keep　the　wild　Highlanders　in　subjection。

Above　it　rise　hills　over　hills；　of　all　forms　and　sizes；　and　of　all

hues；　from　grass…green　below　to　heather…brown　and　purple　above；

capped　with　heights　of　weather…beaten　grey；　while　towering　over　all

stands　the　rugged　mass　of　Ben　Nevisa　mountain　almost　unsurpassed

for　picturesque　grandeur。　　Along　the　western　foot　of　the　range；

which　extends　for　some　six　or　eight　miles；　lies　a　long　extent　of

brown　bog；　on　the　verge　of　which；　by　the　river　Lochy；　stand　the

ruins　of　Inverlochy　Castle。



The　works　at　Corpach　involved　great　labour；　and　extended　over　a

long　series　of　years。　　The　difference　between　the　level　of　Loch　Eil

and　Loch　Lochy　is　ninety　feet；　while　the　distance　between　them　was

less　than　eight　miles。　　It　was　therefore　necessary　to　climb　up　the

side　of　the　hill　by　a　flight　of　eight　gigantic　locks；　clustered

together；　and　which　Telford　named　Neptune's　Staircase。　　The　ground

passed　over　was　in　some　places　very　difficult；　requiring　large

masses　of　embankment；　the　slips　of　which　in　the　course　of　the　work

frequently　occasioned　serious　embarrassment。　　The　basin　on　Loch　Eil；

on　the　other　hand；　was　constructed　amidst　rock；　and　considerable

difficulty　was　experienced　in　getting　in　the　necessary　coffer…dam

for　the　construction　of　the　opening　into　the　sea…lock；　the

entrance…sill　of　which　was　laid　upon　the　rock　itself；　so　that　there

was　a　depth　of　21　feet　of　water　upon　it　at　high　water　of　neap　tides。



At　the　same　time　that　the　works　at　Corpach　were　begun；　the　dock　or

basin　at　the　north…eastern　extremity　of　the　canal；　situated　at

Clachnaharry；　on　the　shore　of　Loch　Beauly；　was　also　laid　out；　and

the　excavations　and　embankments　were　carried　on　with　considerable

activity。　　This　dock　was　constructed　about　967　yards　long；　and

upwards　of　162　yards　in　breadth；　giving　an　area　of　about　32　acres；

forming；　in　fact；　a　harbour　for　the　vessels　using　the　canal。　The

dimensions　of　the　artificial　waterway　were　of　unusual　size；　as　the

intention　was　to　adapt　it　throughout　for　the　passage　of　a　32…gun

frigate　of　that　day；　fully　equipped　and　laden　with　stores。　　The

canal；　as　originally　resolved　upon；　was　designed　to　be　110　feet

wide　at　the　surface；　and　50　feet　at　the　bottom；　with　a　depth　in　the

middle　of　20　feet；　though　these　dimensions　were　somewhat　modified

in　the　execution　of　the　work。　　The　locks　were　of　corresponding

large　dimensions；　each　being　from　170　to　180　feet　long；　40　broad；

and　20　deep。



＇Image＇　Lock；　Caledonian　Canal



Between　these　two　extremities　of　the　canalCorpach　on　the

south…west　and　Clachnaharry　on　the　north…eastextends　the　chain　of

fresh…water　lochs：　Loch　Lochy　on　the　south；　next　Loch　Oich；　then

Loch　Ness；　and　lastly；　furthest　north；　the　small　Loch　of　Dochfour。

The　whole　length　of　the　navigation　is　60　miles　40　chains；　of　which

the　navigable　lochs　constitute　about　40　miles；　leaving　only　about

20　miles　of　canal　to　be　constructed；　but　of　unusually　large

dimensions　and　through　a　very　difficult　country。



The　summit　loch　of　the　whole　is　Loch　Oich；　the　surface　of　which　is

exactly　a　hundred　feet　above　high　water…mark；　both　at　Inverness　and

Fort　William；　and　to　this　sheet　of　water　the　navigation　climbs　up

by　a　series　of　locks　from　both　the　eastern　and　western　seas。

The　whole　number　of　these　is　twenty…eight：　the　entrance…lock　at

Clachnaharry；　constructed　on　piles；　at　the　end　of　huge　embankments；

forced　out　into　deep　water；　at　Loch　Beady；　another　at　the　entrance

to　the　capacious　artificial　harbour　above　mentioned；　at　Muirtown；

four　connected　locks　at　the　southern　end　of　this　basin；

a　regulating　lock　a　little　to　the　north　of　Loch　Dochfour；

five　contiguous　locks　at　Fort　Augustus；　at　the　south　end　of　Loch　Ness；

another；　called　the　Kytra　Lock；　about　midway　between　Fort　Angustus

and　Loch　Oich；　a　regulating　lock　at　the　north…east　end　of　Loch　Oich；

two　contiguous　locks　between　Lochs　Oich　and　Lochy；　a　regulating

lock　at　the　south…west　end　of　Loch　Lochy；　next；　the　grand　series　of

locks；　eight　in　number；　called　〃Neptune's　Staircase；〃　at　Bannavie；

within　a　mile　and　a　quarter　of　the　sea；　two　locks；　descending　to

Corpach　basin；　and　lastly；　the　great　entrance　or　sea…lock　at　Corpach。



The　northern　entrance…lock　from　the　sea　at　Loch　Beauly　is　at

Clachnaharry；　near　Inverness。　　The　works　here　were　not　accomplished

without　much　difficulty　as　well　as　labour；　partly　from　the　very

gradual　declivity　of　the　shore；　and　partly　from　the　necessity　of

placing　the　sea…lock　on　absolute　mud；　which　afforded　no　foundation

other　than　what　was　created　by　compression　and　pile…driving。

The　mud　was　forced　down　by　throwing　upon　it　an　immense　load　of　earth

and　stones；　which　was　left　during　twelve　months　to　settle；　after

which　a　shaft　was　sunk　to　a　solid　foundation；　and　the　masonry　of

the　sea…lock　was　then　founded　and　built　therein。



In　the　'Sixteenth　Report　of　the　Commissioners　of　the　Caledonian

Canal；'　the　following　reference　is　made　to　this　important　work；

which　was　finished　in　1812：　〃The　depth　of　the　mud　on　which　it　may

be　said　to　be　artificially　seated　is　not　less　than　60　feet；　so　that

it　cannot　be　deemed　superfluous；　at　the　end　of　seven　years；　to

state　that　no　subsidence　is　discoverable；　and　we　presume　that　the

entire　lock；　as　well　as　every　pa