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the life of thomas telford-第56章

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canal; and he also prepared a scheme: but nothing was done。 The

project was; however; revived in 1801 during the war with Napoleon;

when various inland ship canalssuch as those from London to

Portsmouth; and from Bristol to the English Channelwere under

consideration with the view of enabling British shipping to pass

from one part of the kingdom to another without being exposed to

the attacks of French privateers。  But there was another reason for

urging the formation of the canal through the Great Glen of Scotland;

which was regarded as of considerable importance before the

introduction of steam enabled vessels to set the winds and tides at

comparative defiance。  It was this: vessels sailing from the

eastern ports to America had to beat up the Pentland Frith; often

against adverse winds and stormy seas; which rendered the navigation

both tedious and dangerous。  Thus it was cited by Sir Edward Parry;

in his evidence before Parliament in favour of completing the

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 t

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