按键盘上方向键 ← 或 → 可快速上下翻页，按键盘上的 Enter 键可回到本书目录页，按键盘上方向键 ↑ 可回到本页顶部！
————未阅读完？加入书签已便下次继续阅读！
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