the life of thomas telford-第52节
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was concerned; were much more satisfactory than in the case of the
Caledonian Canal。 While in the one case he had much obloquy to
suffer for the services he had given; in the other he was honoured
and feted as a public benefactor; the King conferring upon him the
Swedish order of knighthood; and presenting him with his portrait
set in diamonds。
Among the various canals throughout England which Mr。 Telford was
employed to construct or improve; down to the commencement of the
railway era; were the Gloucester and Berkeley Canal; in 1818; the
Grand Trunk Canal; in 1822; the Harecastle Tunnel; which he
constructed anew; in 1824…7; the Birmingham Canal; in 1824; and the
Macclesfield; and Birmingham and Liverpool Junction Canals; in 1825。
The Gloucester and Berkeley Canal Company had been unable to
finish their works; begun some thirty years before; but with the
assistance of a loan of 160;000L。 from the Exchequer Bill Loan
Commissioners; they were enabled to proceed with the completion of
their undertaking。 A capacious canal was cut from Gloucester to
Sharpness Point; about eight miles down the Severn; which had the
effect of greatly improving the convenience of the port of
Gloucester; and by means of this navigation; ships of large burden
can now avoid the circuitous and difficult passage of the higher
part of the river; very much to the advantage of the trade of the
place。
The formation of a new tunnel through Harecastle Hill; for the
better accommodation of the boats passing along the Grand Trunk
Canal; was a formidable work。 The original tunnel; it will be
remembered;*'3' was laid out by Brindley; about fifty years
before; and occupied eleven years in construction。 But the
engineering appliances of those early days were very limited; the
pumping powers of the steam…engine had not been fairly developed;
and workmen were as yet only half…educated in the expert use of
tools。 The tunnel; no doubt; answered the purpose for which it was
originally intended; but it was very soon found too limited for the
traffic passing along the navigation。 It was little larger than a
sewer; and admitted the passage of only one narrow boat; seven feet
wide; at a time; involving very heavy labour on the part of the men
who worked it through。 This was performed by what was called
legging。 The Leggers lay upon the deck of the vessel; or upon a
board slightly projecting from either side of it; and; by thrusting
their feet against the slimy roof or sides of the tunnel…walking
horizontally as it were they contrived to push it through。
But it was no better than horsework; and after 〃legging〃 Harecastle
Tunnel; which is more than a mile and a half long; the men were
usually completely exhausted; and as wet from perspiration as if
they had been dragged through the canal itself。 The process
occupied about two hours; and by the time the passage of the tunnel
was made; there was usually a collection of boats at the other end
waiting their turn to pass。 Thus much contention and confusion
took place amongst the boatmena very rough class of labourers
and many furious battles were fought by the claimants for the first
turn 〃through。〃 Regulations were found of no avail to settle these
disputes; still less to accommodate the large traffic which
continued to keep flowing along the line of the Grand Trunk;
and steadily increased with the advancing trade and manufactures of
the country。 Loud complaints were made by the public; but they were
disregarded for many years; and it was not until the proprietors
were threatened with rival canals and railroads that they
determined onwhat they could no longer avoid if they desired to
retain the carrying trade of the district the enlargement of the
Harecastle Tunnel。
Mr。 Telford was requested to advise the Company what course was
most proper to be adopted in the matter; and after examining the
place; he recommended that an entirely new tunnel should be
constructed; nearly parallel with the old one; but of much larger
dimensions。 The work was begun in 1824; and completed in 1827;
in less than three years。 There were at that time throughout the
country plenty of skilled labourers and contractors; many of them
trained by their experience upon Telford's own works; where as
Brindley had in a great measure to make his workmen out of the
rawest material。 Telford also had the advantage of greatly improved
machinery and an abundant supply of moneythe Grand Trunk Canal
Company having become prosperous and rich; paying large dividends。
It is therefore meet; while eulogising the despatch with which he
was enabled to carry out the work; to point out that the much
greater period occupied in the earlier undertaking is not to be set
down to the disparagement of Brindley; who had difficulties to
encounter which the later engineer knew nothing of。
The length of the new tunnel is 2926 yards; it is 16 feet high and
14 feet broad; 4 feet 9 inches of the breadth being occupied by the
towing…pathfor 〃legging〃 was now dispensed with; and horses
hauled along the boats instead of their being thrust through by
men。 The tunnel is in so perfectly straight a line that its whole
length can be seen through at one view; and though it was
constructed by means of fifteen different pitshafts sunk to the
same line along the length of the tunnel; the workmanship is so
perfect that the joinings of the various lengths of brickwork are
scarcely discernible。 The convenience afforded by the new tunnel
was very great; and Telford mentions that; on surveying it in 1829;
he asked a boatman coming; out of it how he liked it? 〃I only
wish;〃 he replied; 〃that it reached all the way to Manchester!〃
'Image' Cross Section of Harecastle Tunnel。
At the time that Mr。 Telford was engaged upon the tunnel at
Harecastle; he was employed to improve and widen the Birmingham
Canal; another of Brindley's works。 Though the accommodation
provided by it had been sufficient for the traffic when originally
constructed; the expansion of the trade of Birmingham and the
neighbourhood; accelerated by the formation of the canal itself;
had been such as completely to outgrow its limited convenience and
capacity; and its enlargement and improvement now became absolutely
necessary。 Brindley's Canal; for the sake of cheapness of
constructionmoney being much scarcer and more difficult to be
raised in the early days of canalswas also winding and crooked;
and it was considered desirable to shorten and straighten it by
cutting off the bends at different places。 At the point at which
the canal entered Birmingham; it had become 〃little better than a
crooked ditch; with scarcely the appearance of a towing…path; the
horses frequently sliding and staggering in the water; the
hauling…lines sweeping the gravel into the canal; and the
entanglement at the meeting of boats being incessant; whilst at the
locks at each end of the short summit at Smethwick crowds of
boatmen were always quarrelling; or offering premiums for a
preference of passage; and the mine…owners; injured by the delay;
were loud in their just complaints。〃*'4'
Mr。 Telford proposed an effective measure of improvement; which
was taken in hand without loss of time; and carried out; greatly
to the advantage of the trade of the district。 The numerous bends
in the canal were cut off; the water…way was greatly widened; the
summit at Smethwick was cut down to the level on either side; and a
straight canal; forty feet wide; without a lock; was thus formed
as far as Bilston and Wolverhampton; while the length of the main
line between Birmingham and Autherley; along the whole extent of
the 〃Black country;〃 was reduced from twenty…two to fourteen miles。
At the same time the obsolete curvatures in Brindley's old canal
were converted into separate branches or basins; for the
accommodation of the numerous mines and manufactories on either
side of the main line。 In consequence of the alterations which had
been made in the canal; it was found necessary to construct
numerous large bridges。 One of thesea cast iron bridge;
at Galton; of 150 feet spanhas been much admired for its elegance;
lightness; and economy of material。 Several others of cast iron
were constructed at different points; and at one place the canal
itself is carried along on an aqueduct of the same material as at
Pont…Cysylltau。 The whole of these extensive improvements were
carried out in the short space of two years; and the result was
highly satisfactory; 〃proving;〃 as Mr。 Telford himself observes;
〃that where business is extensive; liberal expenditure of this kind
is true economy。〃
'Image' Galton Bridge; Birmingham Canal。
In 1825 Mr。 Telford was called upon to lay out a canal to connect
the Grand Trunk; at the north end of Harecastle Tunnel; with the
rapidly improving towns of Congleton and Macclesfield。 The line
was twenty…nine miles in len