the life of thomas telford-第59章
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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 length; ten miles on one level from
Harecastle to beyond Congleton; then; ascending 114 feet by eleven
locks; it proceeded for five miles on a level past Macclesfield;
and onward to join the Peak Forest Canal at Marple。 The navigation
was thus conducted upon two levels; each of considerable length;
and it so happened that the trade of each was in a measure
distinct; and required separate accommodation。 The traffic of the
whole of the Congleton district had ready access to the Grand Trunk
system; without the labour; expense; and delay involved by passing
the boats through locks; while the coals brought to Macclesfield to
supply the mills there were carried throughout upon the upper
level; also without lockage。 The engineer's arrangement proved
highly judicious; and furnishes an illustration of the tact and
judgment which he usually displayed in laying out his works for
practical uses。 Mr Telford largely employed cast iron in the
construction of this canal; using it in the locks and gates; as
well as in an extensive aqueduct which it was necessary to
construct over a deep ravine; after the plan pursued by him at;
Pont…Cysylltau and other places。
The last canal constructed by。 Mr。 Telford was the Birmingham and
Liverpool Junction; extending from the Birmingham Canal; near
Wolverhampton; in nearly a direct line; by Market Drayton;
Nantwich; and through the city of Chester; by the Ellesmere Canal;
to Ellesmere Port on the Mersey。 The proprietors of canals were
becoming alarmed at the numerous railways projected through the
districts heretofore served by their water…ways; and among other
projects one was set on foot; as early as 1825; for constructing a
line of railway from London to Liverpool。 Mr。 Telford was
consulted as to the best means of protecting existing investments;
and his advice was to render the canal system as complete as it
could be made; for he entertained the conviction; which has been
justified by experience; that such navigations possessed peculiar
advantages for the conveyance of heavy goods; and that; if the
interruptions presented by locks could be done away with; or
materially reduced; a large portion of the trade of the country
must continue to be carried by the water roads。 The new line
recommended by him was approved and adopted; and the works were
commenced in 1826。 A second complete route was thus opened up
between Birmingham and Liverpool; and Manchester; by which the
distance was shortened twelve miles; and the delay occasioned by
320 feet of upward and downward lockage was done away with。
Telford was justly proud of his canals; which were the finest works
of their kind that had yet been executed in England。 Capacious;
convenient; and substantial; they embodied his most ingenious
contrivances; and his highest engineering skill。 Hence we find him
writing to a friend at Langholm; that; so soon as he could find
〃sufficient leisure from his various avocations in his own
unrivalled and beloved island;〃 it was his intention to visit
France and Italy; for the purpose of ascertaining what foreigners
had been able to accomplish; compared with ourselves; in the
construction of canals; bridges; and harbours。 〃I have no doubt;〃
said he; 〃as to their inferiority。 During the war just brought to
a close; England has not only been able to guard her own head and
to carry on a gigantic struggle; but at the same time to construct
canals; roads; harbours; bridgesmagnificent works of peacethe
like of which are probably not to be found in the world。 Are not
these things worthy of a nation's pride?〃
Footnotes for Chapter X。
*'1' Mr。 Matthew Davidson; above referred to; was an excellent
officer; but a strange cynical humourist in his way。 He was a
Lowlander; and had lived for some time in England; at the Pont
Cysylltau works; where he had acquired a taste for Englis