The Life of Thomas Telford by Smiles

S >> Samuel Smiles >> The Life of Thomas Telford by Smiles

Pages:
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24

The rest of the work was only a matter of time. The most anxious
moment had passed. In an hour and thirty-five minutes after the
commencement of the hoisting, the chain was raised to its proper
curvature, and fastened to the land portion of it which had been
previously placed over the top of the Anglesea pyramid. Mr. Telford
ascended to the point of fastening, and satisfied himself that a
continuous and safe connection had been formed from the Caernarvon
fastening on the rock to that on Anglesea. The announcement of the
fact was followed by loud and prolonged cheering from the workmen,
echoed by the spectators, and extending along the Straits on both
sides, until it seemed to die away along the shores in the distance.
Three foolhardy workmen, excited by the day's proceedings, had the
temerity to scramble along the upper surface of the chain--which
was only nine inches wide and formed a curvature of 590 feet--from
one side of the Strait to the other!*[2] Far different were the
feelings of the engineer who had planned this magnificent work.
Its failure had been predicted; and, like Brindley's Barton Viaduct,
it had been freely spoken of as a "castle in the air." Telford had,
it is true, most carefully tested every part by repeated experiment,
and so conclusively proved the sufficiency of the iron chains to
bear the immense weight they would have to support, that he was
thoroughly convinced as to the soundness of his principles of
construction, and satisfied that, if rightly manufactured and
properly put together, the chains would hold, and that the piers
would sustain them. Still there was necessarily an element of
uncertainty in the undertaking. It was the largest structure of
the kind that had ever been attempted. There was the contingency
of a flaw in the iron; some possible scamping in the manufacture;
some little point which, in the multiplicity of details to be
attended to, he might have overlooked, or which his subordinates
might have neglected. It was, indeed, impossible but that he
should feel intensely anxious as to the result of the day's
operations. Mr. Telford afterwards stated to a friend, only a few
months before his death, that for some time previous to the opening
of the bridge, his anxiety was so great that he could scarcely
sleep; and that a continuance of that condition must have very soon
completely undermined his health. We are not, therefore, surprised
to learn that when his friends rushed to congratulate him on the
result of the first day's experiment, which decisively proved the
strength and solidity of the bridge, they should have found the
engineer on his knees engaged in prayer. A vast load had been
taken off his mind; the perilous enterprise of the day had been
accomplished without loss of life; and his spontaneous act was
thankfulness and gratitude.

[Image] Menai Bridge

The suspension of the remaining fifteen chains was accomplished
without difficulty. The last was raised and fixed on the 9th of
July, 1825, when the entire line was completed. On fixing the final
bolt, a band of music descended from the top of the suspension pier
on the Anglesea side to a scaffolding erected over the centre of
the curved part of the chains, and played the National Anthem
amidst the cheering of many thousand persons assembled along the
shores of the Strait: while the workmen marched in procession along
the bridge, on which a temporary platform had been laid, and the
St. David steam-packet of Chester passed under the chains towards
the Smithy Rocks and back again, thus re-opening the navigation of
the Strait.

In August the road platform was commenced, and in September the
trussed bearing bars were all suspended. The road was constructed
of timber in a substantial manner, the planking being spiked
together, with layers of patent felt between the planks, and the
carriage way being protected by oak guards placed seven feet and a
half apart. Side railings were added; the toll-houses and
approach-roads were completed by the end of the year; and the
bridge was opened for public traffic on Monday, the 30th of January,
1826, when the London and Holyhead mailcoach passed over it for the
first time, followed by the Commissioners of the Holyhead roads,
the engineer, several stage-coaches, and a multitude of private
persons too numerous to mention.

We may briefly add a few facts as to the quantities of materials
used, and the dimensions of this remarkable structure. The total
weight of iron was 2187 tons, in 33,265 pieces. The total length of
the bridge is 1710 feet, or nearly a third of a mile; the distance
between the points of suspension of the main bridge being 579 feet.
The total sum expended by Government in its erection, including the
embankment and about half a mile of new line of road on the
Caernarvon side, together with the toll-houses, was 120,000L.

Notwithstanding the wonders of the Britannia Bridge subsequently
erected by Robert Stephenson for the passage across the same strait
of the Chester and Holyhead Railway, the Menai Bridge of Telford is
by far the most picturesque object. "Seen as I approached it," says
Mr. Roscoe, "in the clear light of an autumnal sunset, which threw
an autumnal splendour on the wide range of hills beyond, and the
sweep of richly variegated groves and plantations which covered
their base--the bright sun, the rocky picturesque foreground,
villas, spires, and towers here and there enlivening the prospect--
the Menai Bridge appeared more like the work of some great magician
than the mere result of man's skill and industry."

[Image] Conway Suspension Bridge

Shortly after the Menai Bridge was begun, it was determined by the
Commissioners of the Holyhead road that a bridge of similar design
should be built over the estuary of the Conway, immediately
opposite the old castle at that place, and which had formerly been
crossed by an open ferry boat. The first stone was laid on the
3rd of April, 1822, and the works having proceeded satisfactorily,
the bridge and embankment approaching it were completed by the summer
of 1826. But the operations being of the same kind as those
connected with the larger structure above described, though of a
much less difficult character, it is unnecessary to enter into any
details as to the several stages of its construction. In this
bridge the width between the centres of the supporting towers is
327 feet, and the height of the under side of the roadway above
high water of spring tides only 15 feet. The heaviest work was an
embankment as its eastern approach, 2015 feet in length and about
300 feet in width at its highest part.

It will be seen, from the view of the bridge given on the opposite
page, that it is a highly picturesque structure, and combines,
with the estuary which it crosses, and the ancient castle of Conway,
in forming a landscape that is rarely equalled.

Footnotes for Chapter XII.

*[1] In an article in the 'Edinburgh Review,' No. exli., from the
pen of Sir David Brewster, the writer observes:--"Mr. Telford's
principle of suspending and laying down from above the centering of
stone and iron bridges is, we think, a much more fertile one than
even he himself supposed. With modifications, by no means
considerable, and certainly practicable, it appears to us that the
voussoirs or archstones might themselves be laid down from above,
and suspended by an appropriate mechanism till the keystone was
inserted. If we suppose the centering in Mr. Telford's plan to be
of iron, this centering itself becomes an iron bridge, each rib of
which is composed of ten pieces of fifty feet each; and by
increasing the number of suspending chains, these separate pieces
or voussoirs having been previously joined together, either
temporarily or permanently, by cement or by clamps, might be laid
into their place, and kept there by a single chain till the road
was completed. The voussoirs, when united, might be suspended from
a general chain across the archway, and a platform could be added
to facilitate the operations." This is as nearly as possible the
plan afterwards revived by Mr. Brunel, and for the originality of
which, we believe, he has generally the credit, though it clearly
belongs to Telford.

*[2] A correspondent informs us of a still more foolhardy exploit
performed on the occasion. He says, "Having been present, as a boy
from Bangor grammar school, on the 26th of April, when the first
chain was carried across, an incident occurred which made no small
impression on my mind at the time. After the chain had reached its
position, a cobbler of the neighbourhood crawled to the centre of
the curve, and there finished a pair of shoes; when, having
completed his task, he returned in safety to the Caernarvon side!
I need not say that we schoolboys appreciated his feat of
foolhardiness far more than Telford's master work."

CHAPTER XIII.

DOCKS, DRAINAGE, AND BRIDGES.

It will have been observed, from the preceding narrative, how much
had already been accomplished by skill and industry towards opening
up the material resources of the kingdom. The stages of improvement
which we have recorded indeed exhibit a measure of the vital energy
which has from time to time existed in the nation. In the earlier
periods of engineering history, the war of man was with nature.
The sea was held back by embankments. The Thames, instead of being
allowed to overspread the wide marshes on either bank, was confined
within limited bounds, by which the navigable depth of its channel
was increased, at the same time that a wide extent of land was
rendered available for agriculture.

In those early days, the great object was to render the land more
habitable, comfortable, and productive. Marshes were reclaimed, and
wastes subdued. But so long as the country remained comparatively
closed against communication, and intercourse was restricted by the
want of bridges and roads, improvement was extremely slow.
For, while roads are the consequence of civilisation, they are also
among its most influential causes. We have seen even the blind
Metcalf acting as an effective instrument of progress in the
northern counties by the formation of long lines of road. Brindley
and the Duke of Bridgewater carried on the work in the same
districts, and conferred upon the north and north-west of England
the blessings of cheap and effective water communication. Smeaton
followed and carried out similar undertakings in still remoter
places, joining the east and west coasts of Scotland by the Forth
and Clyde Canal, and building bridges in the far north. Rennie made
harbours, built bridges, and hewed out docks for shipping, the
increase in which had kept pace with the growth of our home and
foreign trade. He was followed by Telford, whose long and busy
life, as we have seen, was occupied in building bridges and making
roads in all directions, in districts of the country formerly
inaccessible, and therefore comparatively barbarous. At length the
wildest districts of the Highlands and the most rugged mountain
valleys of North Wales were rendered as easy of access as the
comparatively level counties in the immediate neighbourhood of the
metropolis.

During all this while, the wealth and industry of the country had
been advancing with rapid strides. London had grown in population
and importance. Many improvements had been effected in the river,
But the dock accommodation was still found insufficient; and, as
the recognised head of his profession, Mr. Telford, though now
grown old and fast becoming infirm, was called upon to supply the
requisite plans. He had been engaged upon great works for upwards
of thirty years, previous to which he had led the life of a working
mason. But he had been a steady, temperate man all his life; and
though nearly seventy, when consulted as to the proposed new docks,
his mind was as able to deal with the subject in all its bearings
as it had ever been; and he undertook the work.

In 1824 a new Company was formed to provide a dock nearer to the
heart of the City than any of the existing ones. The site selected
was the space between the Tower and the London Docks, which
included the property of St. Katherine's Hospital. The whole extent
of land available was only twenty-seven acres of a very irregular
figure, so that when the quays and warehouses were laid out, it was
found that only about ten acres remained for the docks; but these,
from the nature of the ground, presented an unusual amount of quay
room. The necessary Act was obtained in 1825; the works were begun
in the following year; and on the 25th of October, 1828, the new
docks were completed and opened for business.

The St. Katherine Docks communicate with the river by means of an
entrance tide-lock, 180 feet long and 45 feet wide, with three
pairs of gates, admitting either one very large or two small
vessels at a time. The lock-entrance and the sills under the two
middle lock-gates were fixed at the depth of ten feet under the
level of low water of ordinary spring tides. The formation of these
dock-entrances was a work of much difficulty, demanding great skill
on the part of the engineer. It was necessary to excavate the
ground to a great depth below low water for the purpose of getting
in the foundations, and the cofferdams were therefore of great
strength, to enable them, when pumped out by the steam-engine, to
resist the lateral pressure of forty feet of water at high tide.
The difficulty was, however, effectually overcome, and the wharf
walls, locks, sills and bridges of the St. Katherine Docks are
generally regarded as a master-piece of harbour construction.
Alluding to the rapidity with which the works were completed,
Mr. Telford says: "Seldom, indeed never within my knowledge, has there
been an instance of an undertaking; of this magnitude, in a very
confined situation, having been perfected in so short a time;....
but, as a practical engineer, responsible for the success of
difficult operations, I must be allowed to protest against such
haste, pregnant as it was, and ever will be, with risks, which, in
more instances than one, severely taxed all my experience and
skill, and dangerously involved the reputation of the directors as
well as of their engineer."

Among the remaining bridges executed by Mr. Telford, towards the
close of his professional career, may be mentioned those of
Tewkesbury and Gloucester. The former town is situated on the
Severn at its confluence with the river Avon, about eleven miles
above Gloucester. The surrounding district was rich and populous;
but being intersected by a large river, without a bridge, the
inhabitants applied to Parliament for powers to provide so
necessary a convenience. The design first proposed by a local
architect was a bridge of three arches; but Mr. Telford, when
called upon to advise the trustees, recommended that, in order to
interrupt the navigation as little as possible, the river should be
spanned by a single arch; and he submitted a design of such a
character, which was approved and subsequently erected. It was
finished and opened in April, 1826.

This is one of the largest as well as most graceful of Mr. Telford's
numerous cast iron bridges. It has a single span of 170 feet, with
a rise of only 17 feet, consisting of six ribs of about three feet
three inches deep, the spandrels being filled in with light
diagonal work. The narrow Gothic arches in the masonry of the
abutments give the bridge a very light and graceful appearance,
at the same time that they afford an enlarged passage for the high
river floods.

The bridge at Gloucester consists of one large stone arch of 150
feet span. It replaced a structure of great antiquity, of eight
arches, which had stood for about 600 years. The roadway over it
was very narrow, and the number of piers in the river and the small
dimensions of the arches offered considerable obstruction to the
navigation. To give the largest amount of waterway, and at the same
time reduce the gradient of the road over the bridge to the
greatest extent, Mr. Telford adopted the following expedient.
He made the general body of the arch an ellipse, 150 feet on the
chord-line and 35 feet rise, while the voussoirs, or external
archstones, being in the form of a segment, have the same chord,
with only 13 feet rise. "This complex form," says Mr. Telford,
"converts each side of the vault of the arch into the shape of the
entrance of a pipe, to suit the contracted passage of a fluid, thus
lessening the flat surface opposed to the current of the river
whenever the tide or upland flood rises above the springing of the
middle of the ellipse, that being at four feet above low water;
whereas the flood of 1770 rose twenty feet above low water of an
ordinary spring-tide, which, when there is no upland flood, rises
only eight or nine feet."*[1] The bridge was finished and opened in
1828.

[Image] Dean Bridge, Edinburgh.

The last structures erected after our engineer's designs were at
Edinburgh and Glasgow: his Dean Bridge at the former place, and his
Jamaica Street Bridge at the latter, being regarded as among his
most successful works. Since his employment as a journeyman mason
at the building of the houses in Princes Street, Edinburgh, the New
Town had spread in all directions. At each visit to it on his way
to or from the Caledonian Canal or the northern harbours, he had
been no less surprised than delighted at the architectural
improvements which he found going forward. A new quarter had risen
up during his lifetime, and had extended northward and westward in
long lines of magnificent buildings of freestone, until in 1829 its
further progress was checked by the deep ravine running along the
back of the New Town, in the bottom of which runs the little Water
of Leith. It was determined to throw a stone bridge across this
stream, and Telford was called upon to supply the design. The point
of crossing the valley was immediately behind Moray Place, which
stands almost upon its verge, the sides being bold, rocky, and
finely wooded. The situation was well adapted for a picturesque
structure, such as Telford was well able to supply. The depth of
the ravine to be spanned involved great height in the piers, the
roadway being 106 feet above the level of the stream. The bridge
was of four arches of 90 feet span each, and its total length 447
feet; the breadth between the parapets for the purposes of the
roadway and footpaths being 39 feet.*[2] It was completed and
opened in December, 1831.

But the most important, as it was the last, of Mr. Telford's stone
bridges was that erected across the Clyde at the Broomielaw,
Glasgow. Little more than fifty years since, the banks of the river
at that place were literally covered with broom--and hence its
name--while the stream was scarcely deep enough to float a
herring-buss. Now, the Broomielaw is a quay frequented by ships of
the largest burden, and bustling with trade and commerce. Skill and
enterprise have deepened the Clyde, dredged away its shoals, built
quays and wharves along its banks, and rendered it one of the
busiest streams in the world,

It has become a great river thoroughfare, worked by steam. On its
waters the first steamboat ever constructed for purposes of traffic
in Europe was launched by Henry Bell in 1812; and the Clyde boats
to this day enjoy the highest prestige.

The deepening of the river at the Broomielaw had led to a gradual
undermining of the foundations of the old bridge, which was
situated close to the principal landing-place. A little above it,
was an ancient overfall weir, which had also contributed to scour
away the foundations of the piers. Besides, the bridge was felt to
be narrow, inconvenient, and ill-adapted for accommodating the
immense traffic passing across the Clyde at that point. It was,
therefore, determined to take down the old structure, and Build a
new one; and Mr. Telford was called upon to supply the design.
The foundation was laid with great ceremony on the 18th of March, 1833,
and the new bridge was completed and opened on the 1st of January,
1836, rather more than a year after the engineer's death. It is a
very fine work, consisting of seven arches, segments of circles,
the central arch being 58 feet 6 inches; the span of the adjoining
arches diminishing to 57 feet 9 inches, 55 feet 6 inches, and 52
feet respectively. It is 560 feet in length, with an open waterway
of 389 feet, and its total width of carriageway and footpath is 60
feet, or wider, at the time it was built, than any river bridge in
the kingdom.

[Image] Glasgow Bridge

Like most previous engineers of eminence--like Perry, Brindley,
Smeaton, and Rennie--Mr. Telford was in the course of his life
extensively employed in the drainage of the Fen districts. He had
been jointly concerned with Mr. Rennie in carrying out the
important works of the Eau Brink Cut, and at Mr. Rennie's death he
succeeded to much of his practice as consulting engineer.

It was principally in designing and carrying out the drainage of
the North Level that Mr. Telford distinguished himself in Fen
drainage. The North Level includes all that part of the Great
Bedford Level situated between Morton's Leam and the river Welland,
comprising about 48,000 acres of land. The river Nene, which brings
down from the interior the rainfall of almost the entire county of
Northampton, flows through nearly the centre of the district.
In some places the stream is confined by embankments, in others it
flows along artificial outs, until it enters the great estuary of
the Wash, about five miles below Wisbeach. This town is situated on
another river which flows through the Level, called the Old Nene.
Below the point of junction of these rivers with the Wash, and
still more to seaward, was South Holland Sluice, through which the
waters of the South Holland Drain entered the estuary. At that
point a great mass of silt had accumulated, which tended to choke
up the mouths of the rivers further inland, rendering their
navigation difficult and precarious, and seriously interrupting the
drainage of the whole lowland district traversed by both the Old
and New Nene. Indeed the sands were accumulating at such a rate,
that the outfall of the Wisbeach River threatened to become
completely destroyed.

Such being the state of things, it was determined to take the
opinion of some eminent engineer, and Mr. Rennie was employed to
survey the district and recommend a measure for the remedy of these
great evils. He performed this service in his usually careful and
masterly manner; but as the method which he proposed, complete
though it was, would have seriously interfered with the trade of
Wisbeach, by leaving it out of the line of navigation and drainage
which he proposed to open up, the corporation of that town
determined to employ another engineer; and Mr Telford was selected
to examine and report upon the whole subject, keeping in view the
improvement of the river immediately adjacent to the town of
Wisbeach.

Mr. Telford confirmed Mr. Rennie's views to a large extent, more
especially with reference to the construction of an entirely new
outfall, by making an artificial channel from Kindersleys Cut to
Crab-Hole Eye anchorage, by which a level lower by nearly twelve
feet would be secured for the outfall waters; but he preferred
leaving the river open to the tide as high as Wisbeach, rather than
place a lock with draw-doors at Lutton Leam Sluice, as had been
proposed by Mr. Rennie. He also suggested that the acute angle at
the Horseshoe be cut off and the river deepened up to the bridge at
Wisbeach, making a new cut along the bank on the south side of the
town, which should join the river again immediately above it,
thereby converting the intermediate space, by draw-doors and the
usual contrivances, into a floating dock. Though this plan was
approved by the parties interested in the drainage, to Telford's
great mortification it was opposed by the corporation of Wisbeach,
and like so many other excellent schemes for the improvement of the
Fen districts, it eventually fell to the ground.

The cutting of a new outfall for the river Nene, however, could not
much longer be delayed without great danger to the reclaimed lands
of the North Level, which, but for some relief of the kind, must
shortly have become submerged and reduced to their original waste
condition. The subject was revived in 1822, and Mr. Telford was
again called upon, in conjunction with Sir John Rennie, whose
father had died in the preceding year, to submit a plan of a new
Nene Outfall; but it was not until the year 1827 that the necessary
Act was obtained, and then only with great difficulty and cost, in
consequence of the opposition of the town of Wisbeach. The works
consisted principally of a deep cut or canal, about six miles in
length, penetrating far through the sand banks into the deep waters
of the Wash. They were begun in 1828, and brought to completion in
1830, with the most satisfactory results. A greatly improved
outfall was secured by thus carrying. the mouths of the rivers out
to sea, and the drainage of the important agricultural districts
through which the Nene flows was greatly benefited; while at the
same time nearly 6000 acres of valuable corn-growing land were
added to the county of Lincoln.

Pages:
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24