The heaviest and most important part of the undertaking was in
carrying the canal through the rugged country between the rivers
Dee and Ceriog, in the vale of Llangollen.  From Nantwich to
Whitchurch the distance is 16 miles, and the rise 132 feet,
involving nineteen locks; and from thence to Ellesmere, Chirk,
Pont-Cysylltau, and the river Dee, 1 3/4 mile above Llangollen, the
distance is 38 1/4 miles, and the rise 13 feet, involving only two
locks.  The latter part of the undertaking presented the greatest
difficulties; as, in order to avoid the expense of constructing
numerous locks, which would also involve serious delay and heavy
expense in working the navigation, it became necessary to contrive
means for carrying the canal on the same level from one side of the
respective valleys of the Dee and the Ceriog to the other; and
hence the magnificent aqueducts of Chirk and Pont-Cysylltau,
characterised by Phillips as "among the boldest efforts of human
invention in modem times."*[2]  The Chirk Aqueduct carries the canal
across the valley of the Ceriog, between Chirk Castle and the
village of that name.  At this point the valley is above 700 feet
wide; the banks are steep, with a flat alluvial meadow between
them, through which the river flows. The country is finely
wooded.  Chirk Castle stands on an eminence on its western side,
with the Welsh mountains and Glen Ceriog as a background; the whole
composing a landscape of great beauty, in the centre of which
Telford's aqueduct forms a highly picturesque object.

[Image] Chirk Aqueduct

The aqueduct consists of ten arches of 40 feet span each.
The level of the water in the canal is 65 feet above the meadow,
and 70 feet above the level of the river Ceriog.  The proportions
of this work far exceeded everything of the kind that had up to
that time been attempted in England.  It was a very costly structure;
but Telford, like Brindley, thought it better to incur a considerable
capital outlay in maintaining the uniform level of the canal, than
to raise and lower it up and down the sides of the valley by locks
at a heavy expense in works, and a still greater cost in time and
water. The aqueduct is a splendid specimen of the finest class of
masonry, and Telford showed himself a master of his profession by
the manner in which he carried out the whole details of the
undertaking.  The piers were carried up solid to a certain height,
above which they were built hollow, with cross walls.  The spandrels
also, above the springing of the arches, were constructed with
longitudinal walls, and left hollow.*[3]  The first stone was laid
on the 17th of June, 1796, and the work was completed in the year
1801; the whole remaining in a perfect state to this day.

The other great aqueduct on the Ellesmere Canal, named Pont-Cysylltau,
is of even greater dimensions, and a far more striking object in
the landscape.  Sir Walter Scott spoke of it to Southey as "the
most impressive work of art he had ever seen."  It is situated about
four miles to the north of Chirk, at the crossing of the Dee, in
the romantic vale of Llangollen.  The north bank of the river is
very abrupt; but on the south side the acclivity is more gradual.
The lowest part of the valley in which the river runs is 127 feet
beneath the water-level of the canal; and it became a question with
the engineer whether the valley was to be crossed, as originally
intended, by locking down one side and up the other--which would
have involved seven or eight locks on each side--or by carrying it
directly across by means of an aqueduct.

The execution of the proposed locks would have been very costly,
and the working of them in carrying on the navigation would
necessarily have involved a great waste of water, which was a
serious objection, inasmuch as the supply was estimated to be no
more than sufficient to provide for the unavoidable lockage and
leakage of the summit level.  Hence Telford was strongly in favour
of an aqueduct; but, as we have already seen in the case of that at
Chirk, the height of the work was such as to render it impracticable
to construct it in the usual manner, upon masonry piers and arches
of sufficient breadth and strength to afford room for a puddled
water-way, which would have been extremely hazardous as well as
expensive.  He was therefore under the necessity of contriving some
more safe and economical method of procedure; and he again resorted
to the practice which he had adopted in the construction of the
Chirk Aqueduct, but on a much larger scale.

[Image] Pont-Cyslltau--Side view of Cast Iron Trough

It will be understood that many years elapsed between the period at
which Telford was appointed engineer to the Ellesmere Canal and the
designing of these gigantic works.  He had in the meantime been
carefully gathering experience from a variety of similar
undertakings on which he was employed, and bringing his
observations of the strength of materials and the different forms
of construction to bear upon the plans under his consideration for
the great aqueducts of Chirk and Pont-Cysylltau.  In 1795 he was
appointed engineer to the Shrewsbury Canal, which extends from that
town to the collieries and ironworks in the neighbourhood of
Wrekin, crossing the rivers Roden and Tern, and Ketley Brook, after
which it joins the Dorrington and Shropshire Canals.  Writing to his
Eskdale friend, Telford said : "Although this canal is only
eighteen miles long, yet there are many important works in its
course--several locks, a tunnel about half a mile long, and two
aqueducts.  For the most considerable of these last, I have just
recommended an aqueduct of iron.  It has been approved, and will be
executed under my direction, upon a principle entirely new, and
which I am endeavouring to establish with regard to the application
of iron."*[4]

It was the same principle which he applied to the great aqueducts
of the Ellesmere Canal now under consideration.  He had a model made
of part of the proposed aqueduct for Pont-Cysylltau, showing the
piers, ribs, towing-path, and side railing, with a cast iron trough
for the canal.  The model being approved, the design was completed;
the ironwork was ordered for the summit, and the masonry of the
piers then proceeded.  The foundation-stone was laid on the 25th
July, 1795, by Richard Myddelton, Esq., of Chirk Castle, M.P., and
the work was not finished until the year 1803,--thus occupying a
period of nearly eight years in construction.

The aqueduct is approached on the south side by an embankment 1500
feet in length, extending from the level of the water-way in the
canal until its perpendicular height at the "tip" is 97 feet;
thence it is carried to the opposite side of the valley, over the
river Dee, upon piers supporting nineteen arches, extending to the
length of 1007 feet.  The height of the piers above low water in the
river is 121 feet.  The lower part of each was built solid for 70
feet, all above being hollow, for the purpose of saving masonry as
well as ensuring good workmanship.  The outer walls of the hollow
portion are only two feet thick, with cross inner walls.  As each
stone was exposed to inspection, and as both Telford and his
confidential foreman, Matthew Davidson,*[5] kept a vigilant eye
upon the work, scamping was rendered impossible, and a first-rate
piece of masonry was the result.

[Image] Pont-Cyslltau Aqueduct

Upon the top of the masonry was set the cast iron trough for the
canal, with its towing-path and side-rails, all accurately fitted
and bolted together, forming a completely water-tight canal, with a
water-way of 11 feet 10 inches, of which the towing-path, standing
upon iron pillars rising from the bed of the canal, occupied 4 feet
8 inches, leaving a space of 7 feet 2 inches for the boat.*[6]
The whole cost of this part of the canal was 47,018L., which was
considered by Telford a moderate sum compared with what it must
have cost if executed after the ordinary manner.  The aqueduct was
formally opened for traffic in 1805.  "And thus," said Telford, "has
been added a striking feature to the beautiful vale of Llangollen,
where formerly was the fastness of Owen Glendower, but which, now
cleared of its entangled woods, contains a useful line of
intercourse between England and Ireland; and the water drawn from
the once sacred Devon furnishes the means of distributing
prosperity over the adjacent land of the Saxons."

[Image] Section of Top of Pont-Cyslltau Aqueduct.

It is scarcely necessary to refer to the other works upon this
canal, some of which were of considerable magnitude, though they
may now seem dwarfed by comparison with the works of recent
engineers, Thus, there were two difficult tunnels cut through hard
rock, under the rugged ground which separates the valleys of the
Dee and the Ceriog.  One of these is 500 and the other 200 yards in
length.  To ensure a supply of water for the summit of the canal,
the lake called Bala Pool was dammed up by a regulating weir, and
by its means the water was drawn off at Llandisilio when required
for the purposes of the navigation; the navigable feeder being six
miles long, carried along the bank of the Llangollen valley.
All these works were skilfully executed; and when the undertaking
was finished, Mr. Telford may be said to have fairly established
his reputation as an engineer of first rate ability.

We now return to Telford's personal history during this important
period of his career.  He had long promised himself a visit to his
dear Eskdale, and the many friends he had left there; but more
especially to see his infirm mother, who had descended far into the
vale of years, and longed to see her son once more before she died.
He had taken constant care that she should want for nothing.
She formed the burden of many of his letters to Andrew Little.
"Your kindness in visiting and paying so much attention to her,"
said he, "is doing me the greatest favour which you could possibly
confer upon me."  He sent his friend frequent sums of money, which
he requested him to lay out in providing sundry little comforts for
his mother, who seems to have carried her spirit of independence so
far as to have expressed reluctance to accept money even from her
own son.  "I must request," said he, "that you will purchase and
send up what things may be likely to be wanted, either for her or
the person who may be with her, as her habits of economy will
prevent her from getting plenty of everything, especially as she
thinks that I have to pay for it, which really hurts me more than
anything else."*[7]  Though anxious to pay his intended visit, he
was so occupied with one urgent matter of business and another that
he feared it would be November before he could set out.  He had to
prepare a general statement as to the navigation affairs for a
meeting of the committee; he must attend the approaching Salop
quarter sessions, and after that a general meeting of the Canal
Company; so that his visit must be postponed for yet another month.
"Indeed," said he, "I am rather distressed at the thoughts of
running down to see a kind parent in the last stage of decay, on
whom I can only bestow an affectionate look, and then leave her:
her mind will not be much consoled by this parting, and the
impression left upon mine will be more lasting; than pleasant."*[8]

He did, however, contrive to run down to Eskdale in the following
November.  His mother was alive, but that was all.  After doing what
he could for her comfort, and providing that all her little wants
were properly attended to, he hastened back to his responsible
duties in connection with the Ellesmere Canal.  When at Langholm,
he called upon his former friends to recount with them the incidents
of their youth.  He was declared to be the same "canty" fellow as
ever, and, though he had risen greatly in the world, he was "not a
bit set up."  He found one of his old fellow workmen, Frank Beattie,
become the principal innkeeper of the place.  "What have you made of
your mell and chisels?" asked Telford.  "Oh!" replied Beattie,
"they are all dispersed--perhaps lost."  "I have taken better care
of mine," said Telford; "I have them all locked up in a room at
Shrewsbury, as well as my old working clothes and leather apron:
you know one can never tell what may happen."

He was surprised, as most people are who visit the scenes of their
youth after a long absence, to see into what small dimensions
Langholm had shrunk.  That High Street, which before had seemed so
big, and that frowning gaol and court-house in the Market Place,
were now comparatively paltry to eyes that had been familiar with
Shrewsbury, Portsmouth, and London.  But he was charmed, as ever,
with the sight of the heather hills and the narrow winding valley--

   "Where deep and low the hamlets lie
    Beneath their little patch of sky,
    And little lot of stars."

On his return southward, he was again delighted by the sight of old
Gilnockie Castle and the surrounding scenery.  As he afterwards
wrote to his friend Little, "Broomholm was in all his glory."
Probably one of the results of this visit was the revision of the
poem of 'Eskdale,' which he undertook in the course of the
following spring, putting in some fresh touches and adding many new
lines, whereby the effect of the whole was considerably improved.
He had the poem printed privately, merely for distribution amongst
friends; being careful," as he said, that "no copies should be
smuggled and sold."

Later in the year we find him, on his way to London on business,
sparing a day or two for the purpose of visiting the Duke of
Buckingham's palace and treasures of art at Stowe; afterwards
writing out an eight-page description of it for the perusal of his
friends at Langholm.  At another time, when engaged upon the viaduct
at Pont-Cysylltau, he snatched a few day's leisure to run through
North Wales, of which he afterwards gave a glowing account to his
correspondent.  He passed by Cader Idris, Snowdon, and Penmaen Mawr.
"Parts of the country we passed through," he says, "very much
resemble the lofty green hills and woody vales of Eskdale.  In other
parts the magnificent boldness of the mountains, the torrents,
lakes, and waterfalls, give a special character to the scenery,
unlike everything of the kind I had before seen.  The vale of
Llanrwst is peculiarly beautiful and fertile.  In this vale is the
celebrated bridge of Inigo Jones; but what is a much more
delightful circumstance, the inhabitants of the vale are the most
beautiful race of people I have ever beheld; and I am much
astonished that this never seems to have struck the Welsh tourists.
The vale of Llangollen is very fine, and not the least interesting
object in it, I can assure you, is Davidson's famous aqueduct
[Pont-Cysylltau], which is already reckoned among the wonders of
Wales.  Your old acquaintance thinks nothing of having three or
four carriages at his door at a time."*[9]  It seems that, besides
attending to the construction of the works, Telford had to
organise the conduct of the navigation at those points at which the
canal was open for traffic.  By the middle of 1797 he states that
twenty miles were in working condition, along which coal and lime
were conveyed in considerable quantifies, to the profit of the
Company and the benefit of the public; the price of these articles
having already in some places been reduced twenty-five, and in
others as much as fifty, per cent.  "The canal affairs," he says in
one of his letters, "have required a good deal of exertion, though
we are on the whole doing well.  But, besides carrying on the
works, it is now necessary to bestow considerable attention on the
creating and guiding of a trade upon those portions which are
executed.  This involves various considerations, and many
contending and sometimes clashing interests.  In short, it is the
working of a great machine: in the first place, to draw money out
of the pockets of a numerous proprietary to make an expensive
canal, and then to make the money return into their pockets by the
creation of a business upon that canal."  But, as if all this
business were not enough, he was occupied at the same time in
writing a book upon the subject of Mills.  In the year 1796 he had
undertaken to draw up a paper on this topic for the Board of
Agriculture, and by degrees it had grown into a large quarto
volume, illustrated by upwards of thirty plates.  He was also
reading extensively in his few leisure moments; and among the solid
works which he perused we find him mentioning Robertson's
'Disquisitions on Ancient India,' Stewart's 'Philosophy of the
Human Mind,' and Alison's 'Principles of Taste.'  As a relief from
these graver studies, he seems, above all things, to have taken
peculiar pleasure" In occasionally throwing off a bit of
poetry.  Thus, when laid up at an hotel in Chester by a blow on his
leg, which disabled him for some weeks, he employed part of his
time in writing his 'Verses on hearing of the Death of Robert
Burns.' On another occasion, when on his way to London, and
detained for a night at Stratford-on-Avon, he occupied the evening
at his inn in composing some stanzas, entitled 'An Address to the
River Avon.' And when on his way back to Shrewsbury, while resting
for the night at Bridgenorth, he amused himself with revising and
copying out the verses for the perusal of Andrew Little.
"There are worse employments," he said,"when one has an hour to
spare from business;" and he asked his friend's opinion of the
composition.  It seems to have been no more favourable than the
verses deserved; for, in his next letter, Telford says, "I think
your observation respecting the verses to the Avon are correct.
It is but seldom I have time to versify; but it is to me something
like what a fiddle is to others, I apply to it in order to relieve
my mind, after being much fatigued with close attention to
business."

It is very pleasant to see the engineer relaxing himself in this
way, and submitting cheerfully to unfavourable criticism, which is
so trying to even the best of tempers.  The time, however, thus
taken from his regular work was not loss, but gain.  Taking the
character of his occupation into account, it was probably the best
kind of relaxation he could have indulged in.  With his head full of
bridges and viaducts, he thus kept his heart open to the influences
of beauty in life and nature; and, at all events, the writing of
verses, indifferent though they might have been, proved of this
value to him--that it cultivated in him the art of writing better
prose.

Footnotes for Chapter VI.

*[1] The Ellesmere Canal now pays about 4 per cent. dividend.

*[2] 'A General History of Inland Navigation, Foreign and
Domestic,' &c. By J. Phillips.  Fourth edition.  London, 1803.

*[3] [Image] Section of Pier

Telford himself thus modestly describes the merit of this original
contrivance: "Previously to this time such canal aqueducts had been
uniformly made to retain the water necessary for navigation by
means of puddled earth retained by masonry; and in order to obtain
sufficient breadth for this superstructure, the masonry of the
piers, abutments, and arches was of massive strength; and after all
this expense, and every imaginable precaution, the frosts, by
swelling the moist puddle, frequently created fissures, which burst
the masonry, and suffered the water to escape--nay, sometimes
actually threw down the aqueducts; instances of this kind having
occurred even in the works of the justly celebrated Brindley.
It was evident that the increased pressure of the puddled earth was
the chief cause of such failures: I therefore had recourse to the
following scheme in order to a void using it.  The spandrels of the
stone arches were constructed with longitudinal walls, instead of
being filled in with earth (as at Kirkcudbright Bridge), and across
these the canal bottom was formed by cast iron plates at each side,
infixed in square stone masonry.  These bottom plates had flanches
on their edges, and were secured by nuts and screws at every
juncture.   The sides of the canal were made water-proof by ashlar
masonry, backed with hard burnt bricks laid in Parker's cement, on
the outside of which was rubble stone work, like the rest of the
aqueduct.  The towing path had a thin bed of clay under the gravel,
and its outer edge was protected by an iron railing.  The width of
the water-way is 11 feet; of the masonry on each side, 5 feet 6
inches; and the depth of the water in the canal, 5 feet.  By this
mode of construction the quantity of masonry is much diminished,
and the iron bottom plate forms a continuous tie, preventing the
side-walls from separation by lateral pressure of the contained
water."--'Life of Telford,' p. 40.

*[4] Letter to Mr. Andrew Little, Langholm, dated Shrewsbury,
13th March, 1795.

*[5] Matthew Davidson had been Telford's fellow workman at Langholm,
and was reckoned an excellent mason.  He died at Inverness,
where he had a situation on the Caledonian Canal.

*[6] Mr. Hughes, C.E., in his 'Memoir of William Jessop,' published
in 'Weale's Quarterly Papers on Engineering,' points out the bold
and original idea here adopted, of constructing a water-tight
trough of cast iron, in which the water of the canal was to be
carried over the valleys, instead of an immense puddled trough,
in accordance with the practice until that time in use; and he adds,
"the immense importance of this improvement on the old practice is
apt to be lost sight of at the present day by those who overlook
the enormous size and strength of masonry which would have been
required to support a puddled channel at the height of 120 feet."
Mr. Hughes, however, claims for Mr. Jessop the merit of having
suggested the employment of iron, though, in our opinion, without
sufficient reason.

Mr. Jessop was, no doubt, consulted by Mr. Telford on the subject;
but the whole details of the design, as well as the suggestion of
the use of iron (as admitted by Mr. Hughes himself), and the
execution of the entire works, rested with the acting engineer.
This is borne out by the report published by the Company
immediately after the formal opening of the Canal in 1805, in which
they state: "Having now detailed the particulars relative to the
Canal, and the circumstances of the concern, the committee, in
concluding their report, think it but justice due to Mr. Telford to
state that the works have been planned with great skill and
science, and executed with much economy and stability, doing him,
as well as those employed by him, infinite credit.  (Signed)
Bridgewater."

*[7] Letter to Mr. Andrew Little, Langholm, dated Shrewsbury,
16th Sept., 1794.

*[8] lbid.

*[9] Letter to Mr. Andrew Little, Langholm, dated Salop, 20th Aug.,
1797.


CHAPTER VII.

IRON AND AND OTHER BRIDGES.

Shrewsbury being situated in the immediate neighbourhood of the
Black Country, of which coal and iron are the principal products,
Telford's attention was naturally directed, at a very early period,
to the employment of cast iron in bridge-building.  The strength as
well as lightness of a bridge of this material, compared with one
of stone and lime, is of great moment where headway is ofimportance,
or the difficulties of defective foundations have to be encountered.
The metal can be moulded in such precise forms and so accurately
fitted together as to give to the arching the greatest possible
rigidity; while it defies the destructive influences of time and
atmospheric corrosion with nearly as much certainty as stone itself.

The Italians and French, who took the lead in engineering down almost
to the end of last century, early detected the value of this material,
and made several attempts to introduce it in bridge-building;
but their efforts proved unsuccessful, chiefly because of the
inability of the early founders to cast large masses of iron,
and also because the metal was then more expensive than either stone
or timber.  The first actual attempt to build a cast iron bridge was
made at Lyons in 1755, and it proceeded so far that one of the
arches was put together in the builder's yard; but the project was
abandoned as too costly, and timber was eventually used.

It was reserved for English manufacturers to triumph over the
difficulties which had baffled the foreign iron-founders.  Shortly
after the above ineffectual attempt had been made, the construction
of a bridge over the Severn near Broseley formed the subject of
discussion among the adjoining owners.  There had been a great
increase in the coal, iron, brick, and pottery trades of the
neighbourhood; and the old ferry between the opposite banks of the
river was found altogether inadequate for the accommodation of the
traffic.  The necessity for a bridge had long been felt, and the
project of constructing one was actively taken up in 1776 by
Mr. Abraham Darby, the principal owner of the extensive iron works
at Coalbrookdale.  Mr. Pritchard, a Shrewsbury architect, prepared
the design of a stone bridge of one arch, in which he proposed to
introduce a key-stone of cast iron, occupying only a few feet at
the crown of the arch.  This plan was, however, given up as
unsuitable; and another, with the entire arch of cast iron, was
designed under the superintendence of Mr. Darby.  The castings were
made in the works at Coalbrookdale, and the bridge was erected at a
point where the banks were of considerable height on both sides of
the river.  It was opened for traffic in 1779, and continues a most
serviceable structure to this day, giving the name to the town of
Ironbridge, which has sprung up in its immediate vicinity.  The
bridge consists of one semicircular arch, of 100 feet span, each of
the great ribs consisting of two pieces only.  Mr. Robert Stephenson
has said of the structure--"If we consider that the manipulation of
cast iron was then completely in its infancy, a bridge of such
dimensions was doubtless a bold as well as an original undertaking,
and the efficiency of the details is worthy of the boldness of the
conception."*[1]

[Image] The first Iron Bridge, Coalbrookdale.

It is a curious circumstance that the next projector of an iron
bridge--and that of a very bold design--was the celebrated, or
rather the notorious, Tom Paine, whose political writings Telford
had so much admired.  The son of a decent Quaker of Thetford, who
trained him to his own trade of a staymaker, Paine seems early to
have contracted a dislike for the sect to which his father
belonged.  Arrived at manhood, he gave up staymaking to embrace the
wild life of a privateersman, and served in two successive
adventures.  Leaving the sea, he became an exciseman, but retained
his commission for only a year.  Then he became an usher in a
school, during which he studied mechanics and mathematics.  Again
appointed an exciseman, he was stationed at Lewes in Sussex, where
he wrote poetry and acquired some local celebrity as a writer.
He was accordingly selected by his brother excisemen to prepare their
petition to Government for an increase of pay, *[2] -- the document
which he drew up procuring him introductions to Goldsmith and
Franklin, and dismissal from his post.  Franklin persuaded him to go
to America; and there the quondam staymaker, privateersman, usher,
poet, an a exciseman, took an active part in the revolutionary
discussions of the time, besides holding the important office of
Secretary to the Committee for Foreign Affairs.  Paine afterwards
settled for a time at Philadelphia, where he occupied himself with
the study of mechanical philosophy, electricity, mineralogy, and
the use of iron in bridge-building.  In 1787, when a bridge over
the Schnylkill was proposed, without any river piers, as the stream
was apt to be choked with ice in the spring freshets, Paine boldly
offered to build an iron bridge with a single arch of 400 feet
span.  In the course of the same year, he submitted his design of
the proposed bridge to the Academy of Sciences at Paris; he also
sent a copy of his plan to Sir Joseph Banks for submission to the
Royal Society; and, encouraged by the favourable opinions of
scientific men, he proceeded to Rotherham, in Yorkshire, to have
his bridge cast.*[3]  An American gentleman, named Whiteside, having
advanced money to Paine on security of his property in the States,
to enable the bridge to be completed, the castings were duly made,
and shipped off to London, where they were put together and
exhibited to the public on a bowling-green at Paddington.
The bridge was there visited by a large number of persons, and was
considered to be a highly creditable work. Suddenly Paine's attention
was withdrawn from its further prosecution by the publication of
Mr. Burke's celebrated 'Thoughts on the French Revolution,' which
he undertook to answer.  Whiteside having in the meantime become
bankrupt, Paine was arrested by his assignees, but was liberated by
the assistance of two other Americans, who became bound for him.
Paine, however, was by this time carried away by the fervour of the
French Revolution, having become a member of the National
Convention, as representative for Calais.  The "Friends of Man,"
whose cause he had espoused, treated him scurvily, imprisoning him
in the Luxembourg, where he lay for eleven months.  Escaped to
America, we find him in 1803 presenting to the American Congress a
memoir on the construction of Iron Bridges, accompanied by several
models.  It does not appear, however, that Paine ever succeeded in
erecting an iron bridge.  He was a restless, speculative, unhappy
being; and it would have been well for his memory if, instead of
penning shallow infidelity, he had devoted himself to his original
idea of improving the communications of his adopted country.
In the meantime, however, the bridge exhibited at Paddington had
produced important results. The manufacturers agreed to take it
back as part of their debt, and the materials were afterwards used
in the construction of the noble bridge over the Wear at Sunderland,
which was erected in 1796.

The project of constructing a bridge at this place, where the rocky
banks of the Wear rise to a great height oh both sides of the
river, is due to Rowland Burdon, Esq., of Castle Eden, under whom
Mr. T. Wilson served as engineer in carrying out his design.
The details differed in several important respects from the proposed
bridge of Paine, Mr. Burdon introducing several new and original
features, more particularly as regarded the framed iron panels
radiating towards the centre in the form of voussoirs, for the
purpose of resisting compression.  Mr. Phipps, C.E., in a report
prepared by him at the instance of the late Robert Stephenson,
under whose superintendence the bridge was recently repaired,
observes, with respect to the original design,--"We should probably
make a fair division of the honour connected with this unique
bridge, by conceding to Burdon all that belongs to a careful
elaboration and improvement upon the designs of another, to the
boldness of taking upon himself the great responsibility of
applying.  this idea at once on so magnificent a scale, and to his
liberality and public spirit in furnishing the requisite funds
[to the amount of 22,000L.]; but we must not deny to Paine the credit
of conceiving the construction of iron bridges of far larger span
than had been made before his time, or of the important examples
both as models and large constructions which he caused to be made
and publicly exhibited.  In whatever shares the merit of this great
work may be apportioned, it must be admitted to be one of the
earliest and greatest triumphs of the art of bridge construction."
Its span exceeded that of any arch then known, being 236 feet, with
a rise of 34 feet, the springing commencing at 95 feet above the
bed of the river; and its height was such as to allow vessels of
300 tons burden to sail underneath without striking their masts.
Mr. Stephenson characterised the bridge as "a structure which, as
regards its proportions and the small quantity of material employed
in its construction, will probably remain unrivalled."

[Image] Wear Bridge, at Sunderland.

The same year in which Burdon's Bridge was erected at Sunderland,
Telford was building his first iron bridge over the Severn at
Buildwas, at a point about midway between Shrewsbury and Bridgenorth.
An unusually high flood having swept away the old bridge in the
Year 1795, he was called upon, as surveyor for the county, to
supply the plan of a new one.  Having carefully examined the bridge
at Coalbrookdale, and appreciated its remarkable merits, he
determined to build the proposed bridge at Buildwas of iron; and as
the waters came down with great suddenness from the Welsh mountains,
he further resolved to construct it of only one arch, so as to
afford the largest possible water-way.

He had some difficulty in inducing the Coalbrookdale iron-masters,
who undertook the casting of the girders, to depart from the plan
of the earlier structure; but he persisted in his design, which was
eventually carried out.  It consisted of a single arch of 130 feet
span, the segment of a very large circle, calculated to resist the
tendency of the abutments to slide inwards, which had been a defect
of the Coalbrookdale bridge; the flat arch being itself sustained
and strengthened by an outer ribbed one on each side, springing
lower than the former and also rising higher, somewhat after the
manner of timber-trussing.  Although the span of the new bridge was
30 feet wider than the Coalbrookdale bridge, it contained less than
half the quantity of iron; Buildwas bridge containing 173, whereas
the other contained 378 tons.  The new structure was, besides,
extremely elegant in form; and when the centres were struck, the
arch and abutments stood perfectly firm, and have remained so to
this day.  But the ingenious design of this bridge will be better
explained by the following representation than by any description
in words.*[4]  The bridge at Buildwas, however, was not Telford's
first employment of iron in bridge-building; for, the year before
its erection, we find him writing to his friend at Langholm that he
had recommended an iron aqueduct for the Shrewsbury Canal,
"on a principle entirely new," and which he was "endeavouring to
establish with regard to the application of iron."*[5]  This iron
aqueduct had been cast and fixed; and it was found to effect so
great a saving in masonry and earthwork, that he was afterwards
induced to apply the same principle, as we have already seen,
in different forms, in the magnificent aqueducts of Chirk and
Pont-Cysylltau.

The uses of cast iron in canal construction became more obvious
with every year's successive experience; and Telford was accustomed
to introduce it in many cases where formerly only timber or stone
had been used.  On the Ellesmere, and afterwards on the Caledonial
Canal, he adopted cast iron lock-gates, which were found to answer
well, being more durable than timber, and not liable like it to
shrink and expand with alternate dryness and wet.  The turnbridges
which he applied to his canals, in place of the old drawbridges,
were also of cast iron; and in some cases even the locks were of
the same material.  Thus, on a part of the Ellesmere Canal opposite
Beeston Castle, in Cheshire, where a couple of locks, together
rising 17 feet, having been built on a stratum of quicksand, were
repeatedly undermined, the idea of constructing the entire locks of
cast iron was suggested; and this unusual application of the new
material was accomplished with entirely satisfactory results.

But Telford's principal employment of cast iron was in the
construction of road bridges, in which he proved himself a master.
His experience in these structures had become very extensive.
During the time that he held the office of surveyor to the county
of Salop, he erected no fewer than forty-two, five of which were of
iron.  Indeed, his success in iron bridge-building so much
emboldened him, that in 1801, when Old London Bridge had become so
rickety and inconvenient that it was found necessary to take steps
to rebuild or remove it, he proposed the daring plan of a cast iron
bridge of a single arch of not less than 600 feet span, the segment
of a circle l450 feet in diameter.  In preparing this design we
find that he was associated with a Mr. Douglas, to whom many
allusions are made in his private letters.*[6]  The design of this
bridge seems to have arisen out of a larger  project for the
improvement of the port of London.  In a private letter of Telford's,
dated the 13th May, 1800, he says:

"I have twice attended the Select Committee on the Fort of London,
Lord Hawkesbury, Chairman.  The subject has now been agitated for
four years, and might have been so for many more, if Mr. Pitt had
not taken the business out of the hands of the General Committee,
and got it referred to a Select Committee.  Last year they
recommended that a system of docks should be formed in a large bend
of the river opposite Greenwich, called the Isle of Dogs, with a
canal across the neck of the bend.  This part of the contemplated
improvements is already commenced, and is proceeding as rapidly as
the nature of the work will admit.  It will contain ship docks for
large vessels, such as East and West Indiamen, whose draught of
water is considerable.

"There are now two other propositions under consideration.  One is
to form another system of docks at Wapping, and the other to take
down London Bridge, rebuild it of such dimensions as to admit of
ships of 200 tons passing under it, and form a new pool for ships
of such burden between London and Blackfriars Bridges, with a set
of regular wharves on each side of the river.  This is with the view
of saving lighterage and plunderage, and bringing the great mass of
commerce so much nearer to the heart of the City.  This last part of
the plan has been taken up in a great measure from some statements
I made while in London last year, and I have been called before the
Committee to explain.  I had previously prepared a set of plans and
estimates for the purpose of showing how the idea might be carried
out; and thus a considerable degree of interest has been excited on
the subject.  It is as yet, however, very uncertain how far the
plans will be carried out.  It is certainly a matter of great
national importance to render the Port of London as perfect as
possible."*[7]

Later in the same year he writes that his plans and propositions
have been approved and recommended to be carried out, and he
expects to have the execution of them.  "If they will provide the
ways and means," says he, "and give me elbow-room, I see my way as
plainly as mending the brig at the auld burn."  In November, 1801,
he states that his view of London Bridge, as proposed by him, has
been published, and much admired.  On the l4th of April, 1802, he
writes, "I have got into mighty favour with the Royal folks.  I have
received notes written by order of the King, the Prince of Wales,
Duke of York, and Duke of Kent, about the bridge print, and in
future it is to be dedicated to the King."

The bridge in question was one of the boldest of Telford's designs.
He proposed by his one arch to provide a clear headway of 65 feet
above high water.  The arch was to consist of seven cast iron ribs,
in segments as large as possible, and they were to be connected by
diagonal cross-bracing, disposed in such a manner that any part of
the ribs and braces could be taken out and replaced without injury
to the stability of the bridge or interruption to the traffic over it.
The roadway was to be 90 feet wide at the abutments and 45 feet
in the centre; the width of the arch being gradually contracted
towards the crown in order to lighten the weight of the structure.
The bridge was to contain 6500 tons of iron, and the cost of the
whole was to be 262,289L.

[Image] Telford's proposed One-arched Bridge over the Thames.

The originality of the design was greatly admired, though there
were many who received with incredulity the proposal to bridge the
Thames by a single arch, and it was sarcastically said of Telford
that he might as well think of "setting the Thames on fire."
Before any outlay was incurred in building the bridge, the design
was submitted to the consideration of the most eminent scientific
and practical men of the day; after which evidence was taken at
great length before a Select Committee which sat on the subject.
Among those examined on the occasion were the venerable James Watt
of Birmingham, Mr. John Rennie, Professor Button of Woolwich,
Professors Playfair and Robison of Edinburgh, Mr. Jessop,
Mr.Southern, and Dr. Maskelyne.  Their evidence will still be found
interesting as indicating the state at which constructive science
had at that time arrived in England.*[8]  There was a considerable
diversity of opinion among the witnesses, as might have been
expected; for experience was as yet very limited as to the
resistance of cast iron to extension and compression.  Some of them
anticipated immense difficulty in casting pieces of metal of the
necessary size and exactness, so as to secure that the radiated
joints should be all straight and bearing.  Others laid down certain
ingenious theories of the arch, which did not quite square with the
plan proposed by the engineer.  But, as was candidly observed by
Professor Playfair in concluding his report--"It is not from
theoretical men that the most valuable information in such a case
as the present is to be expected.  When a mechanical arrangement
becomes in a certain degree complicated, it baffles the efforts of
the geometer, and refuses to submit to even the most approved
methods of investigation.  This holds good particularly of bridges,
where the principles of mechanics, aided by all the resources of
the higher geometry, have not yet gone further than to determine
the equilibrium of a set of smooth wedges acting on one another by
pressure only, and in such circumstances as, except in a
philosophical experiment, can hardly ever be realised.  It is,
therefore, from men educated in the school of daily practice and
experience, and who to a knowledge of general principles have
added, from the habits of their profession, a certain feeling of
the justness or insufficiency of any mechanical contrivance, that
the soundest opinions on a matter of this kind can be obtained."

It would appear that the Committee came to the general conclusion
that the construction of the proposed bridge was practicable and
safe; for the river was contracted to the requisite width, and the
preliminary works were actually begun.  Mr. Stephenson says the
design was eventually abandoned, owing more immediately to the
difficulty of constructing the approaches with such a head way,
which would have involved the formation of extensive inclined
planes from the adjoining streets, and thereby led to serious
inconvenience, and the depreciation of much valuable property on
both sides of the river.*[9]  Telford's noble design of his great
iron bridge over the Thames, together with his proposed embankment
of the river, being thus definitely abandoned, he fell back upon
his ordinary business as an architect and engineer, in the course
of which he designed and erected several stone bridges of
considerable magnitude and importance.

In the spring of 1795, after a long continued fall of snow, a
sudden thaw raised a heavy flood in the Severn, which carried away
many bridges--amongst others one at Bewdley, in Worcestershire,--
when Telford was called upon to supply a design for a new structure.
At the same time, he was required to furnish a plan for a new
bridge near the town of Bridgenorth; "in short," he wrote to his
friend, "I have been at it night and day."  So uniform a success had
heretofore attended the execution of his designs, that his
reputation as a bridge-builder was universally acknowledged.
"Last week," he says, "Davidson and I struck the centre of an arch
of 76 feet span, and this is the third which has been thrown this
summer, none of which have shrunk a quarter of an inch."

Bewdley Bridge is a handsome and substantial piece of masonry.
The streets on either side of it being on low ground, land arches
were  provided at both ends for the passage of the flood waters;
and as the Severn was navigable at the point crossed, it was
considered necessary to allow considerably greater width in the
river arches than had been the case in the former structure.
The arches were three in number--one of 60 feet span and two of 52
feet, the land arches being of 9 feet span.  The works were
proceeded with and the bridge was completed during the summer of
1798, Telford writing to his friend in December of that year--
"We have had a remarkably dry summer and autumn; after that an early
fall of snow and some frost, followed by rain.  The drought of the
summer was unfavourable to our canal working; but it has enabled us
to raise Bewdley Bridge as if by enchantment.  We have thus built a
magnificent bridge over the Severn in one season, which is no
contemptible work for John Simpson*[10] and your humble servant,
amidst so many other great undertakings.  John Simpson is a
treasure--a man of great talents and integrity.  I met with him
here by chance, employed and recommended him, and he has now under
his charge all the works of any magnitude in this great and rich
district."

[Image] Bewdley Bridge.

Another of our engineer's early stone bridges, which may be
mentioned in this place, was erected by him in 1805, over the river
Dee at Tongueland in the county of Kirkcudbright.  It is a bold and
picturesque bridge, situated in a lovely locality.  The river is
very deep at high water there, the tide rising 20 feet.  As the
banks were steep and rocky, the engineer determined to bridge the
stream by a single arch of 112 feet span.  The rise being
considerable, high wingwalls and deep spandrels were requisite; but
the weight of the structure was much lightened by the expedient
which he adopted of perforating the wings, and building a number of
longitudinal walls in the spandrels, instead of filling them with
earth or inferior masonry, as had until then been the ordinary
practice.  The ends of these walls, connected and steadied by the
insertion of tee-stones, were built so as to abut against the back
of the arch-stones and the cross walls of each abutment.  Thus great
strength as well as lightness was secured, and a very graceful and
at the same time substantial bridge was provided for the
accommodation of the district.*[11]

[Image] Tongueland Bridge.

In his letters written about this time, Telford seems to have been
very full of employment, which required him to travel about a great
deal.  "I have become," said he, "a very wandering being, and am
scarcely ever two days in one place, unless detained by business,
which, however, occupies my time very completely."  At another time
he says, "I am tossed about like a tennis ball: the other day I was
in London, since that I have been in Liverpool, and in a few days I
expect to be at Bristol.  Such is my life; and to tell you the
truth, I think it suits my disposition."

Another work on which Telford was engaged at this time was a
project for supplying the town of Liverpool with water conveyed
through pipes in the same manner as had long before been adopted in
London.  He was much struck by the activity and enterprise apparent
in Liverpool compared with Bristol.  "Liverpool," he said,
"has taken firm root in the country by means of the canals"
it is young, vigorous, and well situated.  Bristol is sinking in
commercial importance: its merchants are rich and indolent, and in
their projects they are always too late.  Besides, the place is
badly situated.  There will probably arise another port there
somewhat nearer the Severn; but Liverpool will nevertheless
continue of the first commercial importance, and their water will
be turned into wine.  We are making rapid progress in this country--
I mean from Liverpool to Bristol, and from Wales to Birmingham.
This is an extensive and rich district, abounding in coal, lime,
iron, and  lead.  Agriculture too is improving, and manufactures
are advancing at rapid strides towards perfection.  Think of such a
mass of population, industrious, intelligent, and energetic, in
continual exertion! In short, I do not believe that any part of the
world, of like dimensions, ever exceeded Great Britain, as it now
is, in regard to the production of wealth and the practice of the
useful arts."*[12]  Amidst all this progress, which so strikingly
characterized the western districts of England, Telford also
thought that there was a prospect of coming improvement for Ireland.
"There is a board of five members appointed by Parliament, to act
as a board of control over all the inland navigations, &c., of
Ireland.  One of the members is a particular friend of mine, and at
this moment a pupil, as it were, anxious for information.  This is
a noble object: the field is wide, the ground new and capable of
vast improvement.  To take up and manage the water of a fine island
is like a fairy tale, and, if properly conducted, it would render
Ireland truly a jewel among the nations."*[13]  It does not,
however, appear that Telford was ever employed by the board to
carry out the grand scheme which thus fired his engineering
imagination.

Mixing freely with men of all classes, our engineer seems to have
made many new friends and acquaintances about this time.  While on
his journeys north and south, he frequently took the opportunity of
looking in upon the venerable James Watt--"a great and good man,"
he terms him--at his house at Heathfield, near Birmingham.
At London he says he is "often with old Brodie and Black, each the
first in his profession, though they walked up together to the
great city on foot,*[14] more than half a century ago--Gloria!"
About the same time we find him taking interest in the projects of
a deserving person, named Holwell, a coal-master in Staffordshire,
and assisting him to take out a patent for boring wooden pipes;
"he being a person," says Telford, "little known, and not having
capital, interest, or connections, to bring the matter forward."