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is not above twelve feet in the steepest part of the hill； and two
carriages cannot pass without the greatest danger。 Between this
hill and Rhyddlanfair there are a number of dangerous precipices；
steep hills； and difficult narrow turnings。 From Corwen to
Llangollen the road is very narrow； long； and steep； has no side
fence； except about a foot and a half of mould or dirt； which is
thrown up to prevent carriages falling down three or four hundred
feet into the river Dee。 Stage…coaches have been frequently
overturned and broken down from the badness of the road； and the
mails have been overturned； but I wonder that more and worse
accidents have not happened； the roads are so bad。〃Evidence of
Mr。 William Akers； of the Post…office； before Committee of the
House of Commons； 1st June； 1815。
*＇6＇ The Select Committee of the House of Commons； in reporting as
to the manner in which these works were carried out； stated as
follows： 〃The professional execution of the new works upon this
road greatly surpasses anything of the same kind in these
countries。 The science which has been displayed in giving the
general line of the road a proper inclination through a country
whose whole surface consists of a succession of rocks； bogs；
ravines； rivers； and precipices； reflects the greatest credit upon
the engineer who has planned them； but perhaps a still greater
degree of professional skill has been shown in the construction； or
rather the building； of the road itself。 The great attention which
Mr。 Telford has devoted； to give to the surface of the road one
uniform and moderately convex shape； free from the smallest
inequality throughout its whole breadth； the numerous land drains；
and； when necessary； shores and tunnels of substantial masonry；
with which all the water arising from springs or falling in rain is
instantly carried off； the great care with which a sufficient
foundation is established for the road； and the quality； solidity；
and disposition of the materials that are put upon it； are matters
quite new in the system of road…making in these countries。〃
'Report from the Select Committee on the Road from London to
Holyhead in the year 1819。'
*＇7＇ Evidence of William Waterhouse before the Select Committee；
10th March； 1819。
CHAPTER XII。
THE MENAI AND CONWAY BRIDGES。
＇Image＇ Map of Menai Strait ＇Ordnance Survey＇
So long as the dangerous Straits of Menai had to be crossed in an
open ferry…boat； the communication between London and Holyhead was
necessarily considered incomplete。 While the roads through North
Wales were so dangerous as to deter travellers between England and
Ireland from using that route； the completion of the remaining link
of communication across the Straits was of comparatively little
importance。 But when those roads had； by the application of much
capital； skill； and labour； been rendered so safe and convenient
that the mail and stage coaches could run over them at the rate of
from eight to ten miles an hour； the bridging of the Straits became
a measure of urgent public necessity。 The increased traffic by this
route so much increased the quantity of passengers and luggage；
that the open boats were often dangerously overloaded； and serious
accidents； attended with loss of life and property； came to be of
frequent occurrence。
The erection of a bridge over the Straits had long been matter of
speculation amongst engineers。 As early as 1776； Mr。 Golborne
proposed his plan of an embankment with a bridge in the middle of it；
and a few years later； in 1785； Mr。 Nichols proposed a wooden
viaduct； furnished with drawbridges at Cadnant Island。 Later still；
Mr。 Rennie proposed his design of a cast iron bridge。 But none of
these plans were carried out； and the whole subject remained in
abeyance until the year 1810； when a commission was appointed to
inquire and report as to the state of the roads between Shrewsbury；
Chester； and Holyhead。 The result was； that Mr。 Telford was called
upon to report as to the most effectual method of bridging the
Menai Strait； and thus completing the communication with the port
of embarkation for Ireland。
＇Image＇ Telford's proposed Cast Iron Bridge
Mr。 Telford submitted alternative plans for a bridge over the
Strait： one at the Swilly Rock； consisting of three cast iron
arches of 260 feet span； with a stone arch of 100 feet span between
each two iron ones； to resist their lateral thrust； and another at
Ynys…y…moch； to which he himself attached the preference；
consisting of a single cast iron arch of 500 feet span； the crown
of the arch to be 100 feet above high water of spring tides； and
the breadth of the roadway to be 40 feet。
The principal objection taken to this plan by engineers generally；
was the supposed difficulty of erecting a proper centering to
support the arch during construction； and the mode by which
Mr。 Telford proposed to overcome this may be cited in illustration
of his ready ingenuity in overcoming difficulties。 He proposed to
suspend the centering from above instead of supporting it from
below in the usual mannera contrivance afterwards revived by
another very skilful engineer； the late Mr。 Brunel。 Frames； 50 feet
high； were to be erected on the top of the abutments； and on these；
strong blocks； or rollers and chains； were to be fixed； by means of
which； and by the aid of windlasses and other mechanical powers；
each separate piece of centering was to be raised into； and
suspended in； its proper place。 Mr。 Telford regarded this method of
constructing centres as applicable to stone as well as to iron
arches； and indeed it is applicable； as Mr。 Brunel held； to the
building of the arch itself。*＇1＇
＇Image＇ Proposed Plan of Suspended Centering
Mr。 Telford anticipated that； if the method recommended by him were
successfully adopted on the large scale proposed at Menai； all
difficulties with regard to carrying bridges over deep ravines
would be done away with； and a new era in bridge…building begun。
For this and other reasonsbut chiefly because of the much greater
durability of a cast iron bridge compared with the suspension
bridge afterwards adoptedit is matter of regret that he was not
permitted to carry out this novel and grand design。 It was；
however； again objected by mariners that the bridge would seriously
affect； if not destroy； the navigation of the Strait； and this
plan； like Mr。 Rennie's； was eventually rejected。
Several years passed； and during the interval Mr。 Telford was
consulted as to the construction of a bridge over Runcorn Gap on
the Mersey； above Liverpool。 As the river was there about 1200 feet
wide； and much used for purposes of navigation； a bridge of the
ordinary construction was found inapplicable。 But as he was
required to furnish a plan of the most suitable structure； he
proceeded to consider how the difficulties of the case were to be met。
The only practicable plan； he thought； was a bridge constructed on
the principle of suspension。 Expedients of this kind had long been
employed in India and America； where wide rivers were crossed by
means of bridges formed of ropes and chains； and even in this
country a suspension bridge； though of a very rude kind； had long
been in use near Middleton on the Tees； where； by means of two
common chains stretched across the river； upon which a footway of
boards was laid； the colliers were enabled to pass from their
cottages to the colliery on the opposite bank。
Captain （afterwards Sir Samuel） Brown took out a patent for forming
suspension bridges in 1817； but it appears that Telford's attention
had been directed to the subject before this time； as he was first
consulted respecting the Runcorn Bridge in the year 1814； when he
proceeded to make an elaborate series of experiments on the
tenacity of wrought iron bars； with the object of employing this
material in his proposed structure。 After he had made upwards of
two hundred tests of malleable iron of various qualities； he
proceeded to prepare his design of a bridge； which consisted of a
central opening of 1000 feet span； and two side openings of 500
feet each； supported by pyramids of masonry placed near the
low…water lines。 The roadway was to be 30 feet wide； divided into
one central footway and two distinct carriageways of 12 feet each。
At the same time he prepared and submitted a model of the central
opening； which satisfactorily stood the various strains which were
applied to it。 This Runcorn design of 1814 was of a very
magnificent character； perhaps superior even to that of the Menai
Suspension Bridge； afterwards erected； but unhappily the means were
not forthcoming to carry it into effect。 The publication of his
plan and report had； however； the effect of directing public
attention to the construction of bridges on the suspension
principle； and many were shortly after designed and erecte