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plane to the depth of about twenty yards。 A considerable width of
rock lay between each tunnel； but at the bottom they were all
united by a connecting horizontal avenue or cavern； sufficiently
capacious to enable the workmen to fix the strong iron frames；
composed principally of thick flat cast iron plates； which were
engrafted deeply into the rock； and strongly bound together by the
iron work passing along the horizontal avenue； so that； if the iron
held； the chains could only yield by tearing up the whole mass of
solid rock under which they were thus firmly bound。
A similar method of anchoring the main chains was adopted on the
Caernarvonshire side。 A thick bank of earth had there to be cut
through； and a solid mass of masonry built in its place； the rock
being situated at a greater distance from the main pier； involving
a greater length of suspending chain； and a disproportion in the
catenary or chord line on that side of the bridge。 The excavation
and masonry thereby rendered necessary proved a work of vast
labour； and its execution occupied a considerable time； but by the
beginning of the year 1825 the suspension pyramids； the land piers
and arches； and the rock tunnels； had all been completed； and the
main chains were firmly secured in them； the work being
sufficiently advanced to enable the suspending of the chains to be
proceeded with。 This was by far the most difficult and anxious part
of the undertaking。
With the same careful forethought and provision for every
contingency which had distinguished the engineer's procedure in the
course of the work； he had made frequent experiments to ascertain
the actual power which would be required to raise the main chains
to their proper curvature。 A valley lay convenient for the purpose；
a little to the west of the bridge on the Anglesea side。
Fifty…seven of the intended vertical suspending rods； each nearly
ten feet long and an inch square； having been fastened together； a
piece of chain was attached to one end to make the chord line 570
feet in length； and experiments having been made and comparisons
drawn； Mr。 Telford ascertained that the absolute weight of one of
the main chains of the bridge between the points of suspension was
23 1/2 tons； requiring a strain of 39 1/2 tons to raise it to its
proper curvature。 On this calculation the necessary apparatus
required for the hoisting was prepared。 The mode of action finally
determined on for lifting the main chains； and fixing them into
their places； was to build the central portion of each upon a raft
450 feet long and 6 feet wide； then to float it to the site of the
bridge； and lift it into its place by capstans and proper tackle。
At length all was ready for hoisting the first great chain； and
about the middle of April； 1825； Mr。 Telford left London for Bangor
to superintend the operations。 An immense assemblage collected to
witness the sight； greater in number than any that had been
collected in the same place since the men of Anglesea； in their
war…paint； rushing down to the beach； had shrieked defiance across
the Straits at their Roman invaders on the Caernarvon shore。
Numerous boats arrayed in gay colours glided along the waters； the
daythe 26th of Aprilbeing bright； calm； and in every way
propitious。
At half…past two； about an hour before high water； the raft bearing
the main chain was cast off from near Treborth Mill； on the
Caernarvon side。 Towed by four boats； it began gradually to move
from the shore； and with the assistance of the tide； which caught
it at its further end； it swung slowly and majestically round to
its position between the main piers； where it was moored。 One end
of the chain was then bolted to that which hung down the face of
the Caernarvon pier； whilst the other was attached to ropes
connected with strong capstans fixed on the Anglesea side； the
ropes passing by means of blocks over the top of the pyramid of the
Anglesea pier。 The capstans for hauling in the ropes bearing the
main chain； were two in number； manned by about 150 labourers。 When
all was ready； the signal was given to 〃Go along！〃 A Band of fifers
struck up a lively tune； the capstans were instantly in motion； and
the men stepped round in a steady trot。 All went well。 The ropes
gradually coiled in。 As the strain increased； the pace slackened a
little； but 〃Heave away； now she comes！〃 was sung out。 Round went
the men； and steadily and safely rose the ponderous chain。
＇Image＇ Cut of Bridge； showing state of Suspension Chain
The tide had by this time turned； and bearing upon the side of the
raft； now getting freer of its load； the current floated it away
from under the middle of the chain still resting on it； and it
swung easily off into the water。 Until this moment a breath less
silence pervaded the watching multitude； and nothing was heard
among the working party on the Anglesea side but the steady tramp
of the men at the capstans； the shrill music of the fife； and the
occasional order to 〃Hold on！〃 or 〃Go along！〃 But no sooner was the
raft seen floating away； and the great chain safely swinging in the
air； than a tremendous cheer burst forth along both sides of the
Straits。
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 chainwhich
was only nine inches wide and formed a curvature of 590 feetfrom
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