Facebook Twitter Flickr      Posts Subscribe to Heritage of Wales News Blog Posts      All Comments Subscribe to Heritage of Wales News Blog Posts     Cymraeg

Thursday, 3 February 2011

Drawings of Chain Bridge by a French Industrial Spy





Pont Gadwyni Llandysilio.
The Llantisilio Chain Bridge. Llun/Image: DS2007_077_001   NPRN: 24054
Pont Gadwyni Llandysilio
Codwyd y Bont Gadwyni gyntaf ym 1817 i gysylltu dau lwybr mawr trafnidiaeth yn y Gogledd, sef camlas Llangollen a’r ffordd o Lundain i Gaergybi. Yr oedd y mentrwr lleol, Exuperius Pickering, yn awyddus i fanteisio ar Gamlas Llangollen i gludo’i nwyddau – glo, calch a barrau haearn – draw i briffordd Telford a sicrhau mynediad cyflym a rhad i farchnadoedd y gogledd. I sicrhau hynny, treuliodd gryn amser o 1814 ymlaen yn pwyso ar Gwmni Camlas Llangollen i wella darn bwydo’r gamlas a rhoi iddo ef, a neb arall, fynediad i’r ceiau a’r pontydd. Yn y pen draw, bu codi’r bont yn fodd iddo fonopoleiddio’r fasnach lo yn yr ardal honno.

Codwyd pont Pickering o ddec pren a gâi ei gynnal gan gadwyni haearn gyr oddi isod. Rhoddwyd haen o bridd a cherrig dros y dec. O wely’r afon cynhelid y bont gan chwe cholofn dderw digon o faint i wrthsefyll llifddyfroedd mawr. Gwnaed lluniadau arolygu manwl o’r bont honno gan y sbïwr diwydiannol o Ffrainc, J. Dutens, ym 1819, ac yn ei adroddiad cafwyd y sylw ‘nid oes modd rhoi terfyn ar yr athrylith... fe geir yn Llundain enghreifftiau o bontydd cadwyni, ond ôl meddwl rhagorach sydd i gynllun y bont dros Afon Dyfrdwy’. Erbyn 1870, y farn oedd bod cyflwr y bont yn rhy wael iddi gael ei hadfer ac fe’i tynnwyd oddi yno. Yn ei lle, codwyd pont ym 1876 gan Henry Robertson, peiriannydd enwog pontydd a rheilffyrdd a pherchennog gwaith haearn Brymbo. Mae’n hysbys i’w gynllun ddilyn un y bont gyntaf ond bod y colofnau a gynhaliai’r bont yn rhai o haearn yn hytrach nag o dderw.

Er i’r rhan fwyaf o’r bont gael ei golchi ymaith gan lifogydd difrifol ar 16eg Chwefror 1928, dal eu tir wnaeth ei chadwyni cynhaliol. Penderfynodd Syr Henry Robertson, mab yr Henry blaenorol, ailgodi’r bont ar batrwm Pont Menai, a dywedir iddo ailddefnyddio cadwyni’r bont wreiddiol. Crogwyd chwech o’r cadwyni hynny i gynnal y dec oddi uchod, a gosodwyd dwy arall unwaith eto o dan y dec. Gwelliant mawr oedd y cynllun hwnnw am ei fod yn gryfach ac yn gallu gwrthsefyll llifogydd. Costiodd gyfanswm o £303.11.00. Adeg agor y bont cynhaliwyd diwrnod o ddathlu a rhoddwyd 45 o’r gweithwyr i sefyll ar y bont i ddangos pa mor gryf oedd hi.

Caewyd y bont yn derfynol ganol y 1980au. Gan ei bod hi mewn cyflwr peryglus, does dim modd mynd ati ond mae ymchwil y Comisiwn wedi gallu dangos bod cynllun a graddfa’r cadwyni a ddefnyddiwyd yn y drydedd bont mor debyg nes ychwanegu cryn bwysau at y ddamcaniaeth i gadwyni’r bont wreiddiol gael eu storio a’u hailddefnyddio 111 o flynyddoedd yn ddiweddarach.

Cysylltau:

The Llantisilio Chain Bridge
The Chain Bridge was first built in 1817 in order to link two major transport routes in North Wales, the Llangollen canal and the London to Holyhead Road. Local entrepreneur, Exuperius Pickering, wished to take advantage of the Llangollen Canal to transport his goods of coal, lime and iron bar to Telfords’ highway, thereby giving him quick and cheap access to the markets in the north. To achieve this he spent considerable time from 1814 onwards petitioning the Llangollen Canal Company to improve the feeder section of canal and allow him exclusive access to the wharves and bridges. Ultimately, the construction of the bridge allowed him to monopolise the coal trade in the area.

Pickering’s bridge was constructed of wooden decking supported by wrought iron chains from below and with a covering surface of earth and stone. Six oak pillars supported the bridge from within the river bed, substantial enough to withstand heavy floodwaters. Detailed survey drawings of this bridge were carried out by the French Industrial spy, J. Dutens, in 1819 accompanied by a report that included ‘one cannot assign a limit to the genius… there exist in London examples of chain bridges, but the conception of the bridge of the Dee is preferable’. By 1870 however the condition of the bridge was considered to be beyond repair and the structure removed. It was replaced in 1876 by Henry Robertson, a renowned bridge and railway engineer, as well as an owner of the Brymbo Ironworks. His design is known to have closely followed that of the first structure, the supporting pillars being of iron rather than oak.

On 16th February 1928, severe flooding washed away the majority of the bridge, although the supporting chains held fast. Sir Henry Robertson, the previous Henry’s son, decided to rebuild the crossing along the lines of the Menai Suspension Bridge, reportedly re-using the chains from the original structure. Six of these chains were suspended to support the deck from above, while a further two again lay underneath the deck. The new design was a great improvement, being of greater strength and unaffected by floods. The total cost was £303.11.00, and the official opening was marked by a day of celebrations, including the standing of 45 employees on the bridge in order to demonstrate its strength.

This bridge was finally closed in the mid 1980s and, being in a dangerous state of repair, is inaccessible. The research carried out by Commission however, has been able to show that the design and scale of the chains used in the third structure are so similar as to lend considerable weight to the hypothesis that the chains from the original structure were stored and reused 111 years later.

Links:
Cyhoeddiadau/Publication:


BBC2 Wales - Hidden Histories - Series 3

Subscribe to the Heritage of Wales News and sign up for the full feed RSS, just click this Subscribe to Heritage of Wales News Blog Posts RRS button and subscribe!
Share this post:

0 comments:

Post a Comment

www.rcahmw.gov.uk
Please comment and let us know your views or your news. Remember that what you write can be read by everyone. RCAHMW reserves the right not to publish offensive or inaccurate material.

LinkWithin

Related Posts with Thumbnails