Pont-y-Cafnau – The Melting Pot – Merthyr Tydfil's History and Culture

Grade II* Listed buildings

Fifty years ago today a number of Merthyr’s buildings were given a Grade II* listing by CADW. Below is a list of all the Grade II* listed buildings in Merthyr.

Name	Location Grid Ref. Geo-coordinates	Date Listed	Notes
Cefn Railway Viaduct	Cyfarthfa SO0304907597 51°45′31″N 3°24′22″W	7 Nov 1951	Viaduct A dual-listed (see below) structure built in 1866 to carry the Brecon and Merthyr Railway over the Taf Fawr. It was designed by Henry Conybeare and Alexander Sutherland at a cost of £25,000. The fifteen arches of the 36.6 m (120 ft) high viaduct follow a gentle curve of 235 m (771 ft).
Cefn Railway Viaduct	Vaynor SO0304007795 51°45′38″N 3°24′23″W	7 Nov 1951	Viaduct A dual-listed (see above) structure built in 1866 to carry the Brecon and Merthyr Railway over the Taf Fawr. The viaduct has tall, slender limestone piers, a material originally intended to be used throughout, however, the arches were completed using a contrasting red brick due to a trade union strike by stonemasons.
Pont-y-Cafnau	Park SO0376507138 51°45′17″N 3°23′44″W	22 August 1975	Bridge An ironwork bridge spanning the River Taff constructed in 1793. The name, meaning “bridge of troughs”, comes from its unusual three tier design of a tramroad between two watercourses, one beneath the bridge deck and the other on an upper wooden structure which is no longer present. Pont-y-Cafnau is also designated as a scheduled monument.
Town Hall	Town SO0489306371 51°44′51″N 3°22′40″W	22 August 1975	Town hall A Large municipal building designed by Edwin Arthur Johnson in the early Renaissance style and built 1896–98 by Harry Gibbon. Built of red Cattybrook brick with orange terracotta dressings on a base of Pennant Sandstone. Following restoration work it became the Red House, an arts centre, in 2014.
Pontsarn Railway Viaduct	Pant SO0454309921 51°46′47″N 3°23′06″W	22 August 1975	Viaduct A dual-listed (see below) structure built in 1866 to carry the Brecon and Merthyr Railway over the Taf Fechan. It was designed by Henry Conybeare and Alexander Sutherland. The viaduct is 28 m (92 ft) high and 128 m (420 ft) long.
Pontsarn Railway Viaduct	Vaynor SO0453409918 51°46′47″N 3°23′07″W	22 August 1975	Viaduct A dual-listed (see above) structure built in 1866 to carry the Brecon and Merthyr Railway over the Taf Fechan. It is constructed of limestone and has tall, slender piers with segmental arches. The Cadw description has seven arches, Newman has eight.
Former Guest Memorial Library	Dowlais SO0699107880 51°45′43″N 3°20′57″W	22 August 1975	Library A two-storey cruciform building of 1855–1863 built as a memorial to John Josiah Guest of the Dowlais Ironworks. The Dowlais workmen intended for the library and reading room to be funded by subscription, but rising costs led to the building being completed by the company at a total cost of £7,000.
Dowlais Works Blast Engine House	Dowlais SO0690907739 51°45′38″N 3°21′01″W	22 August 1975	Engine house A 54 m (177 ft) long and 15 m (49 ft) high red brick industrial building constructed in 1905–07 to house three blowing engines as part of the Dowlais Ironworks. The works went into decline in the 1930s and in the late 20th century the building was being used by a chocolate company.
Quakers Yard Railway Viaduct	Treharris ST0885396473 51°39′35″N 3°19′09″W	1 April 1988	Viaduct A tall stone-built viaduct with six arches that spans both the River Taff and the Merthyr Tramroad. It was constructed 1840–41 by Isambard Kingdom Brunel as part of the Taff Vale Railway and widened by 1861.
Ynysfach Engine House	Cyfarthfa SO0452406096 51°44′44″N 3°23′04″W	5 Nov 1995	Engine house Built in 1836 as part of the Ynysfach Ironworks, it originally housed an engine made at the Neath Abbey Ironworks. This four-storey building of blue Pennant Sandstone with white ashlar dressings fell into disuse when the Ynysfach works closed in 1874. In the 1980s It was restored and became a museum until closed by the Leisure Trust.
Greenfield Bridge, Penydarren Tramroad	Treharris ST0902496544 51°39′37″N 3°19′00″W	20 February 2003	Bridge A single arch Pennant Sandstone structure built to replace an earlier wooden bridge that collapsed in 1815 when a train was passing over it. The semi-circular arch has span of 19.2 m (63 ft) at a height of 8.4 m (28 ft) above the river. It is part of the Merthyr Tramroad scheduled monument.
Victoria Bridge, Penydarren Tramroad	Treharris ST0942396281 51°39′29″N 3°18′39″W	20 February 2003	Bridge A single high-arch bridge over the River Taff similar in design to the nearby Greenfield bridge. Built in 1815 to replace a wooden bridge of 1800–02 it was originally as part of the Merthyr Tramway but is now a footbridge. It is part of the Merthyr Tramroad scheduled monument.

NOTE
The two viaducts constructed as part of the Brecon and Merthyr Railway both straddle the borders of neighbouring historic communities so have separate designations for each of these locations.

Watkin George

Today marks the 200th anniversary of the death of one Merthyr’s greatest pioneers – Watkin George.

Watkin George is not a name that most people think of when talking about Merthyr’s great men of the past, but his contribution to the town’s history and his legacy is incalculable.

Born in about 1759 in Trevethin, Pontypool, very little is known about his early life, other than he trained as a carpenter, but by his early thirties, he had had married Anne Jenkins (of also of Trevethin), and had moved to Merthyr to work at the Cyfarthfa Ironworks as an engineer, as his expertise in designing and building metal structures had become well known.

He soon became the foundry manager at the Cyfarthfa Works, and in 1792, Richard Crawshay appointed him as a partner in the business. One of his first projects as partner was designing the Pont-y-Cafnau (Bridge of Troughs), a combined tramroad and enclosed aqueduct built to supply the works with limestone and water.

The Gwynne Aqueduct leading to the Pont-y-Cafnau (middle right) from a painting by Penry Williams

Pont y Cafnau Aqueduct, rendered still in a south-east isometric view, taken from the 3D Studio Max model. © Crown copyright: RCAHMW. This image is Crown copyright and is reproduced with the permission of the Royal Commission on the Ancient and Historical Monuments of Wales (RCAHMW), under delegated authority from The Keeper of Public Records.

This was closely followed by the incredible and innovative design for a mechanism to pump air into the blast furnaces – a huge timber aqueduct spanning the River Taff and providing water to power a 15m diameter waterwheel, used to work an air pump for blowing the iron smelting furnaces. The Gwynne Aqueduct and ‘Aeolus Waterwheel’ soon became famous throughout the country, and visitors would come to Merthyr just to see them. Indeed Some contemporary accounts actually referred to the Aeolus Wheel as ‘the Eighth Wonder of the World’.

‘Cyfarthfa Works and Waterwheel’ by William Pamplin. The Aeolus Waterwheel can clearly be seen at the centre of the illustration. Photo courtesy of Cyfarthfa Castle Museum & Art Gallery

In 1799, George designed what would become his most iconic structure – the Old Iron Bridge, and two years later he designed the Ynysfach Ironworks.

In about 1805, having helped Cyfarthfa Ironworks expand, George left the partnership. Reports vary on the amount of money he amassed for his 13 years of service, either £40,000 or £100,000 — “equal to one share”. He joined Pontypool Ironworks as partner to its owners Capel Hanbury Leigh (1776-1861) and Robert Smith, restructuring the works and making great improvements to balling and refinery operations.

In 1811 he prepared a design for Chepstow Bridge – a series of cast iron spans on the existing piers. His design was not adopted, and the new bridge was eventually designed by John Urpeth Rastrick. George’s designs for the Chepstow bridge are his last known work.

Watkin George died on 10 August 1822 and was buried at St Cadoc’s Church in Trevethin.

Today, of his works, the Ynysfach Ironworks Engine House still stands, and his Pont-y-Cafnau is the oldest surviving example of a cast iron railway (tramway) bridge and aqueduct, and is probably the second oldest surviving iron bridge in the British Isles (after Ironbridge in Shropshire), so he is certainly someone who should be remembered amongst the great men of Merthyr.

Scheduled Monuments in Merthyr

I recently received an enquiry asking whether there were any Scheduled Monuments in Merthyr Tydfil. The following is transcribed from Wikipedia:-

Merthyr Tydfil County Borough has 43 scheduled monuments. The prehistoric scheduled sites include many burial cairns and several defensive enclosures. The Roman period is represented by a Roman Road. The medieval periods include two inscribed stones, several house platforms and two castle sites. Finally the modern period has 14 sites, mainly related to Merthyr’s industries, including coal mining, transportation and iron works. Almost all of Merthyr Tydfil was in the historic county of Glamorgan, with several of the northernmost sites having been in Brecknockshire.

Scheduled monuments have statutory protection. The compilation of the list is undertaken by Cadw Welsh Historic Monuments, which is an executive agency of the National Assembly of Wales. The list of scheduled monuments below is supplied by Cadw with additional material from RCAHMW (Royal Commission on the Ancient and Historical Monuments of Wales) and Glamorgan-Gwent Archaeological Trust.

Name	Site type	Community	Details	Historic County
Gelligaer Standing Stone	Standing stone	Bedlinog	A 2 m (6.6 ft) high stone on open moorland. Probably Bronze Age and with the possible remains of a Bronze Age burial alongside. An inscription on the stone, now mostly illegible, is described as either post-Roman/Early Christian or Early Medieval.	Glamorganshire
Coed Cae Round Cairns	Round cairn	Bedlinog	Located in a cairnfield with at least 19 stony mounds, the scheduling consists of a group of eight Bronze Age burial cairns.	Glamorganshire
Gelligaer Common Round Cairns	Round cairn	Bedlinog	A group of eleven Bronze Age burial cairns.	Glamorganshire
Carn Castell y Meibion ring cairn	Ring cairn	Cyfarthfa Troed-y-rhiw	A ring cairn, possibly dating to the Bronze Age, with a 8 m (26 ft) diameter and surrounded by a 3 m (9.8 ft) wide stony ring bank.	Glamorganshire
Brynbychan Round Cairn	Round cairn	Merthyr Vale,	A Bronze Age circular cairn with a diameter of 18 m (59 ft). There is an OS triangulation pillar on the site.	Glamorganshire
Cefn Merthyr Round Cairns	Cairnfield	Merthyr Vale		Glamorganshire
Morlais Hill ring cairn	Ring cairn	Pant		Glamorganshire
Tir Lan round barrow cemetery	Round barrow	Treharris	The remains of six Bronze Age round barrows, three to the north-west and three to the south-east of Tir Lan farm. All six remain substantially intact despite being reduced by ploughing in the past.	Glamorganshire
Garn Las Earthwork	Round cairn	Troed-y-rhiw	The remains a circular burial cairn measuring 14 m (46 ft) in diameter, probably dating to the Bronze Age.	Glamorganshire
Merthyr Common Round Cairns	Round cairn	Troed-y-rhiw	A group of six Bronze Age burial cairns ranging from 5 to 19 m (16 to 62 ft) in diameter.	Glamorganshire
Carn Ddu platform cairn	Platform Cairn	Vaynor		Glamorganshire
Cefn Cil-Sanws ring cairn	Ring cairn	Vaynor		Glamorganshire
Cefn Cil-Sanws, Cairn on SW side of	Round Cairn	Vaynor		Brecknockshire
Coetgae’r Gwartheg barrow cemetery	Round cairn	Vaynor		Glamorganshire
Garn Pontsticill ring cairn	Ring cairn	Vaynor		Glamorganshire
Dyke 315m E of Tyla-Glas	Ditch	Bedlinog	The remains of a later prehistoric/medieval dyke with a clearly defined bank and ditch running east-west across a ridge top. The 3 m (9.8 ft) wide ditch is 1.5 m (4.9 ft) deep at its east end.	Glamorganshire
Cefn Cil-Sanws Defended Enclosure	Enclosure – Defensive	Vaynor		Brecknockshire
Enclosure East of Nant Cwm Moel	Enclosure – Defensive	Vaynor		Glamorganshire
Enclosure on Coedcae’r Ychain	Enclosure – Defensive	Vaynor		Glamorganshire
Gelligaer Common Roman Road	Road	Bedlinog		Glamorganshire
Nant Crew Inscribed Stone (now in St John’s Church, Cefn Coed )	Standing stone	Vaynor	A 1.5 m (5 ft) high square-sectioned pillar stone thought to date to the Bronze Age. A Latin inscription on the west face and cross incised on the north face are from the 6th and 7th-9th centuries. Holes in the stone indicate that it had been used as a gatepost.	Brecknockshire
Platform Houses and Cairn Cemetery on Dinas Noddfa	House platforms (& Cairnfield)	Bedlinog	Medieval house platforms, also prehistoric cairnfield	Glamorganshire
Platform Houses on Coly Uchaf	Platform house	Bedlinog		Glamorganshire
Morlais Castle	Castle	Pant	The collapsed remains of a castle begun in 1288 by Gilbert de Clare, Lord of Glamorgan. The walls enclosed an area of approximately 130 by 60 m (430 by 200 ft). It was captured during the 1294-95 rebellion of Madog ap Llywelyn and may have been abandoned shortly afterwards.	Glamorganshire
Cae Burdydd Castle	Motte	Vaynor	A 3 m (9.8 ft) high motte and ditch dating to the medieval period. The diameter of 23 m (75 ft) narrows to 9 m (30 ft) at the top.	Brecknockshire
Cefn Car settlement	Building (Unclassified)	Vaynor		Glamorganshire
Gurnos Quarry Tramroad & Leat	Industrial monument	Gurnos		Glamorganshire
Sarn Howell Pond and Watercourses	Pond	Town		Glamorganshire
Abercanaid egg-ended boiler	Egg-ended Boiler, re-purposed as garden shed	Troed-y-rhiw		Glamorganshire
Cyfarthfa Canal Level	Canal Level	Cyfarthfa		Glamorganshire
Cyfarthfa Tramroad Section at Heolgerrig	Tramroad	Cyfarthfa		Glamorganshire
Iron Ore Scours and Patch Workings at Winch Fawr, Merthyr Tydfil	Iron mine	Cyfarthfa		Glamorganshire
Ynys Fach Iron Furnaces	Industrial monument	Cyfarthfa		Glamorganshire
Penydarren Tram Road	Trackway	Merthyr Vale		Glamorganshire
Iron Canal Bridge from Rhydycar	Bridge	Park		Glamorganshire
Pont-y-Cafnau tramroad bridge	Bridge	Park	An ironwork bridge spanning the River Taff constructed in 1793. The name, meaning “bridge of troughs”, comes from its unusual three tier design of a tramroad between two watercourses, one beneath the bridge deck and the other on an upper wooden structure which is no longer present. Pont-y-Cafnau is also Grade II* listed.	Glamorganshire
Merthyr Tramroad: Morlais Castle section	Tramroad	Pant		Glamorganshire
Merthyr Tramroad Tunnel (Trevithick’s Tunnel)	Tramroad	Troed-y-rhiw		Glamorganshire
Cwmdu Air Shaft & Fan	Air Shaft	Cyfarthfa		Glamorganshire
Remains of Blast Furnaces, Cyfarthfa Ironworks	Blast Furnace	Park		Glamorganshire
Tai Mawr Leat for Cyfarthfa Iron Works	Leat	Park		Glamorganshire
Deserted Iron Mining Village, Ffos-y-fran	Industrial monument	Troed-y-rhiw		Glamorganshire

Please follow the link below to see the original:-

https://en.wikipedia.org/wiki/List_of_scheduled_monuments_in_Merthyr_Tydfil_County_Borough

Notes on the Merthyr Tydfil Tramroads – part 2

by Gwilym and John Griffiths

Cwm Cannaid Tramroad: We do not know when this tramroad was constructed. We would guess it was sometime around 1800-1814. Despite its name, the tramroad was built before the shaft of Cwm Cannaid Colliery was sunk. The track was shown clearly on the 1814 Ordnance Survey Map and on Robert Dawson’s 1832 Boundary Commission Map whereas the shafts of Cwm Cannaid Colliery were apparently sunk about 1845. The purpose of the tramroad was to relieve the inefficient old tub canal, or coal canal, sometimes called the Cyfarthfa Coal Canal, of the 1770s. The latter transported coal (and perhaps ironstone?) in two-ton tubs from levels (some suggested via dangerous leats) in Cwm Cannaid to Cyfarthfa Works: some say horse-drawn, others say hauled or pushed by men and women. The Cyfarthfa Coal Canal was closed around 1835, which gives an explanation of Cwm Cannaid Tramroad on Robert Dawson’s 1832 Boundary Commission Map.

The tramroad followed roughly the route of the old coal canal: the latter a twisting route, the former almost a straight line. It skirted Glyn Dyrys Ironstone Mine, a coal shaft below Lower Colliers Row, in front of Lower Colliers Row itself, Tir Wern Uchaf (where it crossed the canal twice), a link to Cwm y Glo Colliery and Ironstone Mine, Upper Colliers Row, Tir Heol Gerrig and hence to the coke ovens and yards above (to the west) of Cyfarthfa Works.

Lower Colliers Row. Photo courtesy of the Alan George Archive

When Cwm Cannaid Pit was sunk in 1845, that became the terminus of the system. The 1901 Ordnance Survey Map named it ‘Cwm Pit Railway’, and the line linking it to ‘Gethin Railway’ was labelled ‘railway in course of construction’. We saw the remnants of these mines, canal and tramroad in the 1940s and 1950s, and often walked the old canal embankment, by then well wooded.

A section of the 1901 Ordnance Survey Map showing the tramroad marked as ‘Cwm Pit Railway’. Lower Colliers Row and the old Cyfarthfa Canal are also shown.

Again, industrial despoliation was reverting to nature: delicious wild strawberries on the old waste tipping, a nightingale singing by the disused and reed-covered canal reservoir, woodcock and common snipe, pied flycatchers and wood warblers, and numerous other birds; with wild orchids amongst the damp marshy vegetation with dragon-flies, damsel-flies, glow-worms and water-boatmen. We doubt if this still exists in the coniferous plantations which replaced them all in more recent years.

Dowlais Tramroad: This was constructed about 1792-93 to connect Dowlais Works with Pont y Storehouse near the Glamorgan Canal terminus, roughly near present-day Jackson’s Bridge. It gave Dowlais Works access to the then ‘recently’ constructed Glamorgan Canal. The route may well have followed initially the Morlais Quarry Tramroad from Dowlais via Gelli Faelog, keeping to the Gelli Faelog side of Nant Morlais. The 1793 extension from this tramroad is today represented by the main road and high pavement from Trevithick Street down to Pont Morlais and thence via the tunnel, formerly a bridge, into Bethesda Street to Jackson’s Bridge. Did the Glamorgan Canal Company pay the £1,100 for the construction of the tramroad (and Jackson’s Bridge) in lieu of the proposed linking canal from Merthyr Tudful to Dowlais?

Bethesda Street in the 1950s. The car is parked on what was the where tramway exited the tunnel mentioned above and continued to the Glamorganshire Canal at Pontstorehouse. Photo courtesy of the Alan George Archive

Gethin Tramroad: This tramroad or railway linked Gethin Colliery (sunk between 1845 and 1849 and opened 1849) initially, and Castle Colliery later (1860s?), with Cyfarthfa Works, taking a route in between those of Cwm Cannaid Tramroad and Ynys Fach Tramroad. No tramroad was shown on the 1850 Tithe Map and Schedule. By 1886 the track left Castle Colliery, skirted the hillside west of the Glamorgan Canal between Furnace Row and Tir Pen Rhiw’r Onnen, through Gethin Colliery (with a link to pit-shaft No2), past Graig Cottage and a bridge over Nant Cannaid. At (the 1853) Cyfarthfa Crossing it curved northwestwards past Tir Wern Isaf and Tir Llwyn Celyn, looping under the 1868 Brecon and Merthyr Railway near Heol Gerrig, and thence to the coke yards.

Gethin Colliery. Photo courtesy of the Alan George Archive.

By 1886 the route was upgraded to the GWR and Rhymney Railway as far as the Cyfarthfa Crossing. The 1876 six-inch Ordnance Survey Map showed the terminus for the ‘cwbs’ at the rear of Cyfarthfa Works. The 1901 Ordnance Survey Map called it ‘Gethin Railway’. Our grandfather used the railway to get to work at Castle Colliery, and we regularly used this route (then upgraded to a full railway) in the 1940s and 1950s on our daily journeys to and from school at Quakers Yard. One of us was on the last train to use this line before the viaduct between Quakers yard and Pont y Gwaith was found to be unsafe.

Gyrnos Quarry Tramroad: This was used to bring limestone from Gyrnos Quarry (Graig y Gyrnos) alongside Tâf Fechan, past the limekilns and coal yards, over Afon Tâf by Pont Cafnau to Cyfarthfa Works. We have no details of dates, but walked the route many times in the 1950s in search of dippers, kingfishers, grey wagtails and the rest. It was the first tramroad recorded in the 1805 list of John Jones and William Llywelyn: 1 mile 106 yards to Cyfarthfa Furnaces and just over 1¾ miles to the new Ynys Fach Furnaces. In view of the size of the quarry, it must have transported many tons of material.

The Aeolus Waterwheel – Merthyr’s Great Wonder

When Rev Sir Thomas Cullum (8th Baronet Cullum) visited Merthyr Tydfil in 1811, one of the sights he was most taken with was the mighty Aeolus Waterwheel at the Cyfarthfa Ironworks, and he even called it ‘the wonder of the place’. Some contemporary accounts actually refer to it as ‘the Eighth Wonder of the World‘. I wonder how many people in Merthyr have actually heard of it nowadays?

When Richard Crawshay became sole owner of the Cyfarthfa Works in 1791, he began making plans to extend the works and come up with innovative ways to increase iron production. In 1792, he made the engineer Watkin George a partner in the firm, and the latter began making significant progress in maximising the potential of the works.

His major contribution was the construction between 1793 and 1797 of a huge overshot waterwheel to provide the air for the four blast furnaces.

According to volume 5 of Rees’s Manufacturing Industry (1819-20):

“…..the water-wheel is 50 feet in diameter and six feet wide: it is chiefly made of cast iron, and has 156 buckets. The axle is a hollow tube, and is strengthened by twenty-four pieces of timber applied around it. On each end of the axis is a cog-wheel of twenty-three feet diameter, which turns a pinion. On the axis of these are two cranks, and fly-wheel twenty-two feet diameter, and twelve tons weight; each of the cranks gives motion to a lever, like that of a large steam-engine, and works the piston of a blowing cylinder or air-pump 52½ inches in diameter, and five feet stroke, which blows air into the furnace, both when the piston goes up and down. The work on the other side being the same, it actuates in the whole four of these double cylinders; the wheel makes about two and a half turns per minute, and each cylinder makes ten strokes.”

At the time, it was the largest waterwheel of its kind in the world and was named Aeolus after a character in Greek Mythology. Aeolus, as mentioned in the Odyssey and the Aeneid, was the keeper of the winds and king of the island of Aeolia, one of the abrupt rocky Lipara islands close to Sicily. Later classical writers regarded him as a god.

The wheel was operated by water fed from streams across the river and transported by a massive iron and wood double aqueduct mounted on stone piers between 60 and 70 feet high. This was the famous Gwynne Aqueduct. Sir Charles Manby (later Secretary of the Institution of Civil Engineers) visited Merthyr and commented that the aqueduct:

“…..maintained an apparent lightness of the whole that contrasted with the massy [sic] boundary of the river, has not only a singular, but also a very interesting and pleasing appearance.”

Gwynne Aqueduct from a painting by Penry Williams

This is the same aqueduct that was mentioned in the previous post about the Pont-y-cafnau (http://www.merthyr-history.com/?p=678)

The Aeolus Waterwheel continued to power the blast furnaces until the 1820’s when it was replaced by a steam powered engine, and was subsequently demolished.

Merthyr’s Bridges: Pont-y-Cafnau

The Grade II* listed Pont-y-Cafnau over the River Taff in Cyfarthfa is thought to be the world’s oldest iron tramroad bridge. An influential early prototype and is a unique survivor of its kind, it is also an aqueduct, with a water trough below the deck. Its designer was Watkin George (c.1759-1822), the chief engineer of the nearby Cyfarthfa Ironworks, which it served, and the bridge/aqueduct enabled the movement of limestone on its tram rails and a water supply, both for the ironworks. The limestone came from the Gurnos Quarries, and the water from a leat supplied by the Taf Fechan. The water was used to drive waterwheels to generate power to run machinery for iron smelting.

The structure was designed sometime in 1792 and construction began in January 1793 and the bridge was completed some time before 1796.

The distinctive appearance of the bridge is created by two large cast iron A-frames, which span the river, their raking ends embedded in the coursed rubble abutment walls on either side. The span measures 14.3m. Three transverse iron beams, at the halfway and quarter-points, connect the A-frames and support the deck. George was originally a carpenter and he used carpentry techniques for the ironwork – mortise-and-tenon and dovetail joints can be seen.

The deck consists of rectangular aqueduct trough, 1.9m wide and 610mm high, made of long iron plates. The trough is covered by an iron deck, cast in sections, on which was laid the 1.22m (4ft) gauge tramroad. Wagons ran on straight iron rails carried on iron chairs. Some chairs and sleepers are still in place along the full length and segments of rail survive at the southern end.

The cast iron handrails were supported at the centre and quarter points of the span. Most of the original cast iron railings have now been replaced.

In 1795, a second bridge was cast from the same patterns to carry an extension of the tramroad and aqueduct from the ironworks to the Glamorganshire Canal. This bridge, sadly, no longer exists.

Shortly after Pont-y-Cafnau was completed, the Gwynne Water Aqueduct (completed 1796) was constructed over the top of it. Gwynne Water was 185m long, built entirely of timber and used the cast iron uprights of the bridge for support. it supplied water to the 15m diameter Aeolus waterwheel, also designed by George, which powered an air pump for the blast furnaces. Presumably, the extra bracing that has been added to the bridge dates from this work. Nothing of the second aqueduct remains.

Pont-y-Cafnau is a Scheduled Ancient Monument as well as a Grade II* listed structure. The iron trough no longer carries water. However, its name means “bridge of troughs”, testifying to its former life.

The bridge influenced the construction of other, better known, aqueducts. In 1794, Shropshire ironmaster William Reynolds (1758-1803) made a sketch of it. Reynolds’ involvement in the rebuilding of Thomas Telford’s (1757-1834) navigable Longdon on Tern Aqueduct on the Shrewsbury Canal in 1796 seems to have led Telford to reconsider using stone and to opt instead for cast iron. It was also the prototype for Telford’s famous Pontcysyllte Aqueduct, which opened in 1805.