A replica of the Penydarren Locomotive is back on the rails at the National Waterfront Museum in Swansea
Few things can honestly be said to have changed the course of world history, but Trevithick's steam locomotive must be a contender.
A replica of this extraordinary piece of technology will go through its paces at the National Waterfront Museum in Swansea on Sunday, 13 June.
Cornishman Richard Trevithick built the original for the Penydarren Ironworks in Merthyr Tydfil.
His steam locomotive was the first to make a successful journey on rails.
The replica was assembled from parts made by more than 30 engineering companies in Wales
The locomotive weighs seven tonnes empty and cold
The boiler takes a tonne of water
The boiler shell had to be lagged to reduce excessive fuel consumption
On 21 February 1804 it ran on the nine-mile tramway from Penydarren to Abercynon, hauling a load of ten tonnes of iron and about 70 people who hitched an unofficial ride.
The replica was assembled by technical staff from the Welsh Industrial and Maritime Museum under the guidance of chief engineer, the late Alec Jones.
Iron and brass
It took two years to make from design to completion.
"It's a great opportunity for us to showcase how some of the fantastic collections we have on display were actually used," said Head of Museum, Steph Mastoris.
"It's something the whole family can enjoy and at the same time delve into the history that comes with it."
The original was made mainly of cast iron with some wrought iron and small quantities of brass.
While the replica is made mainly of welded steel, mainly because a cast iron boiler would not be permitted by H.M.Boiler Inspectorate.
Trevithick designed a similar locomotive a year before the Penydarren and another a year after.
So the design of this replica falls between the two locomotives.
The replica locomotive engine was inaugurated in 1981
Key dimensions of the originals were recorded and the museum's plans come from those measurements.
The finished plans, sets of which are regularly sold to model makers, specified every detail and dimension, to enable the engineering companies that made the components to manufacture precisely what was required.
The replica, which is now on display in the museum, has been abroad twice to celebrate the 150th anniversaries of both the Dutch and German state railway systems.
Samuel Homfray bet rival ironmaster Richard Crawshay 500 guineas that the locomotive would pull a train of wagons loaded with 10 tons of iron to the canal basin at Abercynon, and return.
The locomotive succeeded but Crawshay apparently refused to pay because the track had to be moved slightly in one place, and the locomotive needed slight repairs before returning to Merthyr.