Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 132,777 pages of information and 210,006 images on early companies, their products and the people who designed and built them.
Watkin (Watkyn) George (1759-1822)
From Family Search - Community Trees 
Note: The dates in the source are given as 'Calculated'.
Born 1759 at Trefddyn, Monmouthshire, Wales
Died 10th August 1822 at Trefddyn
Married Anne, also of Trefddyn, born 1760.
Two children: Anne born 1794, of, Trefddyn, and Watkin, born 1795.
Tomb at Trefddyn churchyard, south side.
Became famous as the engineer at Cyfarthfa Ironworks.
c.1805 left Cyfarthfa to join Hanbury Leigh at the Pontypool Ironworks.
The Great Water-Powered Blowing Engine at Cyfarthfa
'A Very Large Overshot Wheel. - The largest overshot water-wheel of which we have heard, is that at Mr Crawshaw’s [sic] iron-works at Cyfarthfa, near Merthyr Tidvil, in South Wales : it is used to blow air into three of the large furnaces for smelting iron ; 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. It is called Aeolus, and was built in 1800 under the direction of Mr. Watkin George.' 
In fact the machine was built earlier than the date given by Abraham Rees, probably 1793, when the remarkable aqueduct was built to feed the wheel. The waterwheel was briefly referred to in the Bibliotheque Britannique in 1798 . Another source takes the date back to 1797: 'There has lately been erected at the Ironworks of Mr. Crawshay, Cyfarthva ; near Merthir Tydvil, Glamorganshire, a stupendous Water-wheel, 50 feet in diameter. It is said to be the largest that ever was in motion. This wheel works three pistons which blow four furnaces, and are intended to blow several fineries. This wonderful machine was invented and constructed by Mr. Watkin George, one of the first mechanics that this nation can boast.'
'The most remarkable piece of mechanism in Merthyr Tydvil is the great water wheel made by Watkin George. Its diameter is fifty feet, and it has the power of fifty horses. It has the advantage of water from above, or on its centre, or beneath it ; or, in other words, it possesses all the forces of an overshot, breast, and undershot wheel. I apprehend it to be the largest in the kingdom. Watkin George and William Aubrey, were the two principal engineers, and they are both natives of this country. Watkin George in particular, who planned and executed this immense undertaking, was a common village carpenter. Owing to his success in these mechanical inventions, he got forward by degrees, and became at last so useful to Mr Crawshay, as to obtain a share in his works. He has lately quitted the concern with from thirty to forty thousand pounds in his pocket. This is one among the most remarkable instances of wealth acquired by the untutored ingenuity of the natural faculties.'
Melingriffith Water Pump
The preserved Melingriffith Water Pump was almost certainly designed by Watkin George.
A remarkable surviving example of Watkin George's work is an iron bridge (Pont-y-Cafnau or Pontycafnau) at Cyfarthfa. This is provisionally dated to 1792 - 93, and was a combined tramroad bridge and aqueduct.. It is the oldest surviving example of a cast iron railway (tramway) bridge and aqueduct. Originally another aqueduct was superimposed on this bridge, feeding the large waterwheel.
Ynysgau Iron Bridge
The cast iron Ynysgau Iron Bridge was built in Merthyr in 1799-1800. It was designed by Watkin George and funded by William Crawshay to allow access across the River Taff to Cyfarthfa Iron Works. It was a bold design, and, with repairs, lasted until 1963, when it was brutally dismantled.