Henry Cort (c.1741–1800)
In 1784, Henry Cort invented one of the most important iron-making processes of the Industrial Revolution. This was a new method of transforming cast iron into the more versatile and valuable material of wrought iron without labour-intensive hammering. Crucially, his method used coal and worked well for cast iron that was smelted with coked coal, making it possible to have much larger, integrated ironworks.
Cort was born in Lancaster, northern England, in 1740 or 1741. By the age of around 16 he was working as a naval agent – someone who gave out pay for the Royal Navy. A member of his wife’s family owned an iron forge at Gosport on the south coast that supplied ironware to the Royal Dockyard at Portsmouth. Cort invested in the business and took over its management in 1776. He used a mill at the nearby village of Funtley to begin experiments with refining iron. His first patent, in 1783, was for a grooved rolling mill to make bars of iron. His second patent, the next year, was for ‘puddling’. This used a reverberatory furnace to convert pig iron to wrought iron by stirring it and turning it to oxidise the carbon.
The two processes together – puddling and then rolling – were an efficient way to make wrought iron bars and rails. Using coal fuel allowed much larger units of production without the limitations of charcoal supply. The first full application of the process, around 1786, was by Richard Crawshay at Cyfarthfa Ironworks in Merthyr Tydfil, south Wales, which became the largest ironworks in the world. Puddling and rolling became known as ‘the Welsh method’. Production was continuously improved and grew spectacularly so that Britain was the largest iron-producer in the world for more than a generation. By about 1810 the process was used across Europe and America. Puddled wrought iron remained a material for railways, bridges and ornamental ironwork until well after the invention of mass-produced mild steel by Henry Bessemer in 1856.
Just as he was becoming successful, Cort lost everything. It was discovered that money to invest in his invention had come from the Royal Navy; his property and the licenses for his patents were taken away. He was made bankrupt in 1789, with a wife and 13 children to support. His friends helped to get him a pension from the government in 1794 but he died still bankrupt in 1800. Several ironmasters later gave support to his widow.