The claim is that that is when the Cort process was invented. https://en.wikipedia.org/wiki/Henry_Cort#Rolling_mill_and_puddling_furnace https://en.wikipedia.o

The claim is that that is when the Cort process was invented. https://en.wikipedia.org/wiki/Henry_Cort#Rolling_mill_and_puddling_furnace https://en.wikipedia.org/wiki/Henry_Cort#Rolling_mill_and_pu... Wikipedia also says Cort was born around 1740, so that's a good lower bound even if the 1780s patents came a little late ;)