The processes described by Cort in his two patents have been followed by iron manufacturers, with various modifications, the results of enlarged experience, down to the present time. After the lapse of seventy-eight years, the language employed by Cort continues on the whole a faithful description of the processes still practised: the same methods of manufacturing bar from cast-iron, and of puddling, piling, welding, and working the bar-iron through grooved rollers--all are nearly identical with the methods of manufacture perfected by Henry Cort in 1784. It may be mentioned that the development of the powers of the steam-engine by Watt had an extraordinary effect upon the production of iron. It created a largely increased demand for the article for the purposes of the shafting and machinery which it was employed to drive; while at the same time it cleared pits of water which before were unworkable, and by being extensively applied to the blowing of iron-furnaces and the working of the rolling-mills, it thus gave a still further impetus to the manufacture of the metal. It would be beside our purpose to enter into any statistical detail on the subject; but it will be sufficient to state that the production of iron, which in the early part of last century amounted to little more than 12,000 tons, about the middle of the century to about 18,000 tons, and at the time of Cort's inventions to about 90,000 tons, was found, in 1820, to have increased to 400,000 tons; and now the total quantity produced is upwards of four millions of tons of pig-iron every year, or more than the entire production of all other European countries. There is little reason to doubt that this extraordinary development of the iron manufacture has been in a great measure due to the inventions of Henry Cort. It is said that at the present time there are not fewer than 8200 of Cort's furnaces in operation in Great Britain alone.[5] Practical men have regarded Cort's improvement of the process of rolling the iron as the most valuable of his inventions. A competent authority has spoken of Cort's grooved rollers as of "high philosophical interest, being scarcely less than the discovery of a new mechanical Power, in reversing the action of the wedge, by the application of force to four surfaces, so as to elongate a mass, instead of applying force to a mass to divide the four surfaces." One of the best authorities in the iron trade of last century, Mr. Alexander Raby of Llanelly, like many others, was at first entirely sceptical as to the value of Cort's invention; but he had no sooner witnessed the process than with manly candour he avowed his entire conversion to his views.