industrial activity, and a multitude of inventions wholly unrelated to those here cited, received double importance from the fact that they were made in the midst of the universal movement. But as soon as the immeasurable importance of mechanical power was practically demonstrated, every energy was concentrated in the effort to exploit this power in all directions, and to exploit it in the interest of individual inventors and manufacturers; and the demand for machinery, fuel, and materials called a mass of workers and a number of trades into redoubled activity. The steam-engine first gave importance to the broad coal-fields of England; the production of machinery began now for the first time, and with it arose a new interest in the iron mines which supplied raw material for it. The increased consumption of wool stimulated English sheep breeding, and the growing importation of wool, flax, and silk called forth an extension of the British ocean carrying trade. Greatest of all was the growth of production of iron. The rich iron deposits of the English hills had hitherto been little developed; iron had always been smelted by means of charcoal, which became gradually more expensive as agriculture improved and forests were cut away. The beginning of the use of coke in iron smelting had been made in the last century, and in 1780 a new method was invented of converting into available wrought-iron coke-smelted iron, which up to that time had been convertible into cast-iron only. This process, known as "puddling," consists in withdrawing the carbon which had mixed with the iron during the process of smelting, and opened a wholly new field for the production of English iron. Smelting furnaces were built fifty times larger than before, the process of smelting was simplified by the introduction of hot blasts, and iron could thus be produced so cheaply that a multitude of objects which had before been made of stone or wood were now made of iron.