In England, as in other countries, charcoal was the only fuel at first used; and after bloomeries had been in vogue for centuries, the blast furnace was introduced from the shores of the Rhine. For many years the growth of the forests proved sufficient to supply the demand, but at length the increase of population caused them to be encroached upon by cultivation; the growth of the manufacture was first prevented, and finally, almost extinguished. The method by charcoal appears to have reached its acme of prosperity, at the close of the reign of the First James, when the furnaces of the kingdom yielded 180,000 tons of pig iron. About this period, Dudley first proposed the use of pit coal; but the time had not yet arrived in which it was absolutely necessary to seek for a new process, in consequence of the failure of the old one. In 1745, or in the course of one hundred and thirty years, the forests had been so far encroached upon, that the product of the furnaces had fallen to 17,000 tons per annum, and in 1788, the quantity made with charcoal had dwindled as low as 13,000 tons. At this epoch, coke was introduced into blast furnaces, and in eight years the whole quantity produced by both methods had mounted up to 150,000 tons, or increased more than tenfold. At nearly the lowest ebb of the British manufacture, the art of preparing iron was introduced into her then provinces, the present United States; and in 1737 it was attempted to obtain permission to introduce the product into England. The attempt failed, and in 1750 an act was passed to protect the exportation of English iron to America, and to prevent the establishment of forges. Had the other policy prevailed, England would probably have seen her manufacture of iron transferred to the United States, and with great immediate advantage both to herself and her then most valuable colony; but she would probably have seen herself at the present day degraded from her high stand in the scale of nations, to the secondary place in which the extent of her territory would keep her, were it not for the superiority of her manufacturing industry, of which iron is the basis. The quantity of iron now produced in England, exceeds that furnished by the rest of the world united, and does not fall short of 800,000 tons. It has a value even in its raw state of near four millions sterling, and is of far greater intrinsic worth, in consequence of the spur which its abundance gives to every other branch of industry.