But we are of opinion, that the manufacture of iron by charcoal is not that to which our country should look for its final supply. It is at best a precarious resource, and its production must diminish with the advance of agriculture, and the consequent demand, while every increase in the price of land must raise the cost. It is then to a total change in the seat and mode of manufacture, that we are to be hereafter beholden for the supply of this first necessary of civilized life. A change will first take place in the sites of the two branches; pig iron will continue to be manufactured by charcoal, and the bar converted by coal. For this the great coal field of Pennsylvania will afford the earliest facilities. No doubt can be entertained that the more freely burning varieties of anthracite will work well in the puddling furnace, as they have been successfully employed in the rolling and slitting of bar iron. When the same species of coal is mixed with charcoal in the blast furnace, it produces excellent forge pig, and thus the two species of fuel may be advantageously united, although the coal alone will not answer the purpose. The value of this coal in the mine and the cost of raising it, is as yet less than that of bituminous coal in any part of Europe, and thus we cannot avoid concluding that when it shall be brought into use, our manufacturers might compete with the English even if unprotected by duty. Our fields of bituminous coal are yet too distant from dense population, and too far removed from easy communication, to be looked to at present, but unless modes be invented by which the anthracite coal can be used without mixture in the blast furnace, these will become the ultimate seats of the manufacturing industry of the United States.