be a third of the gross produce; and it is generally a rent certain and independent of the occasional variations in the crop. In coal mines a fifth of the gross produce is a very great rent; a tenth the common rent, and it is seldom a rent certain, but depends upon the occasional variations in the produce. These are so great, that in a country where thirty years' purchase is considered as a moderate price for the property of a landed estate, ten years' purchase is regarded as a good price for that of a coal mine.
The value of a coal mine to the proprietor frequently depends as much upon its situation as upon its fertility. That of a metallic mine depends more upon its fertility, and less upon its situation. The coarse, and still more the precious metals, when separated from the ore, are so valuable that they can generally bear the expense of a very long land, and of the most distant sea carriage. Their market is not confined to the countries in the neighborhood of the mine, but extends to the whole world. The copper of Japan makes an article of commerce in Europe; the iron of Spain in that of Chile and Peru. The silver of Peru finds its way, not only to Europe, but from Europe to China.
The price of coals in Westmoreland or Shropshire can have little effect on their price at Newcastle; and their price in the Lionnois can have none at all. The productions of such distant coal mines can never be brought into competition with one another. But the productions of the most distant metallic mines frequently may, and in fact commonly are. The price, therefore, of the coarse, and still more that of the precious metals, at the most fertile mines in the world, must necessarily more or less affect their price at every other in it. The price of copper in Japan must
