But the value of a silver mine, even though there should not be another within a thousand miles of it, will not necessarily increase with the improvement of the country in which it is situated. The market for the produce of a freestone quarry can seldom extend more than a few miles round about it, and the demand must generally be in proportion to the improvement and population of that small district. But the market for the produce of a silver mine may extend over the whole known world. Unless the world in general, therefore, be advancing in improvement and population, the demand for silver might not be at all increased by the improvement even of a large country in the neighbourhood of the mine. Even though the world in general were improving, yet if, in the course of its improvement, new mines should be discovered, much more fertile than any which had been