successful working of a new mine can alone ascertain the reality of its value, or even of its existence. In this search there seem to be no certain limits either to the possible success or to the possible disappointment of human industry. In the course of a century or two, it is possible that new mines may be discovered more fertile than any that have ever yet been known; and it is just equally possible the most fertile mine then known may be more barren than any that was wrought before the discovery of the mines of America.

Whether the one or the other of those two events may happen to take place is of very little importance to the real wealth and prosperity of the world, to the real value of the annual produce of the land and labour of mankind. Its nominal value, the quantity of gold and silver by which this annual