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The fertility or barrenness of the mines, however, which may

happen at any particular time to supply the commercial world, is

a circumstance which, it is evident, may have no sort of

connection with the state of industry in a particular country. It

seems even to have no very necessary connection with that of the

world in general. As arts and commerce, indeed, gradually spread

themselves over a greater and a greater part of the earth, the

search for new mines, being extended over a wider surface, may

have somewhat a better chance for being successful than when

confined within narrower bounds. The discovery of new mines,

however, as the old ones come to be gradually exhausted, is a

matter of the greatest uncertainty, and such as no human skill or

industry can insure. All indications, it is acknowledged, are

doubtful; and the actual discovery and successful working of a

new mine can alone ascertain the reality of its value, or even of

its existence.