This rise in the value of silver, in proportion to that of corn, may either have been owing altogether to the increase of the demand for that metal, in consequence of increasing improvement and cultivation, the supply, in the mean time, continuing the same as before; or, the demand continuing the same as before, it may have been owing altogether to the gradual diminution of the supply: the greater part of the mines which were then known in the world being much exhausted, and, consequently, the expense of working them much increased; or it may have been owing partly to the one, and partly to the other of those two circumstances.