Divers causes appear, however, hitherto to have prevented such a desideratum. In the first place, gold and silver producing countries have generally been in a rude state of civilization; and as unable to apply rules for the public weal, as to employ machinery to aid their industry. Thus, even in the registry in Mexico under the Spanish rule, of all the money coined at their mint, and for ascertaining the amount produced in the mines by the proportion of the tax due to government, which ought to be levied thereon by the hundred-weight,--it is absolutely necessary to take into account all that quantity which escapes the vigilance of the tax-collector, and which is either sent into the interior, or exported clandestinely. What is the sum of the precious metals really produced at any given time? What is the proportion of such production which, when exported, acts as a regulator of the prices in Europe? How are the channels formed which sometimes direct the stream of commerce towards the east, and sometimes towards the west, in the distribution of the metallic wealth of the world? All such problems, as regards the past, must probably remain unsolved. The enquiry becomes more easy when referring to our own times; but even then large allowances for incorrectness of data must necessarily be made. At the beginning of this century, according to M. de Humboldt, gold and silver were imported annually into Europe in the relative proportions of about 1 to 55; that is, [13]15,800 kilogrammes of gold to [14]869,960 kilogrammes of silver. M. Michel Chevalier, stating, not the import but the production, calculates it at [15]23,700 kilogrammes of gold against [16]900,000 kilogrammes of silver, or in the proportion of 1 to 38; but the gold of Africa and Asia, comprised in this statement, never really found its way into European markets except in the smallest quantities, and in such amounts as could have no appreciable influence on the commercial prices of the metals. From 1810 to 1830, according to Mr. Jacob, the produce of America diminished by one half. As the reduction refers principally to silver, that is to say, to those mines which required both capital and labor, it is fair to assume that, at least during the first part of this period, the relative proportion of gold to silver would have increased; but we have no means of verifying figures which appear to justify what would otherwise rest solely on the analogy of the case.