Such is the case with a multitude of other mines which have formed the _nucleii_ of population in Mexico. They created a market. The men who were at work in the vein, required the labor of men on the surface, for their support and maintenance. Nor was it food alone, that these laborers demanded. All kinds of artizans were wanted, and consequently, towns as well as farms grew upon every side. When these mining _dependencies_ are once formed, as Baron Humboldt justly says, they often survive the mines that gave them birth; and turn to agricultural labors for the supply of other districts that industry which was formerly devoted solely to their own region. Such are some of the internal advantages to be derived from mining in Mexico, especially when the mines are well and scientifically wrought, and when the miners are kept in proper order, well paid, and consequently enabled to purchase the best supplies in the neighboring markets. The mines are, in fact, to Mexico, what the manufacturing districts are to England and the United States; and they must be considered the great support of the national agricultural interests until Mexico becomes a commercial power, and sends abroad other articles besides silver, cochineal and vainilla,--the two last of which may be regarded as her monopolies. The operation of this tempting character of _mines_ or of the money they create as well as circulate, is exhibited very remarkably in the rapidity with which the shores of California have been covered with towns and filled with industrious population. The tabular statement on the next page manifests the relative production, and improving or decreasing productiveness, of the several silver districts of Mexico, during the comparatively pacific period of ten years antecedent to the war with the United States which commenced in 1846. Whilst that contest lasted the agricultural and mineral interests and industry of the country of course suffered, and, consequently, it would be unfair to calculate the metallic yield of Mexico upon the basis of that epoch or of the years immediately succeeding. From the table it will be seen--omitting the fractions of dollars and of marks of silver--that the whole tax collected during these ten years from 1835 to 1844, amounted to $1,988,799, imposed on 15,911,194 marks of silver, the value of which was $131,267,354;--the mean yield of _tax_ being $198,889, and of the _silver_, 1,591,119, in _marks_, which, estimated at the rate of eight dollars and a quarter, _per_ mark, amounts to $13,126,735 annually. Comparing the first and second periods of five years, we find a difference in the tax in favor of the latter, of $113,130, on 905,042 marks of silver; showing that in the latter period $7,466,596 more were extracted from the Mexican mines than during the former. If we adopt the decimal basis of calculation the returns show, _approximately_, the following results for relative productiveness: