234 Mining System. 



produce an intense ignition of the charcoal, contained in them, and 

 to increase the effect, the furnaces were placed upon the summits of 

 the hills, where, of course, the wind was most powerful. The result 

 of this operation, was an argentiferous matt, which was rernelted in 

 similar furnaces in the Indian cabins, the blast being supplied by ten 

 or twelve men with long copper tubes, having small orifices. This 

 method was followed up by the Spaniards in the Peruvian mines, 

 until 1571, when the Mexican method of amalgamation was adopted 

 at Potosi. 



Mining system. 



The exploration of the Mexican mines, up to the time, when 

 Humboldt examined them, was very defective, although mining had 

 been, for more ihan three hundred years, a constant source of em- 

 ployment to many of the inhabitants. The only improvement that 

 had been introduced, was that of blasting with gunpowder. 



Some of the defects of the system of mining employed in Mexico are, 



1st. They have no plan of the works, so that two galleries may 

 be very near each other, without their knowing it ; they have no sure 

 rule, either for forming a communication, or for directing the excava- 

 tion of new galleries, upon a point found to be very rich. Two 

 hundred and fifty miners perished in 1780, at Guanaxuato, because 

 they had, without knowing it, imprudently advanced near some old 

 inundated excavations, from which they thought themselves at a con- 

 siderable distance. 



2d. In most mines, the communications between the different parts 

 are circuitous. This is one of the great faults of their explorations, 

 which are, in this respect, like a badly constructed edifice, in which, to 

 pass from one room to an adjoining one, you must travel through the 

 whole house. Some of the mines, consisting of several small works, 

 each of which has only one opening, without any lateral communica- 

 tions, are still more defective. 



3d. The shafts and galleries are much too large. There are gal- 

 leries of research, from twenty-five to thirty feet in height ! The 

 miners were under the impression, that the great height facilitated 

 the ventilation. They also entertained the prejudice, that the galle- 

 ries should be broad, instead of cutting transverse ones at short dis- 

 tances between the others, or towards the walls of the vein. The 

 galleries, when large, are so expensive, that they cannot multiply 

 them, as much as the ventilation of the mine demands. 



