Valenciana*, executed with the viewof making trial on a poor vein, of a height of 26 or 29 feet. It is an erroneous opinion, that this great height facilitates the renovation of the air; the ventilation depends on the equilibrium and difference of temperature between two neighbouring columns of air. They believe also, equally without foundation, that, in order to discover the nature of a powerful vein, very large drifts are requisite, as if, in mineral veins of from six to eight fathoms in width, it were not better to cut from time to time small cross drifts, for the purpose of discovering whether the mass of the vein begins to grow richer. The absurd custom of cutting every level of such enormous dimensions, prevents the proprietors from multiplying the means of trial, so indispensable for the preservation of a mine and the duration of the works. At Guanaxuato, the breadth of the oblique shafts dug stairwise is from five to six fathoms; and the perpendicular shafts are generally three, four, or five fathoms in diameter. The enormous quantity of ores extracted from the mines, and the necessity of working in them the ropes attached to six or eight whims, necessarily occasion the shafts of Mexico to be made of greater dimensions than those of Germany; but the attempt which has been made at Bolaños to separate by beams the ropes of the whims, has sufficiently proved that the breadth of the shafts may be

* Canon de la Soledad.

STATE OF THE ART OF MINING.

191

diminished without any danger of the ropes entangling in their oscillatory motion. It would in general be very useful to make use of kibbles instead of leathern bags suspended by ropes for the extraction of the ores.

The greatest fault observable in the mines of New Spain, and which renders the working of them extremely expensive, is the want of communication between the different works. They resemble illconstructed buildings, where, to pass from one adjoining room to another, we must go round the whole house. The mine of Valenciana is justly admired on account of its wealth, the magnificence of its walling, and the facility with which it is entered by spacious and commodious stairs; yet it exhibits only a union of small works irregularly conducted; they are as it were cul de sacs, and without any lateral communication. I mention this mine, not because it is more faulty than the others in the distribution of its labours, but because we might naturally suppose it to be better organized. As subterraneous geometry had been entirely neglected in Mexico, till the establishment of the School of Mines, there is no plan inexistence of the works already executed. Two works in that labyrinth of cross levels and interior winzes, may happen to be very near each other, without its being possible to perceive it. Hence the impossibility of introducing, in the actual state of most of the mines of Mexico, the wheeling by means of barrows, and an economical disposition of the

ore plats. A miner brought up in the mines of Freiberg, and accustomed to see so many ingenious means of conveyance practised, can hardly conceive that in the Spanish colonies, where the ores are poor though very abundant, all the metal which is taken from the vein is carried on the backs of men. The Indian tenateros, who may be considered as the beasts of burden of the mines of Mexico, remain loaded with a weight of from 250 to 380 pounds for a space of six hours. In the levels of Valenciana and Rayas, they are exposed, as we have already observed in speaking of the health of the miners, to a temperature of from 71° to 77° Fahr. ; and during this time they ascend and descend several thousands of steps in shafts of an inclination of 45°. These tenateros carry the minerals in bags (costales) made of the thread of the pité. To prevent their shoulders from being hurt, (for the miners are generally naked to the middle) they place a woollen covering (frisida) under this bag. We met in the mines files of fifty or sixty of these porters, among whom there are men above sixty, and boys of ten or twelve years of age. In ascending the stairs they throw the body forwards, and rest on a staff, which is generally not more than a foot in length. They walk in a zigzag direction, because they have found from long exerience, as they affirm, that their respiration is less impeded when they traverse obliquely the current of air which enters the pit from without.

We cannot sufficiently admire the muscular

strength of the Indian and Mestizo tenateros of Guanaxuato, especially when we ourselves are oppressed with fatigue in ascending from the bottom of the mine of Valenciana, without carrying the smallest weight. The tenateros cost the proprietors of Valenciana more than 6207. weekly; and they reckon that there are three men destined to carry the ores to the depositaries to one workman (barenador) who blows up the vein by means of powder. These enormous expenses of transportation would perhaps be diminished exceedingly, if the works communicated with each other by winzes, or by levels adapted for conveyance by wheel-barrows or rail-roads, Well contrived operations would facilitate the extraction of minerals and the circulation of air, and would render unnecessary this great number of tenateros, whose strength might be employed in a manner more advantageous to society, and less hurtful to the health of the individual. Winzés communicating from one gallery to another, and serving for the extraction of ores, might be provided with windlasses to be wrought by men, or whims to be moved by cattle. For a long time (and this arrangement undoubtedly deserves the attention of the European miner) mules have been employed in the interior of the mines of Mexico. At Rayas these animals descend every morning without guides and in the dark, the steps of a shaft of an inclination of from 42° to 46°. The mules distribute them, selves of their own accord in the different places

where the machines for drawing water are fixed, and their step is so sure, that a lame miner was accustomed several years ago, to enter and leave the mine on one of their backs. In the district of the mines of Peregrino, at the Rosa de Castilla, the mules sleep in subterraneous stables, like the horses which I saw in the famous rock salt mines of Wieliczka in Gallicia.

The smelting and amalgamation works of Guanaxuato and Real del Monte are so placed, that two navigable levels, with their openings near Marfil and Omitlan, might serve for the carriage of ores, and render every sort of draught above this level superfluous. Besides, the descents from Valenciana to Guanaxuato, and from Real del Monte to Regla, are so rapid, that they would admit of the construction of rail-ways, on which waggons loaded with the ores destined for amalgamation might be easily rolled along.

We have already spoken of the truly barbarous custom of drawing off the water from the deepest mines, not by means of pump apparatus, but by means of bags attached to ropes which roll on the cage of a whim. The same bags are used in drawing up the water and the ores: they rub against the walls of the shafts, and it is very expensive to keep them in repair. At the Real del Monte, for example, these bags only last seven or eight days; and they commonly cost five, and sometimes seven and eight shillings a piece. A bag full of water, sus