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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1811 Excerpt:...work employed in the pits and galleries, and especially the walling with lime, deserves a great deal of praise. The arches are formed with great care, and in this respect the mines of Guanaxuato may stand a comparison with whatever is most perfect at Freiberg and Schemnitz. The pits and still more the galleries of New Spain, have generally the defect of being dug in too great dimensions, 't(artstossh-6he) and of occasioning, by that means, very exorbitant ex Especially in the mines of Valeneiana, Guanaxuato, and the Real del Monte. pences. We find galleries at Valeriana executed with the view of investigating a' sterile vein, of a height of eight or nine metresf. They have taken it into their heads, that this great height facilitates the renovation of the air; but the ventilation solely depends on the equihbrium and difference of temperature between two neighbouring columns of air. They believe also, equally without any foundation, that, in order to discover the nature of a very powerful vein, very large galleries ofinvestiga. tion are requisite, as if in mineral depositories of from twelve to fifteen metres J in extent, it were not better to cut from time to time small cross galleries towards the wall and the roof, f0? the purpose of discovering whether the mass of the vein begins to grow richer. The absurd custom of cutting every gallery in such enormous dimensions, prevents the proprietors from multiplying the labours of investigation, so indispensible for the preservation of a mine, and the length of duration of the works. At Guanaxuato the breadth of the oblique pits dug stairwise, is from ten to 12 metres §; and the perpendicular plts are generally six, eight, or ten metres B broad. The enormous quantity of Canon de la Soledad. t 26 or 29 feet. T...