Page:Mexico (1829) Volumes 1 and 2.djvu/469

 MEXICO. 429 of La Borda, upon which some of the most promising mines of the Company are situated ; and, in both instances, a depth of 132 yards below the deepest of the old workings will be obtained. The Gallery is two yards wide, and three and a half high, being constructed in such a manner as to allow of the use of small carts. In order to facilitate its construction, twelve lumbreras, (air-shafts, (puits cTairage,) have been opened, at intervals of from 350 to 450 yards from each other ; and from each of these, again, two galleries extend to the right and left upon the line of the adit, so as to admit of the greatest possible number of workmen being employed at the same time. The depth of the twelfth of these air-shafts, which is the deepest, is 300 yards : the first is only sixty-three yards deep ; but the aggregate depth of all amounts to 2,332 yards. It is in this that the great expense of the undertaking consists, as well as its difficulty. The aggregate depth of the air-shafts constructed for the Tunnel at Bolanos, is only 180 yards ; and the tunnel itself, being merely a water course, is upon a much smaller scale than the Tlalpujahua adit, (four feet deep, by six wide.) There can be no doubt, hoAvever, that both Mr. Burkart, and Mr. Moro, are perfectly competent to carry through the undertaking in which they have engaged, provided they are supported by the Shareholders at home ; and every one at all acquainted with mining must perceive the advantages which would result from it to the Adventurers, as, in all their prin- cipal mines, it would ensure both the drainage, and the ex- traction of Ores, for the space of 132 yards of virgin ground, without the expense of machinery above ; which requires not only a permanent investment of capital, but frequent additions, for repairs, as well as for keeping up the supply of animals, by which it must be worked. In the Autumn of 1826, fifty yards of the great Gallery had been driven, (from the mouth,) and the air-shafts, Nos. 1, 2, 3, 10, 11, and 12, commenced. Some of these had