The comparative quantities of these, at the different mines, is very variable, and few of the miners are able to determine them with exactness. Notwithstanding the antiquity of the silver mining business in Mexico, the processes which are employed are still far from perfect, and greatly behind those of the Nevada and other mines. The ore in Mexico is so rich that it has not been considered worth while to practice any economy or to bring science to the miner’s aid. Col. Albert S. Evans, who made a journey through Mexico, a few years ago, gives a graphic account of a visit to the Serrano mine, in the vicinity of Guanajuato. He was invited, with several others, to a pyrotechnic display in the mine, and thus describes it: [Sidenote: THE SERRANO MINE.] “The mine is situated in the hill below the Buffa, at the upper end of the city. Five hundred men, women, and children are employed at this mine, getting out the ore, breaking it up, and sorting it. The men generally work in small gangs, for a share of the sales of the ore they take out. The amount of silver mined, weekly, is about five thousand dollars, and the expenses one thousand dollars, leaving a net profit of four thousand dollars. The great tiro is about nine hundred and fifty feet in depth. A horizontal tunnel penetrates the hill from a level with the hacienda, cutting the tiro, or perpendicular shaft, at four hundred feet from the surface. This tunnel may be about fifteen hundred feet in length; a railroad track runs through it, and lying down in the cars, we were carried in to the edge of the tiro. This tiro is thirty feet in diameter, and six sided, laid up in cement, like that at the Valenciano. The necessity for this is seen in the fact that a rock, weighing many tons, was displaced from a station near the bottom of the shaft, a few days previous to our visit, and falling upon the miners beneath, killed and maimed a large number of them. Standing here, four hundred feet below the surface of the earth, and six hundred feet above the bottom of the shaft, with a patch of pale blue sky far above us, and inky darkness, almost palpable to the touch, around us, and filling all the depths below, we witnessed the most wonderful scene on which we gazed in Mexico. Men were sent up to the top of the tiro at the surface of the ground, and told to discharge rockets down it. This they did, and the hissing and explosions of the fiery messengers caused the most deafening echoes and re-echoes, while the sides of the shaft, dripping with ooze and slime, were revealed with startling distinctness by the momentary glare.