History of the big bonanza

by Dan De Quille

Winzes are very often thus made—one set of miners being engaged below at digging up, while above another set are digging down. The progress made by the men below is always much more rapid than that of the men above, as every ounce of dirt loosened at once falls down out of the way.

When the ore-body has been properly opened, explored, and ventilated by means of drifts, cross-cuts, and winzes, the work of extraction is commenced.

The first opening is made on the “track-floor” of the level—the floor on which are run the drifts and cross-cuts wherein are laid the car-tracks—and in the bottom of this opening or chamber are put down the sills for the first “square-set” of timbers.

The timbers used as supports in a mine are from twelve to fourteen inches square. The posts are six feet, and the caps five feet, in length. The upper ends of the posts are framed in such a manner that the ends of four caps may rest upon each, and leave a mortise in the centre, in which to insert the tenon of the post of the next “set”; on the top of this is a place for another post, and so the work of building up sets goes on to any height that may be required.

As the ore is extracted at the sides of the first set, the same squares of timbers are built up in those places, and there is formed a sort of pyramid of cribs, rising constantly as the work of extracting the ore proceeds. The top sets of this pyramid are secured closely against the ore, by means of large wooden wedges, and the side sets are also wedged up against the ore in the same way, as they are carried up. In this way the mass of ore overhead is supported at all points by the cribs of timbers, except here and there where chambers are being excavated in the ore-body for new sets.

Thus are squares of timbers constantly added, and the pyramid carried up till the ore has been worked out to the level above. If the level above has been worked out, it is already filled with the same square sets as are being built up from below, and the latter rise into their proper places and fit as neatly as the squares on a checker or chess-board.

The sets are six feet in height by five feet in width, and as they rise, floors of strong plank are laid upon each set. Thus there are seen floors some six feet apart from the bottom to the top of the level.

In these floors are square openings as for trap-doors, with short flights of steps leading from floor to floor. The floors are pushed out against the breasts of ore on all sides as the stope is extended. A light blast of giant-powder being exploded in the face of the ore-breast, the mass is shattered, and is then easily pulled down by the picks of the miners.

As the ore is dug down it falls upon the floors, from which it is easily shovelled into the wheelbarrows, by means of which it is carried to the chutes. These chutes lead down to ore-bins on the track-floor, where the cars are loaded which carry the ore to the main shaft and finally up to the surface, and out along a track which leads to the ore-house, from which it is sent to the mills. This is the method of timbering mines that was invented by Mr. Philip Deidesheimer, in the early days of Washoe, when he was superintendent of the old Ophir mine. The building up of timbers in square sets or cribs is found to be exactly what is required, as a cavity of any size, however great, can by this plan be filled up and its roof supported.

In order to still further secure the mine, it is usual to plank or timber up a section of four of these square sets, and fill them in from bottom to top with waste rock. Thus is provided a large column of stone reaching up to and supporting the roof of the mine. Such columns are constructed in a number of places, at suitable intervals throughout each level of the mine, and they are found to stand more strain than would all of the timber that could be piled into a level. Being built up of loose rocks they gradually yield for a time, but still stand as firmly in their places as before, whereas a solid column of stone would be crushed into a thousand fragments, and would let down the whole upper part of the mine.