GOLD MINING m COLOEADO. 511 



worked out, but, when seen by the writer, there were reserves of consider- 

 able extent in the lower levels. The vein in the bottom of the mine was 

 looking very well, being from eight to twelve feet wide in the third level and 

 carrying a strong seam of solid ore, as well as a wide belt of good stamp- 

 rock. This mine usually sends all its ore to the stamping mill without 

 selection of the first-class. According to the statement of the mining captain, 

 about three-fourths of the entire vein-matter is fit for crushing, of which one- 

 tenth part would be suitable for smelting, if desired. The average product 

 of all that is sent to stamps is stated at six ounces of retorted amalgam per 

 cord, equal to $12 or $15, in coin, per ton. The present owners of the mine 

 are developing their property with a view to permanent operations and eco- 

 nomical management. The central, or main, shaft has been sunk vertically 

 to its present depth, and timbered up in a very substantial manner. It is 6 

 feet wide by 11 feet long, in the clear, divided into two compartments, one 

 for hoisting and the other for pump and ladder-way. It is timbered from top 

 to bottom with 8-inch and 10-inch squared timbers, framed in sets that are 

 placed three feet apart vertically. The ground through which the shaft 

 passes is sufficiently firm to allow of sinking for 50 or 60 feet without sup- 

 port, so that the timbering can be put in from below upward. When a 

 suitable depth has been reached to make timbering desirable, a firm support 

 is afibrded for the first or bottom set by cutting the necessary "hitches" in 

 the solid rock and heavy timbers are put in place across the shaft, resting on 

 the foundation thus provided. When the first set, consisting of the two end 

 pieces and two wall-plates, framed together at the corners, is in place, the 

 cross-timber for the partition resting in gains cut in the larger pieces, the 

 posts or studs, three feet high, are raised at the corners and in the middle, 

 opposite the partition, and on these the succeeding set is laid. Each set, 

 when in proper position, is strongly secured by spiling, or wedges, driven in 

 firmly between it and the wall-rock at each corner and opposite the partition 

 timbers, so that it is immovable, independently of other support. The tim- 

 bering of the shaft is cased with plank on the outside, and the space between 

 this and the wall-rock, when everything is completed, is filled with waste- 

 rock. The hoisting compartment is likewise lined with 2-inch plank inside, 

 to facilitate the passage of the hoisting bucket. 



