Mohave County miner., 1908-02-22
Mining by Tunnel.

Fifteen or twenty years ago, great tunnel enterprises in mining were quite fashionable, but in recent years they seem to have gone out of style.
 Colorado was the region particularly in which tunnel enterprises were more numerous than in almost any other state. Among those that have become famous among these great undertak- ings are the Sheridan tunnel in the Rico- Telluride district, in the San Juan; the Yak tunnel at Leadville: the Vidler tunnel and Newhouse tun- nel near Idaho Springs. Besides these are a score or more of others of mag nitude entitling each to consideration. The Newhouse tunnel is one of these enterprises which furnishes an excel lent example of the successful out come of a legitimate tunnel enterprise. This tunnel has been driven l7,54O feet at a cost of about 3O$ per foot. Royalties on ore hauled through this tunnel, it is calculated, will pay a handsome revenue on the investment. The Yak tunnel was described in this journal at length several months ago, and incidental mention has been made of numerous others from time to time. Many of the mining districts of Col orado are in rough mountainous re- gions where great adit may be driv- en that will cut series of veins which have been extensively worked in their upper portions-to depth in some cases of 1900 feet or more-far below the lowest levels. The tunnels re- lieves the mines of water and affords a convenient and inexpensive means of transporting ore to the surface. In driving some of these great tunnels the risk has been in the possibility that the veins might not be found to continue in depth, or if the Assures were intersected by the tunnel that the ore would be too low in grade to be profitable. Fortunately the veins have usually been found to continue in great depth and the value of the ore, if lower in grade, was still of the pro- fitable kind, owing to the greatly re- duced cost at which mining can be carried on through the medium of the tunnel, which practically eliminates all expense of hoisting ore, water ant waste, which is very large item il the economy of some mines. Whel connection has been made with th' workings from the surface the bes possible ventilation results, and alto gether conditions are much improved.
 Of course there is legal aspect t be considered when contemplating
 new tunnel enterprise. A tunnel sit may be located for the purpose of driN ing an adit across the strike of tn veins known to occur in the mountain and the locator of the tunnel is CT titled by law to 15OO feet on each vel his tunnel cuts that has not been pr' yiously found on the surface. In som instances the possibility of such di coveries appears to have been tt main incentives; in others, the tunn is driven after agreement with tf owners of the mines in line with u proposed adit-the object being u more economical mining and transpo tation of ore or the drainage of u mines, and very often both. I'll Cripple Creek drainage tunnels, no several in number, are of this latt class.
 Several mining companies ha driven expensive tunnels as priva enterprises-that of the Ontario min at Park City, Utah, being this class.
 As a general proposition, howeve tunnels are advisable when the ge logical conditions seem to warra them, and there are many plac where tunnels could be driven to go advantage where no such enterpri has been undertaken.-American Mi ing Review.
 The Mammoth Country.