PKOSPECTHSTG. 141 



may exist in that neighborhood in the upper levels, as there are no drifts 

 for any distance along the quartzite except on the fourth and sixth levels. 

 The company is now prosecuting a search in this direction with reason- 

 able hopes of success. In fact there is a great deal of ground in all the 

 upper levels of the Richmond mine which warrants systematic prospecting. 

 In the mines southeast of it, however, the limestone has been very thor- 

 oughly prospected down to the point where the two fissures come together, 

 and it is not likely that any very extensive ore bodies will ever be discov- 

 ered in it, although it will probably be worked for a long time to come, for 

 the sake of the small masses of ore that have been ovei'looked or neglected. 

 The structure of the country in these mines has been fully explained 

 and the existence of a second limestone wedge, below the lower belt of 

 shale, has been pointed out. The obvious method of prospecting this ground 

 is to sink shafts through the lower belt of shale northeast of the present 

 workings and to drift in the underlying limestone. Such a system of pros- 

 pecting is at present being carried on in the Eureka, and if successful the 

 example of this company no doubt will be followed by the others. A cross- 

 section of the old and new workings of the Eureka is given in Plate VIII. 

 As the two fissures in the Richmond mine are still very far apart, the 

 same methods of prospecting which were followed in the upper levels are 



continued below. 

 \ 



Methods of prospecting on Prospect Mountain. The methods of prOSpeCtillg followed 



in the large mines of Prospect Mountain do not differ much from those in 

 vogue on Ruby HiM. In the small mines the ore is usually followed from 

 the surface down, either by vertical or inclined shafts, and the ore is ex- 

 tracted as the conditions of the ground permit. The Ruby-Dunderburg 

 and Hamburg mines, as well as several others, are worked systematically 

 with perpendicular shafts and levels run at stated intervals. 



A portion of Prospect Mountain is being prospected by driving tunnels 

 from both sides of the mountain at those points where the nature of the 

 ground permits of obtaining a great depth with a comparatively small 

 length of adit. As a means of opening mines tunnels are in general expen- 

 sive and unsatisfactory. Usually the distance to be driven in order to attain 

 any considerable deplh is very great; the tunnel is nearly useless in explor- 



