80 FACTS IN AMERICAN MINING. 



saving in time of over five years. Great as is the magnitude of 

 the Sutro tunnel undertaking, there are several others eclipsing it 

 in extent and cost. In the Hartz Mountains a tunnel was con- 

 structed 14 miles long; and in Saxony a tunnel of 15 miles is iu 



course of construction, to drain the Frieberg mines. This has 

 already taken several years, and will require forty years more to 

 complete. 



A method of transporting timber to the saw-mills of the Carson 

 River valley is sufficiently curious and ingenious to deserve men- 

 tion. A Y-shaped flume is constructed 5 miles in length ; the 

 material is 2-inch plank, depth 2 feet, fall 1 in 33, carrying a rapidly 

 flowing stream of water. Heavy cordwood is thrown in, and trans- 

 ported the whole distance of 5 miles in eighteen minutes. At the 

 end of the flume is an iron grating, having the reverse shape af the 

 flume. The water escapes through this grating, and the wood by 

 its own impetus shoots upwards, along the incline, and is delivered 

 over the side. 



Tkeatment or the Metals. 



In nearly all the mills of the States some apparatus is used as 

 an adjunct to the stamper battery — amalgamating pans, arrastra, 

 Beath's grinder, centrifugal grinder, Ryerson's pulveriser, super- 

 heated steam apparatus, shaking tables, shaking pans, Chilian mills, 

 cast-iron barrels, Ambler's concentrators, barney's, Knox's, or 

 Wheeler's pans, or two or more of the above. 



On the adaptation of the treatment to suit the character of 

 the rock depends the skill and success of the millman ; in rock 

 containing fine gold the reduction must be carried to a point 

 according to its fineness, sometimes to an impalpable powder. 

 I have already adverted to the fact of gold often occurring in 

 large quantities in such a fine state of division as to be invisible 

 (even w 7 ith the aid of a magnifier). If the gold is coarse it is 

 better not to use a fine screen, for reasons which will presently be 

 shown. This is a subject deserving very careful attention. In 

 this country, until lately, the quartz was nearly all stamped with 

 uniform fineness, and at a fixed price per ton, instead of the price 

 being regulated entirely by the fineness of the mesh. The stamp- 

 ing of quartz to the necessary fineness often absorbs double or 

 treble the power and time occupied in ordinary crushing, the 

 latter frequently leaving more gold in the tailings than is extracted. 

 In the early days of California, it was not an uncommon thing to 

 send to the mill ore worth £100 per ton, and to get from it only £14 

 to £16, the loss being accepted as inevitable. Whether the same 

 sort of thing occurs here we can only say we are not sure about it, 

 but it is certain that many large parcels of tailings in this country 

 have been ascertained to contain more gold than the stone has 

 yielded. From personal observation I can say that there is plenty 



