MINING. 303 



workmanship or scientific or literary education is necessary to 

 mastery in it. Nearly all the water used by miners is sup- 

 plied by ditches, which therefore occupy an important place in 

 the mining of California. Indeed, it may be said that without 

 them the mines of the State would be relatively insignificant. 

 At least four-fifths of the gold is obtained with the assistance, 

 direct or indirect, of ditch water. There are very few springs in 

 the mining regions, the bed rock being usually slate with per- 

 pendicular cleavage, through which the water soaks down to 

 the lowest levels. The permanent streams are found only at 

 long intervals, and run in deep, steep, and narrow channels. 

 Nature has furnished no adequate supply of water near the 

 surface for towns or for quartz mills ; so they, as well as the 

 hydraulic pipes and sluices, must depend upon ditch water, 

 which thus is an indispensable requisite to the production of 

 four-fifths, perhaps nineteen-twentieths, of the gold. It is for- 

 tunate that the mountain ridge east of the mining districts rises 

 high into the region of snow, where the moisture that falls 

 from the atmosphere in winter is condensed and retained until 

 summer and fall. But without the ditches, this moisture would 

 do little good to the miners, since there are few cainps near 

 springs or on the immediate banks of constant streams. 



223. Flumes. Flumes are usually made with boards, an 

 inch and a half thick for the bottom, and an inch and a 

 quarter thick for the sides. At intervals of two and a half 

 feet there is a support for the flume box, consisting of a sill, 

 posts, and cap. The sills are four inches square; the posts 

 three by four inches, and the caps one and a half by four 

 inches. To erect a flume 25 feet high, costs about twice as 

 much as to lay one on the level of the ground, and at 60 feet 

 it costs about four times as much. The annual repair of a 

 flume is about one-eighth of its original cost, in favorable cir- 

 cumstances. If the flume is left dry several months, the 

 repairs may be more, for the sun warps and splits the boards, 

 and draws the nails. A flume box, 40 inches wide by 20 



