Note on the Shoaling of the Calif ornian Rivers. 119 



will bear a perpendicular column of water fifty feet high. 

 Sometimes the pipe will be eight inches in diameter where 

 it connects with the hose, and not more than two inches at 

 the mouth ; and the force with which the stream rushes from 

 it is so great, that it will kill a man instantly, and tear down 

 a hill more rapidly than could a hundred men with shovels. 

 One or two men are required to hold the pipe. They usually 

 turn the stream upon the bank near its bottom, until a 

 large mass of dirt tumbles down ; and then they wash this all 

 away into the " sluice," or plank or stone paved ditch ; when 

 they commence at the bottom of the bank again, and so on. 

 If the bank is 150 feet high, the mass of earth that tumbles 

 down is, of course, immense; and the "pipe-men" must 

 stand far off, lest they should be caught in the avalanche. 

 Such accidents are of daily occurrence, and the deaths from 

 tliis cause probably are not less than seventy or eighty every 

 year. Often legs are broken. When they are buried in the 

 falling dirt, the water is used to wash them out. The gold 

 contained in the earth is washed into the '' sluice," or long 

 ditch. Being heavier than the earth and gravel, it sinks, and 

 is caught by the "riffles" (cross-bars or obstructions) placed 

 here and there. At convenient intervals this auriferous mud 

 is washed, and the gold sifted out, or, if fine, combined with 

 mercury; after which the resulting amalgam is "retorted" — 

 in other words, the mercury is vaporised by heat, when the 

 spongy gold remains behind. Of course, some escapes ; and 

 in future times, when labour is cheaper in California than at 

 present, this mud, which forms great dreary flats in the vicinity 

 of hydraulic diggings, will be profitably rewashed.* 



The various processes of gold-mining have all greatly 

 altered the physical features of California ; but none of them 

 have had such an effect as "hydraulic" mining. Hills melt 

 away and disappear under its influence, every winter's 

 freshets carrying to lower and yet lower points portions of the 

 debris, while whole valleys are filled with clean, fresh-washed 

 boulders of quartz and other rocks. Meantime, the Sacra- 

 mento and the San Joaquin flow turbid with mud. Bars are 

 formed where none existed before ; and the hydrography of 



■^ Hittel: *' Resources of California," p, 254. 



