HYDRAULIC MINING. 



61 



adjacent to the rivers a dry diggings." As localities of this kind could not 

 furnish room for the many thousands who came to California, search began 

 to be made on higher ground and away from the rivers, and quartz mines 

 were also opened at a very early period in the history of the country, the 

 outcrops of many of the veins being very conspicuous. The diggings having 

 gradually become extended to the flats above the rivers, and to higher 

 ground, where the gravel was much less rich than it had been in the river 

 beds themselves, so that much larger quantities of material had to be handled 

 in order to procure the same amount of gold, the necessity for improvement 

 in the system of attacking the gravel became apparent. This led to the 

 invention of the so-called "hydraulic method" of mining, which dates from 

 the year 1852, and is to be credited to Edward E. Mattcson, a native of Ster- 

 ling, Connecticut, and which as at present operated, with machinery and 

 methods greatly improved over those at first used, is of the highest value to 

 the State of California. 



As has been explained, the sluice is a contrivance by means of which an 

 almost unlimited amount of material may be washed; it is only necessary to 

 enlarge its size, and increase its length, giving it at the same time a propor- 

 tionate grade. It is a piece of machinery which requires almost no looking 

 after while in operation. After having run for a certain length of time, which 

 may be several weeks or even months, a "cleaning up" takes place, the object 

 of which is to obtain the amalgam which has become lodged between the 

 riffles'. After this has been done, the riffles are put back, those which arc 

 worn out being replaced with new ones, and the work goes on as before. 

 Such being the case, it is evident that the principal expense in washing with 

 the aid of the sluice will be in connection with getting the material into the 

 head of the sluice. In the early days, gravel was often taken to the rocker 

 on men's backs. Besides, the gravel where it occurs in heavy masses is usu- 

 ally more or less compacted together, so that it would have to be loosened 

 with a pick, before it could be shovelled up to be carried off. This loosen- 

 ing, and the transportation to the head of the sluice, as well, is effected with 

 great rapidity, and at a, small expense, considering the work done, by means 

 <>f the so-called " hydraulic method " of mining, the principle of which is 

 exceedingly simple. It consists in throwing one or more jets of water, 

 issuing from a, pipe with great velocity, against the face of the gravel bank, 

 which water in the first place loosens the gravel, and then washes it down 

 into the sluice. The force with which the stream strikes the gravel is 



