APPEJS^DIX. 



Hydraulic Mining, 



The extraction of gold from soils, as distinguished from veins m 

 the solid rock, has been carried on most extensively for the past fifty 

 years upon the Pacific coast of the United States and Can'ada, and what 

 is known as hydraulic as distinguished from "placer" mining has been 

 brought to great peifLcticn there. California has b:en more systemati- 

 cally explored and her resources estimated in this respect than Canada. 

 Those of Canada are yet but partially known, but the probability is that 

 they will prove far greater. According to the State lilineralogist, Cali- 

 fornia has already produced over one thousand millions of dollars in 

 gold from her auriferous gravels — in the working of which over one 

 hundred millions of dollars have been invested. This gold was obtained 

 from the beds of ancient rivers where it is found covered with drift and 

 forest, which must be washed away by the power of water, before it is 

 reached. California has four hundred miles of these ancient water 

 courses, estimated to contain an 'average of two millions of gold per mile, 

 or $800,000,000 in all. Besides those which may be called ""'free milling" 

 deposits, there are ancient channels where the gold is found in cemented 

 material and cannot be washed out ; and, again, there are one thousand 

 miles of ancient channels in which the gold is "lava-capped" and can 

 only be reached by " drifting " for it. These lava-capped channels are 

 estimated to contain $500,000,000. 



For hydraulic mining the power canal or " ditch •■ should have an 

 elevation of at least one hundred feet above the working level ; and this 

 may be increased to five hundred feet without becoming unmanage- 

 able. The higher the head the farther it will throw an eft'ective stream, 

 and such head is necessary when working against a high bank in order 

 to secure a safe distance for the "giant" attacking it. 



The elevated ditch terminates in a large wooden tank called the 

 " pressure box," which feeds the pipe descending the slope to the field 

 of action. This pipe is constructed of wrouglit iron or steel sheets, 



