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RESUME AND THEORETICAL DISCUSSION 



abundant water. But a low tenor of gravel, even if accompanied by abun- 

 dant facilities for obtaining water, would be a fatal obstacle to success, were 

 the detrital deposits thin. It is the enormous thickness of the gravel banks, 

 in the hydraulic mining region proper, which gives permanency to the opera- 

 tions and makes them profitable. The plant cannot be rapidly shifted from 

 place to place, as would be necessary if the gravel deposits were not very 

 heavy, without great loss. This is certainly one of the principal reasons 

 why hydraulic mining has rarely, if ever, been successful outside of Cali- 

 fornia. Especially in the Southern Atlantic States, so often spoken of as 

 an excellent field for the introduction of this process, the auriferous detritus 



■ 



lies too thinly scattered over the surface to make its handling the object of 

 hydraulic mining operations on a large scale. What may be done there, in 

 a small way, is what has been designated in the preceding pages as surface 

 mining or sluicing. There are no deep placers, and no auriferous deposits, 

 other than the ordinary surface detrital accumulations, on the eastern slope 

 of the Appalachian Kange * 



Similar statements may be made in regard to Australia,! — 



a reinon in so 





* To this must probably he added the "spotted" character of the gravels in the Southern Atlantic State?. 

 Places appear to be very rich in gold ; but there has been in that region no such general commingling of the 

 detrital materials and consequent general diffusion of the metallic particles, neither was the original store of gold 

 in the bed-rock by any means so large as it was in the Sierra Nevada. There are, perhaps, some localities at the 

 South where sluicing may be done with the assistance of the hose ; and this, in point of fact, is what properly 

 constitutes hydraulic mining, the essential feature of which is the fact that the gravel is carried into the sluices 

 by the aid of a jet of water through a hose or pipe, and not by shovelling. 



t No mining region in the world, with the possible exception of some of the favored states of Central Europe, 

 can boast a more thoroughly regulated and skilfully managed mining department than that of Victoria. The full 

 and accurate descriptions of the mode of occurrence of the gold, of the distribution of the gravels, and of the 

 methods of working, contained in the official documents published at Melbourne, enable us to form a very clear 

 idea of the differences between the Australian and Californian auriferous deposits. In many of their most promi- 

 nent features the two regions resemble each other to a degree that may justly be called most surprising. But 

 the general type of the Victorian Tertiary gravels is that of the Tuolumne Table Mountain rather than of the 

 San Juan Divide. Narrow channels, rich in gold, deeply covered by volcanic accumulations, and workable only 

 through shafts and by drifting, are the rule in Australia. Heavy masses of gravel, uncovered by lava, and lying 

 in a position sufficiently high to allow of the application of the hydraulic process, on any such grand scale as in 

 California, appear to be entirely wanting. The sluice is extensively used in Australia for washing gold, and 

 the gravel is, in some localities, moved by the hydraulic method, that is, with the use of the hose. These 

 operations are, however, on quite a small scale as compared with those carried on in the Sierra Nevada. The 

 largest quantity of water used at any one claim — that of the Yarra-Yarra Hydraulic Gold Mining Company 

 —-seems to be 510 gallons per minute, equal to about fifty-two miner's inches, the pressure employed being 

 thirty feet. To quote the words of one of the best authorities (Mr. Peter Wright, Assistant Engineer for Water 

 Supply), "Hydraulic mining [in Victoria] will be practicable only in a few places. The character of the earths 

 which occur on our gold-fields, and the position of the auriferous alluvium, lying, as much of it does, at low 

 levels, will prevent the general use of this method, but improved modes of sluicing on a large scale will cer- 

 tainly be invented when the miners are able to obtain water at a reasonable price." 



