374 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 Range.* 
Similar statements may be made in regard to Australia,t — a region in so 
* To this must probably be added the ‘‘spotted” character of the gravels in the Southern Atlantic States. 
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. 
+ 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 cne 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.” 
