100 GRAVEL AND PLACER MINING IN ALASKA. [bull. 263. 
water is frequently used under slight head, and is known as ""bank 
head" or " by-wash" water. Various devices for more easily disinte- 
grating the bank and for disposal of the large bowlders and of tailings 
where natural grade is lacking will be later discussed. 
In California the application of hydraulic mining spread with great 
rapidity, especially within the drainage basins of San Joaquin and 
Sacramento rivers. This method was adopted also in other portions 
of the western United States and in other parts of the world, particu- 
larly in Australia and New Zealand. In the part of California referred 
to, extensive operations ceased, not because the gravel deposits were 
exhausted, but because of economic considerations other than those of] 
mining. The passage of an act of Congress in March, 1893, entitled 
"An act to create the California Debris Commission and regulate 
lrydraulic mining in the State of California," sounded the death knell 
of the huge mining operations which had changed the topography and 
blanketed many square miles of arable lands in the San Joaquin and 
Sacramento valleys with gravel tailings. 
The comments of J. D. Whitney, a written in 1880, concerning the 
application of hydraulic mining to California conditions, are as fellows: 
It is owing to a happy combination of favorable circumstances that the system of 
hydraulic mining has been so successful on the slopes of the Sierra Nevada. That 
the peculiar set of conditions which makes hydraulic mining possible is not often . 
met with is sufficiently proved by the fact that this system, which seems so admira- 
bly adapted to the needs of the Californian gravel miners, has hardly been at all suc- 
cessful in any other region. It has been tried again and again in the southern 
United States with almost unvarying loss; and even in Australia, where the mode oq 
occurrence of the gold is in many respects so similar to what it is in California, thereS 
are few districts where the hydraulic method can be applied. 
The first great need of the hydraulic miner is an abundance of water and with a 
considerable "head," so that the stream may issue with sufficient velocity from the 
pipes. 
An abundance of water can not be secured without extensive engineering opera- 
tions and the expenditure of a large amount of money. Extensive reservoirs must 
be constructed by building dams across the outlets of the mountain valleys, so as to 
impound the water coming from the melting of the winter's snow on the high 
Sierra, and the necessary canals — or ditches, as they are universally called by the 
miners — must be excavated to carry the water to the points where it is needed for 
use. The long, rapid, and rather uniform slope of the Sierra, in the mining dis- 
tricts, makes it possible almost everywhere to carry the ditches with such a grade 
and in such a position as to allow the water to be taken from them at a sufficient 
elevation to give the necessary head at the point of working. The great elevation 
of the important gravel masses and the deep canyons into which the whole mining 
region is cut up, afford, in almost every locality, the necessary facilities for arrang- 
ing the sluices and disposing of the tailings. 
A need equally as great, not sufficiently emphasized by Whitney, is 
adequate grade or slope of the bed rock for the moving of material. 
Experience has shown that the lightest grade of stream bed upon 
aLoc. cit., p. 62. 
