1884.] “Hydraulic Mining" in California. 4^ 
feet of water, or 8000 miners’ inches ; and the value of the 
water paid for by the Blue Gravel Company in forty-three 
months, ending November gth, 1867, was 157,261 dollars, 
being at the rate of 15 cents of a dollar per miners’ inch ; 
and the proportion of water used to wash down 989,165 cubic 
yards of gravel was 17,074,758 cubic yards, or 17 J cubic yards 
of water to 1 cubic yard of gravel ; and when at work the 
quantity of gravel daily moved was 1298 cubic yards, and 
•the estimated cost to move one cubic yard of gravel was 
5 and 7-ioth cents of a dollar. But in the face of contin- 
gencies the Blue Gravel Company moved 1,000,000 cubic 
yards of gravel in four years, or at the rate of 250,000 cubic 
yards per annum, and the cost of washing each cubic yard 
stands thus : — 
. Cents. 
Cost of water, at 15 cents per miners’ inch 5*77 
Cost of labour, gunpowder, sluices, and su- 
perintendence i6-io 
21*87 
Or 2if cents of a dollar per cubic yard. 
Thus the gravel should contain gold to the value of 22 cents 
of a dollar per cubic yard to cover cost, and the value of the 
gravel referred to ranged from 20 to 45 cents per cubic yard ; 
and the cost of work done in shafts and tunnels, in the said 
Blue Gravel Company’s Mining claim, reached 100,000 dol- 
lars. But with the cost of the necessary canals, paid for by 
the Excelsior Water Company apart, the total cost amounted 
to about 1,000,000 dollars, and we must note that the latter 
company sold water to other mining companies. 
The gross yield in gold of the Blue Gravel Company in 
four years was 837,399 dollars, and in the year 1866 the 
returns from the Blue Gravel Company paid all the costs of 
the developments ; but in 1867 assessments were paid by 
the owners to meet the deficiency arising from the cost of 
sinking two new shafts, and driving fresh tunnels on the 
lowest levels, which evidently contain on the bed rock the 
richest concentrations. 
In smaller mining adventures of this description, involving 
less capital, large profits have been made in the gold-bearing 
zone treated of, by also not having invested in costly canals, 
which would not have repaid the latter investment ; and 
thus it is evident that the water companies are dependent 
blindly on the prosperity of the miners. 
I will now more minutely describe the adtual mining 
operations ; — The mining ground being sele&ed, a tunnel is 
