THE DISTRIBUTION OF GOLD IN SLUICES.
In cleaning
up sluices the largest portion (approximating 80 per cent.) of the
gold caught is found in the first 200 feet. The gross yield of the
Gardner's Point claim for the season of 1874 was $63,000 for 100 days'
run. Of this amount $54,000 were obtained in the first 150 feet, and
$3,000 were taken from the undercurrents. The remainder was found
lower down along the sluices. The first undercurrent was 790 feet
distant from the head of the sluice, and yielded 50 per cent, of the
total yield of the undercurrents. The second undercurrent was 78 feet
distant from the first, with a drop of 40 feet between them, and it
contained 33 per cent, of the gross undercurrent yield. The third
undercurrent was 91 feet distant from the second, with a drop of 50
feet between them. Its yield was nearly $500.
It
sometimes happens that a hundred or a hundred and fifty feet at the
head of a sluice are covered with gravel during the greater part of a
run. In such cases the gold is found farther down. In the North
Bloomfield tunnel the upper 300 feet of the sluice are generally filled
from one to five feet deep with gravel, and still this portion yields
much more amalgam per linear foot than the succeeding 300 feet of
sluice. The following data from the report of this company for the year
ending October 31, 1876, are worthy of note, as showing the position of
the gold in the sluices at " No. 8 " claim, where some 700,000 inches
of water were run, washing 2,919,000 cubic
yards of gravel:
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