108 
GRAVEL AND PLACER MINING IN ALASKA, 
[BULL. 263. 
Exploration Company to the stockholders for the year ending Decem- 
ber 31, 1904, by F. W. Bradley, president. The figures given represent 
merely operating expenses, and do not include allowance for deprecia- 
tion of the plants and of the ground. It should be remembered, how- 
ever, that even adding these items of expense to the operating cost per 
cubic yard the number of yards handled per season is so large, as com- 
pared with that possible in northern operations, that the total California 
cost is not greatly increased. Eight cents per cubic yard is believed 
to be a safe estimate for the present total cost of gold dredging at 
Oroville. 
The table of lost time in the following quotation is especially inter- 
esting 1 as showing: that even under the favorable California conditions 
the actual dredging time of a presumably representative dredge 
amounted to only 67.2 per cent of the whole. 
DREDGING AT OROVILLE, CAL. 
Our No. 1, or $45,000 dredge, made the following record: 
Cubic yards dredged 
493, 150 
Gold yield per cubic yard, $0.1232; operating costs, $0.0562; operating 
profit, $0,067, or $32, 905. 7S 
Improvement, taxes, insurance, legal, and all other working expenses 
(except construction of No. 2 dredge) 7, 166. 
Surplus 25, 738. 91 
Our No. 2, or $75,000 dredge, should be ready to begin work next month (January, 
1905). Figuring on the data now available, the two dredges should make the fol 
lowing average annual record: 
Dredge No. 1 (first cost $45,000) 
Dredge No. 2 (first cost $75,000) 
Total or average 
Improvements, taxes, and all other 
working expenses 
Total 
Dredged. 
( 'ubic yards. 
520, 000 
780, 000 
1,300,000 
Operating- 
cost. 
Per cu. yd'. 
$0. 0530 
.0500 
0512 
0088 
0600 
Probable 
yield. 
Percu. yd. 
$0. 095 
Surplus. 
$0. 035 
Or a yearly surplus of $45,500. Our prospect information indicates that after reject- 
ing that portion of our land of doubtful value the property should have a life of 
from thirteen to fourteen years at the above estimated rate of dredging. 
C. H. Munro, superintendent, makes a detailed report of the company's < (itera- 
tions, from which the following is taken: 
Extraction. — The prospect value of the area dredged, based on the average value 
of the holes in and near the dredged area, was 16.64 cents. The extraction table 
herewith attached, which is computed on these figures, makes the extraction 74 per 
cent of the prospect value. 
The extraction amounted to 76.37 per cent of the prospect value, based on the 
proportional or fractional areas as influenced by each prospect hole. 
