166 GRAVEL AND PLACER MINING IN ALASKA. [bull. 263. 
ity to have been successful in its operations. It presents a strong 
confirmation of the views expressed by Mr. Hutchins concerning the 
advisability of installing prospecting dredges for Alaska practice. 
During the season of 1903 and 1904 a dredge of the dipper t} 7 pe was 
operated in Solomon River, near the one above described. The dredge 
was constructed originally with a stacker, but this system was aban- 
doned and a separate hull was built on which a hopper and sluice were 
erected. 
The dredge cost $33,000 on the ground, and weighs, barges and all, 
400 tons. It is equipped with one yard dipper, which digs three-fourths 
cubic yard of material each time on an average. During 1904 the 
dredge was in operation fifty days of twenty hours each, and handled 
21,000 cubic yards, or an average of 420 cubic yards a day. 
The ground dredged is 9J feet in average depth, and was all handled 
by the dipper. No permanent frost was found in the river bed, but 
the annual frost did not leave the ground until July 15, delaying the 
commencement of operations until that date. Thirty days at the end 
of the season were lost on account of the breaking of the main cable 
operating the dipper, and there was no chance to repair it. 
The experiences with the ground in this dredging operation were 
especially interesting. It was found that in places the gravel in the 
river itself was frozen all summer. On July 20 there were 7 inches 
in depth of frost within 2 feet of the surface. This disappeared with 
the first heavy rain. The dipper cleaned the bed rock successfully 
where it was black schist. Where the bed rock was limestone the 
ground was drifted in the winter with much more satisfactory results 
than the dredging gave. 
The dredge employed in the two shifts seven men, at $7 a day, and 
one man, at $9.50 a da}^, without board. In twenty hours 3 tons of 
coal, costing $26 per ton, were consumed. 
The cost of dredging in 1904, including repairs to and maintenance 
of plant, was 50 cents per cubic yard. As in the case of the small 
dredge, the pay over a width of 200 feet, which was worked in places, 
was found to be spotted, varying from 30 cents to $12 to the cubic 
yard. 
It is said that the clay in the gravel prevented the water from sluic- 
ing gold from the bottom of the dipper, and tests showed that a saving 
of 95 per cent was made. The sluice was paved with Hungarian riffles, 
and quicksilver was used. 
The general opinion expressed by these operators was that dredges 
having a capacit}^ of not to exceed 1,000 cubic yards daily will pay 
in Solomon and similar rivers of Seward Peninsula if operated by 
electricity generated from a central water-power plant. The employ- 
ment of gravity-sluicing water was made a necessary condition. While 
