purikgton.] DREDGING. 1()7 
this is possible, it should be borne in mind that the employment of 
gravity- sluicing water on a dredge entails numerous and largely 
untried difficulties. 
Some of the special difficulties actually experienced in the operations 
above described were distance from any repair shop, sudden rises of 
the river after two da} 7 s' storm that prevented persons from crossing 
and endangered the dredge, and repairs which were necessary at the 
beginning of the season, and which included chopping ice out of the 
inside of the hull. 
The dredge shown on PL XXX, B, in Niukluk River, was oper- 
ating only in prospecting work during the season of 1904:. It has 
5-foot buckets, open connected. Its rated capacity is 2,000 cubic yards 
in twenty-four hours, but the actual capacity can not be given. The 
dredge was fitted with a rubber belt conveyor for the stacker. This 
is said to give much trouble, as when it begins to freeze at night in 
September the belt continually slips. It was said that in previous 
operations the dredge in ten hours used 5 cords of spruce wood, cost- 
ing $12 a cord, and handled 800 cubic yards of material. Eight men 
were employed at $7 a day, gross. In the Niukluk River banks the 
bed rock, which is schistose limestone, is 10£ feet below the surface, 
and is overlain by 1 foot of moss or willow roots, 2^- feet of sand or 
muck, and 7 feet of rounded river wash mixed with angular limestone 
fragments. Willows grow on the unfrozen ground and moss covers 
the solidly frozen ground. No regularity in the distribution of the 
two is apparent. 
The success of dredging operations in the Niukluk appears to be 
extremely problematical. So far as the physical nature of the gravel 
goes, no difficulty should be experienced. Frozen areas, hard bed rock, 
uneven depth, and irregular distribution of the alluvial gold are, how- 
ever, serious if not insurmountable obstacles to the success of a dredging 
operation which in a superficial examination of the ground may appear 
attractive. 
COST OF DREDGING. 
It is manifestly impossible to give detailed statements of operating 
expenses in a work of this character, especially when dredging has 
been conducted in a desultory fashion and for a limited period. The 
costs given on page 38 include a certain amount each year for the 
amortization of the plant and the ground. Bearing this in mind, those 
having the slightest familiarity with the subject will probably admit 
that the figures, namely, 49 cents per cubic yard for unfrozen, 80 
cents for frozen ground in interior Alaska, and -13 cents per cubic yard 
for Seward Peninsula, are not excessive. 
For purposes of comparison there is given the following statement 
of the cost at Oroville, Gal., quoted in the Mining and Scientific Press, 
February IS, 1905, from the report of the Oroville Dredging and 
