PUBINGTON.] DRIFT MINING. 89 
of the willows and moss-covered patches in the creek bottoms and 
along the low valleys appears to be entirely irregular. For further 
notes on the frozen and half-frozen conditions existing in the interior 
reference may be made to the matter presented under the heading, 
"Prospecting." 
Drifting operations in the creek deposits of the Klondike, Birch 
Creek, Fortymile, and Fairbanks districts of the interior are nearly 
always carried on in solidly and perpetually frozen ground. A nec- 
essary accompaniment of the work is the thawing of the ground by 
artificial means. Mr. Greenleaf W. Pichard has thoroughly investi- 
gated for this report the possibilities of using any form of the electric 
furnace for thawing the frozen gravel, and has reached the conclusion 
that electric thawing is impracticable. The thawing of ground which 
lies open to the air, by the combined agencies of sun and water, will 
be considered under the heading "Hydraulic mining." Artificial 
power, through the agency of the steam point, is only in rare cases 
applied in open-cut work. The Klondike district afforded a few exam- 
ples of this application of power, notably in connection with dredg- 
ing operations on Bonanza Creek, the steam-shovel operations on 
Bear Creek, and in two open cuts on Upper Dominion and Hunker 
creeks. PL XIV, B (p. 86), shows an application of the steam point 
to open-cut mining on Hunker Creek. It is difficult to determine 
the efficiency in open work, as, naturally, a portion of the thaw- 
ing is done by the sun. From the data collected, however, it does 
not appear to be any greater than its underground efficiency, which 
will be presently discussed. 
The method of thawing gravel underground by wood fires is 
expensive and, unless the conditions are very exceptional, is not used 
in those districts where transportation facilities permit the bringing 
in of boilers. 
According to experience on Deadwood Creek, Birch Creek district, 
the efficiency of a wood fire in creek ground was as follows: A fire 
taking three-fifths cord of wood (at $12 a cord) is built against the 
Pace of the bank. The pile of wood will be 18 inches wide, 2 feet 
ligh, and 25 feet long. Stones are laid up over the pile and a space 
s left to light the fire. The fire is lighted at 5 p. m. and left to burn 
intil 8 a. m. the next day. The stones, which quickly get hot, are 
•egarded as most efficient in thawing. On a 4-foot thickness of pay 
;his amount of fire will thaw, in the time specified, from 5 to 6 cubic 
v arc Is of gravel. This is at the rate of 9.2 cubic yards thawed to the 
ionl of wood, which is considerably less efficient than the method of 
gnawing with steam. Time, delays, and awkwardness of the method, 
•jnoreover, make wood-fire thawing the most expensive that can be 
jtdopted. The figures per foot for shaft sinking range from $3.16 to 
Iip7.50 in taking gravel from prospect shafts. The efficiency given in 
