PURINGTON.] 
DRIFT MINING. 
85 
tunnel after the points had been left in fourteen hours, averaged Si- 
feet, including taking- out the points, putting in timbers, keeping up 
the track, and driving in other points to a distance of 5 feet. The 
average height to which the gravel was taken out in a representative 
block was 4 feet. PI. XIV, A (p. 86), shows the remnants of old drift 
timbers in ground which has been hydraulicked subsequently to the 
drifting of the rich bed-rock pay. The cost of mining was $5.50 per 
Fig. 16. — Plan of drifting operations on Solomon Hill, Klondike. 
quare yard of area worked. In drifting out the ground it was found 
hat three points in a face 6 feet wide, allowed to thaw twelve hours 
nd then withdrawn, the ground being wC sweated" twelve hours longer, 
pould thaw all the ground. The sluicing was conducted in the ordi- 
nary way of piling up the dump and afterwards caving and hydraulick- 
ng with a nozzle into the boxes. The actual working cost of washing 
yas about 18 cents per square yard of area worked. 
