PURINGTON.] 
DRIFT MINING, 
83 
winter drifting operations should be continued in that vicinity where 
timbering is necessary but thawing is not, and where the gravel can 
be trammed to surface through adit for $3 per cubic yard, including 
all expenses of extraction and sluicing-up in the spring. This is less 
than double the cost of drift mining in the Forest Hill divide region 
of California, where conditions are eminently favorable. 
Neglect to sample is the worst possible practice, as many lamentable 
failures have resulted from overconfidence in the value of the ground 
taken out, and the miner who confidently waits for the big wash-up 
before thoroughly knowing the amount of gold in the material he is 
handling is frequently doomed to disappointment. The method of 
sampling the dump, given under the heading" "Hydraulic mining" 
(p. 118), is to be highly recommended for all work of this nature. 
Where timber is scarce and costly, and wood for fuel has to be 
hauled from a distance, it is advisable to consider the entire abandon- 
Fig. 14. — System of opening drift mine. 
ment of attempts at winter work. The amount of gravel which can 
be hauled is less, and the cost per cubic yard is greater. The time 
spent in sluicing the winter dump ma} r frequently be more profitably 
employed in preparing for the summer. The ordinary small rig for 
drifting operations without timbering is shown in fig. 13. 
DRIFTING AND TIMBERING. 
Drift mining, whether the workings are approached by shaft or 
adit, can be most economically conducted by adopting the system 
which proved so successful in California. The mine is opened by a 
main tunnel or runway, 6 by 6 feet, which generally requires timber- 
ing, with logs 8 by 8 inches, 6 feet long, the sets having 5-foot centers. 
This runway is continued out to the end of the block of ground which 
it is proposed to work, say from 50 to 100 feet in ordinary Alaska 
operations. It is assumed that the runway occupies the longer dimen- 
sion of the ground and approximately the center of the pa}^ streak, 
say 75 or 100 feet in width. From the main tunnel drifts are run 
ransversely each way to the outer edges of the pay. These generally 
lo not require timbering in frozen ground. Fig. 14 illustrates the 
ystem of main runway and drifts. The gravel can now be breasted 
)ut, a face being carried the full width of the pay and the work being 
continued in two or more of the drifts, as desired, the breasts being 
lways carried toward the shaft or adit mouth. The drifts may be 
