124 
GRAVEL AND PLACER MINTNG IN ALASKA. 
[Bl'I.L. 2(«. 
intake near the head of Nome River the elevation is 572 feet." At 
Hobson Creek a large head 
dam has been constructed 
entirely of sod. The dam 
was started at bed rock and 
is 20 feet in width by 130 
feet in length and is provided 
with a waste gate 10 feet wide 
and 10 feet deep in the center. 
It has been found entirely 
satisfactory. The ditch, with 
its branches and laterals, is 
54 miles in length. Of this, 
the main ditch is 31i miles 
from Hobson Creek to the 
tunnel. This ditch, as far 
as the "X," was made 10 
feet on the bottom, 14 feet 
on top, with a depth of 3 
feet. It has a grade of 3.37 
feet to the mile. Seventeen 
miles of ditch were made 
from the head of Nome River 
to Hobson Creek, with the 
dimensions 8 feet wide on the 
bottom, 11 feet on the top, 
and 3 feet in depth, with a 
grade of 4. 5 feet to the mile. 
From the "X" to the tun- 
nel, as represented on the 
map, the ditch has the same 
- dimensions as the upper end, 
and a grade of 0.5 feet to the 
mile. The ditch was con- 
structed to carry 3,000 
miner's inches of water be- 
low Hobson Creek, and at 
the upper end to carry 2,500 
miner's inches. The actual 
amount of water available 
under average conditions is 
said to be 2,000 inches. The 
ditch was begun on July 6, 
1901, at the "X." (See tig. 
The following year 75 horses and the necessary equipment— 
1 . — Map of Miocene ditch. 
21.) 
a According to levels by U. S. Geol. Survey. 
