purington.] HYDRAULIC MINING. 125 
plows, graders, and scrapers — were brought in and the ditch was 
completed to Hobson Creek. In 1903 the ditch was completed to 
the head of Nome River and a branch ditch was constructed to tap 
Snake River. Sixty-eight days were consumed in building the ditch 
from Hobson Creek to Dexter Creek, forty-eight days from Hobson 
Creek to Nome River. This latter figure includes the enlargement of 
the originally built Hobson ditch and the building of the Snake River 
ditch. 
The method of construction has been described above. A plow was 
used for breaking the furrows and the grader was used for bringing 
the cut to grade, 1 horses being used to a team. The ditch making 
was carried on at the rate of one-half mile per day, taking the tri- 
angular section off down to a level. This operation was followed by 
a second plowing. The grade stakes were set at a certain distance 
down the hill from the lower bank, and the men were directed to push 
the dirt so as not to reach beyond the line of stakes. From 60 to 70 
men were employed all the time, and the number of horses varied from 
50 to 100. The cost was reckoned at $100 for each horse for a period 
of eight months, and the wage of a man was reckoned at $7.50 per 
day. Two 1-horse teams were employed all the time to haul feed. 
(See PL XX, A.) 
The grading gang consisted of one 1-horse breaking plow and a 
grader, with 2 men and 8 horses. A scraping gang consisted of 2 
plows and 9 scrapers. There are thus 11 drivers, 2 men plowing with 
2-horse plows, 9 scraper men, and a foreman, beside the grader. The 
general cost of the smaller ditch is given at $2,300 per mile. It is to 
be noted that in this construction the upper bank was not sloped at 
all, as it was found that this sloping is very little use in the northern 
regions, the soil standing very well at various angles. 
The difficulties with ground ice were very great. At one place 800 
feet of such an ice sheet was found, and here the cost of maintenance 
is exceedingly high. The only way to maintain the ditch is to haul 
clay down the ditch in boats and dump it in. It is found that if suf- 
ficient clay is dumped on top of the ice it stops thawing, but this 
operation has to be annually repeated. At another point 1,100 feet of 
flume (8 feet by 33 inches, with double grade) were built over an ice 
sheet, and so far the ground has settled very little. One and one-half 
inch lumber is used in construction, at a cost of $200 per thousand 
feet. For each mud sill cuts were made into the ice from 2£ to 3 
feet. After the sills were in position the moss and tundra were 
rammed back over the ice. The cost of construction of this flume 
was $1,500, exclusive of the lumber. It is stated that the construc- 
tion cost much more than it would at present. 
At another point, across Manila Creek, an inverted siphon 1,000 
feet in length, of hydraulic riveted steel pipe, 40 inches in diameter, 
,11 gage, is used for 1,000 feet, at a cost of $10,000. It has a dip of 
