felNGTON.] 
HYDRAULIC MINING. 
118 
ligher than in California, while in the ditches made on gentle slopes 
I Seward Peninsula c would be considerably higher. Its value can 
lot be known until accurate experiments have been conducted on the 
arious ditch lines. 
Examples of the discharge of ditches in California, given by Bowie, 
re as follows:" 
Locality. 
Length. 
Grade. 
Size. 
Dis- 
charge. 
iorth JBloomfield . . . 
)utch Flat 
Miles. 
55 
13 
20 
1(> feet per mile 
13J feet per mile 
7 to 8 feet per mile. 
8.65 feet top by 5 
feet bottom by 3^ 
feet deep. 
6^ feet top by 4 feet 
deep. 
9 feet top by 6 feet 
bottom by 4 feet 
deep. 
Miner's 
inches. 
3,200 
3, 150 
,a G range 
2,400 
In considering ditches and ditch building, the three provinces of 
laska, namely, the South Coast, Interior, and Seward Peninsula, will 
e taken up in succession. 
SOUTH COAST PROVINCE. 
In the South Coast province of Alaska the topography permits a 
ipid increase of head in short distances. (See PI. XVI, A, p. 114.) 
le ditch line of the Alaska-Treadwell Gold Mining Company, 14 miles 
length, delivers water from the penstocks above the mill — to which 
supplies power— at an elevation of 480 feet. As may be seen from 
le map (fig. 19), the ditch heads in Fish Creek 1,000 feet above the sea. 
he water at the upper penstock, midway on the ditch between Doug- 
s and Treadwell, is taken out at an elevation of 600 feet above the 
. The distance from the penstock to the nozzle is only 1,500 feet 
slope, and it may easily be seen what advantage is gained from the 
eep topography. The grade of the mountain, nearly 30 feet in 100,. 
such that were a sufficient amount of water available in one of the 
sar-by creeks no ditch at all would be required. The water could be 
$d out by a few hundred feet of flume to a penstock, and a pipe line 
Id directly from this to the mill. The Treadwell ditch line is com- 
Iksite, so far as its contained water is concerned, since it taps suc- 
■ssively Fish, Eagle, Cowee, Lawson, Paris, Bullion, and Ready 
J illion creeks. Its length is not extreme considering the amount of 
Uter obtained, but it is considerably greater than would have been 
ijcessary if all the w r ater could have been obtained from a single creek 
c river. 
"Bowie, op. cit., p. 139. 
Bull. 263—05- 
