purington.] HYDEAULIC MINING. 123 
passes through fractured material all cracks must be filled with moss. 
Too much care can not be observed in the latter detail, and, especially 
during the first weeks of use, men must be kept constantly traversing 
and repairing those sections where leaks are apt to occur. The stir ring- 
up of the water by men walking along the bottom of the ditch is a good 
practice in the early stages, for silt, in addition to the sod, is a most 
valuable factor in filling the cracks. 
A scraper will work to great advantage in decayed schist, which needs 
no lining, as it holds water better than any other ground encountered 
and cuts out less. Fluming does not pay when there is a possibility 
of ditch building. In fact, it has been often stated by men familiar 
with ditch construction, that where possible, it is profitable both as 
regards first cost and subsequent maintenance to build a ditch in place 
of fluming, even if the distance necessary to be covered by the former 
be ten times that of the latter. Many slopes apparently not permit- 
ting a ditch cut, owing to the presence of broken rock and talus slides, 
on close examination are found to be favorable, for if 2 or 3 feet of 
this loose material is moved there are excellent opportunities for 
comparatively cheap rock cuts. 
When, however, it is deemed impracticable to construct a ditch, and 
where a flume must be built crossing a gully, a very efficient founda- 
tion can be made by digging shallow holes, filling with gravel, and 
placing on top a wide plank to distribute the load. If the trestle rests 
an such foundations, and the underlying ice is not disturbed, much 
trouble from settling will be avoided. The following are a few of the 
sosts representative of ditching in various materials: 
Cost of ditch in g in nirious materials. 
Soft muck and tundra, per cubic yard $0. 75 
jrravelly dirt, per cubic yard .65 
decayed schist, per cubic yard 40 to .60 
3,ock work, fairly solid, per foot 1 . 75 
Schist in place, per cubic yard 1 . 00 
..oose rock, per cubic yard h 25 
Ditching in muck which heaves is very expensive, and no general 
igure can be given. 
A ditch carrying 1,000 miner's inches will cost, under fail' condi- 
ions, $2,000 per mile, One with the capacity of 4,000 miner's inches 
vill cost between $4,000 and $5,000 per mile. Though much affected 
>y varying local conditions a conservative estimate for general work 
s $1 per cubic yard throughout. 
The following account of the construction of the extensive water 
onduits built by the Miocene Ditch Company was obtained from 
dr. J. W. Davidson, the company's consulting engineer. 
The water is taken from Nome River and its tributaries for the most 
>art, although a small portion is taken from Snake River. At the 
