120 GRAVEL AND PLACER MINING IN ALASKA. [bull. 26* 
Where such a mass of ice is met sod and moss must be extensively 
used, and both the first construction and annual maintenance will be 
much greater than in other portions of the ditch. For an account of 
the method of dealing with such ice sheets see the description of ditch 
building in Seward Peninsula. 
In the Fairbanks district so little ditching has been done that no 
results gained from experience were available. The frozen ground 
has, however, been found so bad for ditching that the cost of annual 
maintenance is from one-fourth to one-half as much as the first cost of 
construction. Such expedients as patching with canvas have been 
adopted as a temporary makeshift. The small ditches which have 
been constructed are run with as flat a grade as possible to avoid cut- 
ting out. Here as elsewhere in the interior the use of sod for lining 
the sides of the ditches can not be too highly recommended. 
Small reservoirs in the creek beds for impounding sluice water are 
in use and will be described in connection with open-cut mining. 
SEWARD PENINSULA. 
The following notes regarding the building of ditches have been 
contributed by Mr. Guy A. R. Lewington, of Nome, Alaska, manager 
of the mining properties belonging to the North American Transporta- 
tion and Trading Company: 
Ditch building in Seward Peninsula has become one of the most serious ques- 
tions with reference to economical mining and the general stability of the whole 
mining industry. Water under pressure for hydraulic mining is the all-important 
condition, and to this end I submit the following, which may be of some interest to> 
those contemplating investment in this section. 
The necessary equipment consists of plows, scrapers, and graders of the usual kind 
in use in the States, and, of course, a camp outfit of tents, both for living and stable 
purposes. 
The conditions to be contended with in this country are different in almost all 
respects from those which have come under my observation elsewhere. The most 
serious of these is the building of a tight and strong ditch over "glacier," « of which 
much is encountered wherever ditches have been constructed. Under this condition 
it has been found best to dig as shallow and broad a ditch as possible, not digging 
much below the moss, and to build the outer bank of the ditch up to the required 
height by the use of the sod which covers the whole country. This sod in a short 
while settles and knits itself together, and thus becomes a very serviceable bank. It 
will not cut or wear out, and the older it gets the better it becomes. When, however, 
it becomes evident that the bottom of the ditch is cutting and wearing away, sod again 
must be resorted to, and by lining the bottom of the ditch with it the trouble may 
soon be overcome. In this way a ditch can be made over perpetually frozen ground 
where otherwise it would be impossible. Much ditch has to be constructed over 
loose stones with little or no sediment between them. In this case the ditch must 
be lined with sod and all holes must be filled by tamping sod into them as far as 
possible. This being done it will be found that the water traveling through the 
a The buried ice sheets. 
