156 GRAVEL AND PLACER MINING IN ALASKA. [bull. 263. 
claim, with almost precisely similar geological conditions, where gravel 
was being handled by shoveling into li-yard derrick skips trammed 
on trucks to the derrick, lifted to a sluice, and washed with gravity 
water. Now, grant that the cost of the derrick plant was $10,000 
while that of the elevator plant was only $5,000. The water for the 
elevator, however, 500 miner's inches, represented one-tifth of that 
obtained by an elaborate ditch system, the proportionate charge of 
installation of which was $60,000. It is very unlikely that the life of 
either of these properties will exceed six years, and it can be easily 
seen that the amortization charge for cost of plant must be, less 
interest allowance, $17,000 in the elevator plant, as against $10,000 in 
the derrick plant. 
It would be unfair to entirely decry the use of the hydraulic eleva- 
tor in Alaska. On the other hand, it is a deplorable spectacle to see 
cases where expenditures of from $25,000 to $200,000 have been made 
to secure the use of water at a head, where the elevator is installed, 
and where it finally becomes apparent that loss will result in the 
operations because gravel can not be moved to the elevator in sufficient 
quantity. 
To take a very typical Alaskan case, assume a body of material which, 
handled at the rate of 700 cubic yards a day, can be worked out in six 
seasons; that the section consists of 2 yards of muck and of 1^ yards 
of gravel which has a tenor of $3 per cubic yard. This material can 
be all handled by the hydraulic method at an expense of 50 cents per 
cubic yard, actual working cost, including superintendence. In order 
to make this hydraulic method available a ditch carrying 1,000 miner's 
inches of water at lowest stage must be built at a cost of $100,000. 
Let this cost include the hydraulic equipment. Simple interest charge 
on the investment and maintenance of ditch and plant will amount to 
$90,000 additional. Allowing nothing for purchase of property, the 
five annual payments to amortization of plant fund will amount each 
to $38,000. Allow one hundred days each season actual working 
time. Then the amount per cubic yard which must be added to cover 
payment to the sinking fund will be 0.542 cents per cubic yard, or a 
total of $1,042. 
This cost will not be regarded as extreme by those who have had 
experience in similar undertakings. The operator has a choice of 
mechanical plants, by using one of which he could work the ground 
with great economy. In other words, the use of the h}- draulic eleva- 
tor in Alaska frequently defeats the object for the attainment of which 
the hydraulic method of mining is employed. 
