puringtojt.] HYDEAULIC MINING. 147 
ered the pay. The bedrock is a soft slate of greenstone variety, although granite 
occurs at the head of the creek. The gravel to be moved is rather heavy in charac- 
ter, stones from 18 to 30 inches in diameter composing 50 per cent of the mass, 
though the usual diameter of the stones approximates 6 inches. 
In the season of 1904, a season being reckoned at 100 days, with 400 miner's inches 
of water available, 40,000 cubic yards of gravel were moved, at a cost not far from 
50 cents per cubic yard. It is expected that mining will be done in the future for 
40 cents per cubic yard, including all expenses. Mr. Maluin states that 35 cents 
would be a low estimate for the Atlin district, in general, for hydraulic work under 
the conditions obtaining on Bowlder Creek. Dirt is occasionally moved for 10 cents 
a cubic yard, and again patches of hard gravel are encountered which cost over a 
dollar. 
An average of 25 men are employed during the summer season at wages of $3 per 
day of ten hours, and board. The season is open from June 1 to September 15. 
Spruce and pine are obtainable on the property, though it is difficult to obtain boards 
wider than 8 inches. Sawed flume lumber costs $40 per thousand. 
The water for hydraulicking purposes is brought to the claim from higher up in 
Bowlder Creek by a flume 3,000 feet in length, size 24 by 24 inches, having a grade 
of 1 inch in 12 feet, It has an estimated capacity of about 700 miner's inches, but 
actually 400 inches is generally available at 150-foot head. The pipe line is 16-inch 
steel to the Y, then 14-inch to the two giants. Vancouver pipe is used, but the giants 
are California make. The average height of bank is 50 feet, and the giants have no 
difficulty in cleaning bed rock. 
The sluice is 1,400 feet in length and cost $6,000. It is 24 inches wide on a grade 
of 4 per cent, corresponding very nearly to 6 inches to the 12 feet. Bottom boards 
are 1£ inches thick, sides H inches thick, while sills and posts are 4 by 6 inches. 
It is possible to keep a drop below the end box of 35 feet for dump. In piping, 
the head box is kept within 30 feet of the bank, and four men for one-half day are 
teeded to place a new box at the head. Block riffles are used at the head of the 
luice followed by rails. Very little quicksilver is necessary, and it is found that no 
old is recovered beyond 250 feet of boxes. Undercurrents are not used. Bowlders 
ire removed from the pit by flat hand cars running on a steel track. If too large for 
his, which is seldom the case, they are plastered and shot with 75 per cent dyna- 
nite. The company is now in good shape to operate for a period of years, and esti- 
nates that the cost will not exceed 40 per cent of the product. 
The company leases a portion of its ground where the situation is not advantageous 
or hydraulicking, and this is drifted. Although the drifting operations are carried 
>n under great difficulties and require close timbering, the work is said to have been 
>rofitable. 
In the hydraulic mining of the "White Channel" bench gravels of 
he Klondike, the small amount of water available, generally from 100 
200 miner's inches, necessitates steep grades to the sluices. The 
fold is recovered with comparative ease because the bench gravels, 
fter being thawed, are easily disintegrated and washed, and clay is 
bsent from the pay streaks. The sluice shown on PI. XXIV, A, is 
arried in a cut in the outer rim rock, on u grade of L2 inches to the 
ox length of 12 feet. Twelve to fourteen boxes are ordinarily used. 
> 'he details of the sluice are as follows: 24 inches wide by 2<> inches 
eep, bottom of 2-inch and sides and lining of 1^-inch lumber; posts 
rid sills 2 inches square; sills set in bed rock; riffles of spruce blocks 
I inches high and 9 inches square. These cost 25 cents apiece and last 
