136 
GRAVEL AND PLACER MINING IN ALASKA. 
[BULL. 26; 
sizes below No. 2, while in working on the Klondike benches the prac 
tice is in favor of butt ends even with larger giants. 
The giants used in Alaska are almost exclusively of California man 
ufacture, although in the Atlin and Klondike districts some of Cana 
dian make are used. The importance of using water as free ai 
possible from solid matter in suspension should be considered an( 
great care should be taken to trap all foreign material at the pressure 
box. The rifling in the barrel of the monitor and the boring of th< 
nozzle are also of the first importance, and operators will find i 
expensive to use other than standard and well-tried makes of giants 
A method of bracing giant is shown in fig. 28. In soft schist bed rock 
however, it is frequently necessary to brace with deadman and cable 
Scafe 
24 f nchea 
bed rock 
Fig. 28.— Method of bracing giant. 
METHODS OF PIPING TO SLUICE. 
It has been found that some operators in the north are in favor o 
setting the giant on the top of the bank and piping downstream. ThL 
is the practice on McKee Creek, Atlin district, and in the Nome anc 
Council districts. Although the duty attained by the miner's inch 
does not prove this to be advantageous, it should be remembered tha i 
the height of bank to be operated on is generally small — from 15 to 5( 
feet. There is little caving to be done with the pipe, and except ii 
the case of the rounded gravels of the Klondike " White Channel,'' i 
is thought that the water under pressure assists in moving the materia 
to the sluice. Experience does not indicate that the attempt to drive 
the gravel with the nozzle is very effective. 
The various precautions concerning keeping the gravel bank square 
the prevention of dangerous caves, and the necessity of continuous 
work during the short season are well known to the hydraulic minei 
in any country. In working the shallow gravel banks of Alaska r 
should be borne in mind that the giants must be frequently movec 
and the tail sluice extended. These operations consume time, and th( 
most expeditious system possible for performing them should be 
adopted at the commencement of the short season. 
Fig. 29 shows the method of rigging up a hydraulic mine on one 
of the narrow benches of White Channel gravel bordering Bonanza 
Creek in the Klondike, and PI. XXIII, B, shows a portion of the 
ground which has been worked as indicated in the sketch. 
