PITRINGTON. 
HYDRAULIC MINING. 
153 
should be made to fit over and outside of this casting, so that there 
will be' no leak. The casting should be rimmed outside to a depth of 
2 inches. The jacketing of the nozzle is considered very good prac- 
tice, as it prevents smothering with gravel. In the type of elevator 
here shown the advantage is claimed that the various parts, lining, 
hacking, first section above throat, top section, etc., are separate and 
merely lit together, being held by a ring of wooden staves, as shown in 
PI. XXV, A. This obviates the use of heavy castings. The upcast 
pipe is made of lap-welded steel, one-eighth inch in thickness, and 
either lead or flange joints can be used. In the plant described the 
pipe was in 18£-foot lengths and the joint was made by bolting together 
wooden blocks, 10 by 12 by 24 inches, with a half-round cut made to 
admit the pipe. The upcast pipe should be set at an angle of 60°. 
By far the most important parts of the elevator as regards wear are 
the throat and the hood which receives the impact of the gravel in the 
^ ! 
iPL 
« 
r— = 
• " : -= — = 
Illlllllllll 
;^M^^ 
°\m 
• 
1 ! ! 
ni\ 'K iH 
1 
if 
i 
^^fct N 
\mt£~V 
2 feet 
Fig. 33.— Hood in head box of tail sluice. 
head box of the tail sluice above. These two parts are manganese steel 
castings, and if the gravel is very sharp and siliceous may wear out in 
one season. For the 10-inch elevator the throat weighs 400 pounds and 
the hood 600 pounds (price 16 cents per pound in San Francisco). The 
manner of setting the hood in the head box of the tail sluice is shown 
in fig. 33. The upcast pipe is laid against an inclined framework of 
four lengths of 2-inch plank 2 feet wide, and extends directly into the 
bottom of the tail sluice. (See PI. XXVII, .1.) Leading to the throat 
of the elevator directly above the nozzle is a sluice box, which conducts 
the gravel either from the boxes preceding it or from a bed-rock 
sluice, which is carried back on grade in the pit bottom as fast as the 
gravel is piped down. On Glacier Creek the gravel is led to the ele- 
vator in 24-inch iron boxes on 6-inch grade, with or without rail 
rimes. After leaving the discharge of the upcast pipe the gravel 
passes through eight or nine 36-inch boxes, with T-rail rimes. The first 
