Elk City mining news. (Elk City, Idaho) 1903-1913, 1904-05-07

ces,where the cost of hitch cutting
amounts to So, pen. linear foot of mill
hole. The stull and block hole is con-
structed by first tightly wedging a stull
in place between the walls, then filling
in behind the stull with fine stuff level
with the top. On top of this foundation
and projecting over the stull three to
six inches a course of blocks is laid,
another stull, more fine stuff, then
blocks and so on. The distance which
the blocks project over the stulls de-
durability of the timber, as we'll as the
probable wear to which the timber is
likely to undergo without endangering
the stability of the hole, for it must be
understood that the block and stull mill
hole is built to last the life of the stope
without repairing. 1t can be repaired,
of course, but it is slow, tedious work.
The timbers used as blocking should be
cut not less than two feet long and
carefully graded as to diameter when
laying. In this system of construction
all the refuse timber of mine can be
utilized to advantage. Where this
method is employed on small veins of
rich ore, and where more or less waste
rock must be removed from the stope
in order to secure working space, it is
necessary to clean the hole down after
using it for ore, as surprisingly large
amount will hang on the projecting
blocks. For this reason it is we'll to
have the projection as little as is COM
patible with safety. Yet if the Slopes
are properly handled this expense of
dressing down should amount to practi-
cally nothing, as the miner can make
the trip down, using a rope to prevent
accidents, in a short time.
The fourth, or all block system, pre-
sents commendable features that makes
it by far the most desirable one in GER
tain places where the cost of timber
of proper size is not to great
1t is true that it costs lot to build a
mill hole two feet square with three
inches to two feet long. Yet, in cases
where The vein is large and the ore
hard and heavy, with an extreme de-
livery dis lance, in the long run it is
economical to build the block mill hole
The judgment of foreman will tell
him whether the foot wall is sound
enough to be used for the principal
wearing side of the hole. If it isn't
don't build block hole. There are a
few points to remember, though, in or
der to secure satisfactory results from
the heavy initial expense. The timbers
should be sound and, if possible, air
dried; they should be of sufficient length
to remain in place in spite of the nat
ural wear and strain incidental to hard
usage; they should be laid by a thor
oughly capable, conscientious workman,
and the orifice should be large enough
to permit the passage of MANS body
easily in case the ore hangs up, or job
of repairing presents itself. 4 The
straighter the line of ascent the great
er the life of the mill hole, hence it
pays to trim the foot wall to a reason
able extent to secure this evenness.. A
block mill hole properly constructed
will lastSa long time subjected to the
hardest usage unless some mucker tries
to avoid breaking large Jumps of Ore
and blocks the hole. The resulting ne
cessity of shooting out the obstruction
with dynamite orthoisting it out withe &
windlass should result in two things
Firing the culprit and seeing that g
minimum charge of powder is used 81
shot Repairing ia powder shattered
block mill hole is one of the slowest
most disagreeable and expensive tasks
mine timberman has. Besides, the
patched place rarely holds when sub
jected to hard pounding.
The fifth, or rock faced mill hole, is
one made feasible only in rare instances
where the mineral may adhere to either
or both walls with central or adjacent
dixie of tough, hard blocky rock not
subject to atmospheric disintegration.
Where such physical condition exists
very efficient and durable mill holes
may be constructed by using the rock.
tying the courses every three or four
feet by laying split tagging back q
little from the edge of the rock face.
and spil1ing split tagging to each end
OF this cross piece, then filling the
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