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

The mill tlmberS were sawed IN mill,
thus furnishing a good face for the
plank lining. The mill holes were rails
ed so feet, then lined; second so feet
was added, lined, and the first lining re-
paired. By the time the third SO feet
was up the first was usually ready for
refining. At places where the vein de-
fiected from normal dip, exposing the |
timbers unduly, double lining was put
on when the hole was built. This was
an exceptional case, nevertheless it is |
striking illustration of the possibilities
of mill hole construction with cribbed
timbers on a vein with a slight dip.
Where the delivery distance is short,
and spruce or other tough timber expen-
sive, balsam fir or 'quaking aspen"
may be used with perfect safety, if the
slopes are not to be withdrawn at some
indefinite time in the future. In that
case first class timber is to be recon-
mended, as the extra expense is more
than counterbalanced by the increased
durability.
| In framing mill hole timbers patterns
with varying tenon widths are used, and
care should be taken that the lemons are
of exact size, thus ipsuring perfect fit
and obviating trimmings in the stope
The shoulder should not be less than two
inches, and in holes having much dip
more is advisable. The use of nails at
the Joints is a pernicious practice to
cover up slovenly framing which may
prove expensive in case it is necessary
to replace timbers. Abrubt bends in
the crib should by all means be avoided.
An intelligent observance of the general
contour of the vein vertically will show
where shot or two into the wall is ad-
visable to avoid these and conserve the
timbers at that point. 1t is better to
line mill holes with Pinch plank when
first built at those places where falling
ore strikes, for two reasons: First, the
destructive effect of falling mass Of
ore is much less when the fiber of the
wood is parallel with the line of decent;
I and, second, the cost of replacing tim
DeI CUT Ill LWO WOQlo pay 4OA oS'~Ae esi
Innings. Exact comparison will estab-
| I'lish the fact that first class 2-inch plank
is by far the best material for lining
mill holes. ''T" rails and boiler plate
are expensive fads that never fail tc
bring disaster and annoyance with theil
s use. The reason for this is plain, as E
lump of heavy ore dropping on rivet
head or track spike held tightly against
7 a metallic face will snap off unless made
/ of an unreasonable size and strength
t The use of this form of lining tends alst
l. to take away one of the chief virtues o.
G ;he orbits mobility or the facilit.
c with which it may be bent. Wher'
{ ,ribbed holes are to be kept filled o
{ partly filled, they should be made larg
u enough to prevent Hanging up" AM
c carefully lined as built. The stull
le ed mill hole is admissible in veins of an
II size up to the point where the timber
-e become too cumbrous to handle, presup
posing that the walls are stable, an
l. are in general use on those veins o
? appropriate size where the slopes ar
IL 20 be filled with the broken ore reserves
e, It is very expensive method Of timber
I'd ing, as the labor expense entailed in cut
le ting the seats or bitches and properl
&c setting the stulls is frequently prohib
e, Etive. AS before stated, points like thes
tc should be carefully gone over before tn
al final adoption of this system. Stulle
ei mill holes are usually made five fee
16 from the centers of stulls, with retaiI
oy ing faces of split tagging and Zinc
Id plank or slab lining. 1t will be readil
yt seen that it is desirable, to have tt
&c hanging wall hitch cut, so that the VI
tc per and lower angles made by the stu
n and wall are 100 and 80 degrees respe
VI lively. 1t is false economy to u:
ng stulled holes without lining, as the co.
e, Of repairing or replacing timbers cut
hi falling ore is very great and far e.
a ceeds the cost of plank protectic
nd from the time it is put into use.
ar The. third class or stull and block sy
m, tenn, is really composite of the secol
re and fourth forms of construction al
fe furnishes very durable form of m
ful hole without entailing big. lumber b
ed for lining. o. the other hand, Il
to amount of tim Der required renders,
ch use unwise many places. The ado
,st ton of this form of construction
Is. Continued on editorial page