The square system of timbering, in use in most of our large mines on
the Pacific coast, was first introduced in Australia by Mr. W.H.
Patton, who adopted it in the Broken Hill Proprietary mines, although
it does not seem to be so satisfactory to the people there as to our
miners, who are more familiar with it. The accompanying description
and plans were furnished by Mr. Patton to the report of the Secretary
of Mines for Victoria:
"The idea is supposed to have originated in the German mines,
but in a crude form. It was introduced among the mines of the
Pacific coast of America some 20 years ago, by a gentleman
named Diedesheimer. Its use there is universal, and experience
has evolved it from the embryo state to its present
perfection. The old system and its accompanying disadvantages
are well known. A drive would be put in for a certain
distance, when it had to be abandoned until it could be filled
up with waste material and made secure. This process entailed
much expense. The stuff had first to be broken on the surface,
then sent below, trucked along the drives, and finally
shoveled into place. Ventilation was impaired and the drives
were filled with dust. The men worked in discomfort, and were
not in a condition to perform a full measure of labor. Under
the system as adopted in the Proprietary mine, these
disadvantages disappear. The cost is one-third less,
ventilation is perfect, and every portion of the faces are
accessible at all times. Sawn timber is used throughout; the
upright and cross pieces are 10 inches by 10 inches, and stand
4 feet 6 inches apart; along the course of the drive, the
cross pieces are five feet in length, and the height of the
main drives and sill floor sets are 7 feet 2 inches in the
clear. In blocking out the stopes, the uprights are 6 feet 2
inches, just one foot shorter than those in the main drives.
The caps and struts are of the same dimensions and timber as
the sill floor. The planks used as staging are 9 inches by 2½
inches; they are moved from place to place as required, and
upon them the men stand when working in the stopes and in the
faces. A stope resembles a huge chamber fitted with
scaffolding from floor to roof. The atmosphere is cool and
pure, and there is no dust. Stage is added to stage, according
as the stoping requires it, and ladders lead from one floor to
the other; the accessibility to all the faces is a great
advantage.
If, while driving, a patch of low grade ore is met with, it
can be enriched by taking a higher class from another face,
and so on. Any grade can be produced by means of this power of
selection. Opinions have been expressed that this system of
timbering is not secure, and that pressure from above would
bring the whole structure down in ruins. But an opinion such
as this is due to miscomprehension of the facts. If signs of
weakening in the timbers become apparent, the remedy is very
simple. Four or more of the uprights are lined with planks,
and waste material is shot in from above, and a strong support
is at once formed, or if signs of crushing are noticed, it is
possible to go into the stope, break down ore, and at once
relieve the weight."
[Illustration: THE SQUARE SYSTEM OF TIMBERING IN MINES.]
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