1are arranged on two different systems; for
either the square ends of the
timbers, which reach from the hangingwall to the footwall, are fixed into corres
ponding square holes in the timbers which lie along the hanging or footwall,
or the upper part of the end of one and the lower part of the end of the other
are cut out and one laid on the other. The great weight of these joined
timbers is sustained by stout beams placed at intervals, which are deeply set
into hitches in the footwall and hangingwall, but are inclined. In order that
these joined timbers may remain stationary, wooden wedges or poles cut
from trees are driven in between the timbers and the vein and the hanging
wall and the footwall; and the space which remains empty is filled with loose
dirt. If the hanging and footwall rock is sometimes hard and sometimes soft,
and the vein likewise, solid joined timbers are not used, but timbers are
placed at intervals; and where the rock is soft and the vein crumbling,
carpenters put in lagging between them and the wall rocks, and behind these
they fill with loose dirt; by this means they fill up the void.
timbers, which reach from the hangingwall to the footwall, are fixed into corres
ponding square holes in the timbers which lie along the hanging or footwall,
or the upper part of the end of one and the lower part of the end of the other
are cut out and one laid on the other. The great weight of these joined
timbers is sustained by stout beams placed at intervals, which are deeply set
into hitches in the footwall and hangingwall, but are inclined. In order that
these joined timbers may remain stationary, wooden wedges or poles cut
from trees are driven in between the timbers and the vein and the hanging
wall and the footwall; and the space which remains empty is filled with loose
dirt. If the hanging and footwall rock is sometimes hard and sometimes soft,
and the vein likewise, solid joined timbers are not used, but timbers are
placed at intervals; and where the rock is soft and the vein crumbling,
carpenters put in lagging between them and the wall rocks, and behind these
they fill with loose dirt; by this means they fill up the void.
When a very deep shaft, whether vertical or inclined, is supported by
joined timbers, then, since they are sometimes of bad material and a fall is
threatened, for the sake of greater firmness three or four pairs of strong end
posts are placed between these, one pair on the hangingwall side, the other
on the footwall side. To prevent them from falling out of position and to
make them firm and substantial, they are supported by frequent end plates,
and in order that these may be more securely fixed they are mortised into
the posts. Further, in whatever way the shaft may be timbered, dividers
are placed upon the wall plates, and to these is fixed lagging, and this
marks off and separates the ladder-way from the remaining part of the shaft.
If a vertical shaft is a very deep one, planks are laid upon the timbers by the
side of the ladders and fixed on to the timbers, in order that the men who are
going up or down may sit or stand upon them and rest when they are tired.
To prevent danger to the shovellers from rocks which, after being drawn up
from so deep a shaft fall down again, a little above the bottom of the shaft
small rough sticks are placed close together on the timbers, in such a way as
to cover the whole space of the shaft except the ladder-way. A hole,
however, is left in this structure near the footwall, which is kept open so that
there may be one opening to the shaft from the bottom, that the buckets
full of the materials which have been dug out may be drawn from the
shaft through it by machines, and may be returned to the same place again
empty; and so the shovellers and other workmen, as it were hiding beneath
this structure, remain perfectly safe in the shaft.
joined timbers, then, since they are sometimes of bad material and a fall is
threatened, for the sake of greater firmness three or four pairs of strong end
posts are placed between these, one pair on the hangingwall side, the other
on the footwall side. To prevent them from falling out of position and to
make them firm and substantial, they are supported by frequent end plates,
and in order that these may be more securely fixed they are mortised into
the posts. Further, in whatever way the shaft may be timbered, dividers
are placed upon the wall plates, and to these is fixed lagging, and this
marks off and separates the ladder-way from the remaining part of the shaft.
If a vertical shaft is a very deep one, planks are laid upon the timbers by the
side of the ladders and fixed on to the timbers, in order that the men who are
going up or down may sit or stand upon them and rest when they are tired.
To prevent danger to the shovellers from rocks which, after being drawn up
from so deep a shaft fall down again, a little above the bottom of the shaft
small rough sticks are placed close together on the timbers, in such a way as
to cover the whole space of the shaft except the ladder-way. A hole,
however, is left in this structure near the footwall, which is kept open so that
there may be one opening to the shaft from the bottom, that the buckets
full of the materials which have been dug out may be drawn from the
shaft through it by machines, and may be returned to the same place again
empty; and so the shovellers and other workmen, as it were hiding beneath
this structure, remain perfectly safe in the shaft.
In mines on one vein there are driven one, two, or sometimes three
or more tunnels, always one above the other. If the vein is solid and
hard, and likewise the hanging and footwall rock, no part of the tunnel
needs support, beyond that which is required at the mouth, because at that
spot there is not yet solid rock; if the vein is soft, and the hanging and
footwall rock are likewise soft, the tunnel requires frequent strong timbering,
which is provided in the following way. First, two dressed posts are erected
and set into the tunnel floor, which is dug out a little; these are of medium
or more tunnels, always one above the other. If the vein is solid and
hard, and likewise the hanging and footwall rock, no part of the tunnel
needs support, beyond that which is required at the mouth, because at that
spot there is not yet solid rock; if the vein is soft, and the hanging and
footwall rock are likewise soft, the tunnel requires frequent strong timbering,
which is provided in the following way. First, two dressed posts are erected
and set into the tunnel floor, which is dug out a little; these are of medium