Year: 1874




In mining regions where the coal bed
are exposed on the fanks of the hills
caused by surface excisions, mines ar,
opened by drifting but where the field il
covered at all points by the associated
strata sinking by slope or shaft is necessar.
10 reach and win the coal. In each cas-
the manner of laying out the underground
workings is the same, and is determined
by the nature of the coal, and the roo
and flow OF the mine. Where the Goa
seam, pavement and top are hard, pillar
of small size are left for the support Of
the superencumbent strata where thest
conditions are reversed, pillars of extr,
strength and thickness are required. Tn.
depth below the surface has always al
important bearing on the amount of Goa
required to be left as pillars.


There are several methods in practice o.
laying out underground workings, viz
working with pillars OF Just sufficient
strength to allow the mine to advanct
without danger of a crush or creep, anC
with the object of leaving the pillars be
hind - working with pillars of large
proportions with the object of removing
part Of them after the rooms have beer
worked forward to the limit of the mine
and working without pillars called the
''lay wall system, wherby all the coal i,
removed as the workings progress, allow
ing the superencumbent strata TO fall down
close to the heads Of the miners az they
work forward. Several important con
siderations determine the manner of lay
ing out the mine, as the thickness, texture,
hardness, and softness OF the coal and the
everything rocks, the nature Of the alluvial
cover of the ground as to rivers, marshes,
lakes, towns, villages, etc. In British
practice, as also on the the Continent of
Europe in cases where the beds lie deep,
an effort is nearly always made to reach
the lower seams first, particularly where
the deepest Goals can be wrought out with
out injuring the upper seams.


In the early methods of mining little
regard was paid to the extraction Of pill
ars, the object being to remove as much
coal as possible, as the miners advanced,
as is very frequently the case in some dis
tricts Of the American Union at the pres
ent day. This method frequently ends in
q crush, creep or. sit of the workings,
whereby the whole economy Of the mine
is destroyed. Where the floor is soft, the
first stage Of destruction is seen in the
appearance of a curvature Of the workings
caused by the pillars beginning to sink
into the pavement This is followed by
the floor cracking loDgitudinally the
crack widens and the floor rises until it
reaches the roof The pillars now bear
part Of the pressure and become crushed
and cracked, till finally the whole becomes
dead and settled A crush is due to the
weight being thrown wholly upon the
pillars, in which case the floor is hard and
capable of bearing great pressure. The
pillars moulder OF flag and break of, piece
by piece as the enormous weight of the
superintendent mass is thrown upon
them, ending in their complete destruc-
ton.


Mr.. John Buddle, Of Wallsend, En-
gland, about the year 1880, devised new





styled the ''panel system, whereby the
workings are laid off in the shape Of quad
rangular panels in areas of eight to ten
acres each Around each panel an extra
pillar from forty to fifty yards thick is left
which is pierced through at proper inter
walls for the purpose of ventilation. The
pillars Of these panels or squares are left
very large and the rooms comparatively
narrow. The pillars can be withdrawn in
the panel as soon as the rooms are brought
forward to the limit Of the parallelogram
the miners removing both the pillars and
propwood until an area of 100 or 15O
square yards of waste is cleared, when the
massive ceiling gives way and falls down
without being able to make any impression
on the surrounding panels. By this
methed more coal is got, and the mine IL
saved from the danger of crush or creep
extending over whole area of the under
ground workings. In the old method, a
crash invariably overran the whole Of the
mine, and an outbreak OF water could not
be arrested, while the catastrophe of an
explosion Of firedamp spread through from
room to room, Obstructing aircourses, which
in many cases extended for thirty miles,
making it impossible to determine where
the disaster had occurred.


The long wall system is only practicable
in seams Of ordinary thickness but where
it is only applicable it is the best method
of removing coal Of any yet in practice.
Every ton in the seam is mined out as the
workings progress forward, the superin-
cumbent strata falling behind the miners,
upon the COB waste, or rubbish made III
the act Of mining the coal or blasting the
road, and which is thrown back so as tC
choke the crash as much as possible. BY
this plan ventilation is more easily anO
promptly maintained Increased economy
in getting the coal results from this system
and less propwood is required. Goals Of
eighteen inches in height have beer
wrought in England on this plan. Ii is :
favorite method of mining in BELGIUM anC
Saxony also in South Wales, in Scotland
and in many parts of England, but it il
only practicable in seams Of ordinary high
owing to the trouble and expense required
to collect jobbing materials to obstruct thu
crash in thick seams.


p. S.-The foregoing papers, written IL
great haste and without time for revision
only glance at the subject on which the!
treat. In future papers on mining, the
question Of mine ventilation, the noxiul
and inflamable airs of mines and the com
position of these gases will be treated NOR
elaborately. When the whole papers ar
completed they will be thoroughly revised
and published in book form, for the us
mainly Of practical men. A. r.


A Tough Old Couple.