The Lambertville record. [volume] (Lambertville, N.J.) 1872-1968, 1886-12-01
SUBSISTENCE IN MINING LAND.
Methods of Extracting Minerals fro IN
Under Ground.

The alarming subsistence which took place
some time ago in Scotland on the North
British railway, near Prestonpans, and
which was fortunately unattended by any
accident, has doubtless added fresh source
OF fear to the nervous railway passenger.
That the permanent way of railway for
distance of about fifty yards should sudden
ly sink to the extent of two feet is almost in
comprehensive at first; and had this subsi-
dence occurred while the train was passing,
instead of Immediately afterward, the con-
sequences might have been disastrous. 1t
is the case, however, though it may not be
generally known, that subsidences- fortu-
nately only gradual and comparatively in
appreciable-are taking place over many of
our railway lines, and that minerals are
| actually being extracted from underneath
nearly every line of railway under which
there is any mineral to get There are two
recognized methods of working out coal.
The old method is what is known as the
stoop-and-room" or pillar-and-room Il
system; and the method introduced into
Scotland about the beginning of the present
century Is known Ms the Hlongwalln or
shropshire system of working. The first
system explains itself by its name. After
the bed of coal is struck, rooms" are
worked out, leaving "pillars or stoops 4"
to support the superintendent strata The
object to be attained in this system, as prac-
tised in the olden times was to have as large
room worked out, and as small stoop OF
| pillar of the coal itself left us was consist
ent with the safety of the mine and the sup.
port of the surface, whilethe mine was open.
But this system entailed the entire loss of
the pillars so left. To obviate this loss the
method now generally adopted is to drive
narrow rooms or passages, seldom exceed
Ing fourteen feet, through the seam, leav.
ing large pillars -about 75 per cent. of the
mineral-until the extremity of the available
coal is reached. When, however, no regard
is to be had for the surface, and the coal
has been thus worked out as far as can be
done, the miner commences to work back
ward, taking out the stoops or pillars as he
goes The whole roof of the mine then
comes down; and this is the most danger.
GUS kind of subsistence. II does not only
take effect Immediately above the place
where " STOPPING has been going on, but
1t also draws round about il.
The longwall," or Shropshire method of
working, is what is known as the system of
complete excavation; that is, the miner
takes out the whole coal as he proceeds,
leaving emily perhaps foot of the roof,
should the everything strata be soft, and
props up passage with wooden supports
as he proceeds, to enable him to keep an
open way to the face of the coal. The por-
lions worked out are packed on each side of
the road " with waste material taken out
with the coal. This method of working
though ii necessarily implies subsistence, is
on the whole the safest for hesurface, and is
generally the one adopted. In fact, as mine
raj landlords are paid, in lieu of rent, n
royalty or lordship on every ton of coal or
other mineral brought to the surface, and as
the tenant can more quickly extract the
mineral by the wooden props method, he IL
generally bodnd in his lease to work in this
manner.