April 4, 1913.

THE COLLIERY GUARDIAN.

699

the testing apparatus by a bent cast iron pipe b. The
fine adjustment of the air velocity in the apparatus is
effected by a valve c acting on the injector nozzles by a
rack and pinion. The usual provision is made for testing
lamps in vertical, ascending and descending currents by
means of the branches e, d, f, and in other respects the
arrangements are of the usual character.

Figs. 6 and 7 represent a sectional elevation and plan
of the magazine for storing up to 4 cwt. of explosives.
This magazine is situated 120 yards from the nearest
building and 44 yards from the boundary fence. The
walls are of gravel concrete, measuring 18 in. thick at
the base and 6 in. at the top, and the whole is covered
by a thick layer of earth, a strong wall being erected in
front of the entrance. The floor of the magazine is of
cement concrete, covered with linoleum. Ventilation is
provided through an air shaft extending to below the
floor, the opening inside the magazine being covered
with a wire grating. Entrance to the store-room proper
is gained through two strong burglar-proof wooden
doors opening outwards. Detonators are stored in a
covered-in niche in the ante-room. Two low-pressure
steam radiators warm the magazine, and a lightning
conductor is provided.

The pit gas for the experiments is drawn from a rising
drive leading to the No. 6 bituminous seam in the
280 m. level of the Gneisenau Colliery. To collect the
gas, the mouth of this drive is closed by a concrete
barrier 39 in. thick and pierced by a siphon for draining
oft the accumulated water, whilst the gas is carried off
through a 2J in. pipe, which extends about 13 yards,
into the gas chamber. This pipe conveys the gas to the
No. 3 shaft 11 yards away up this latter, and then above
ground for about 1,200 yards to the testing station,
where it discharges into the gasholder which stores the
gas under a pressure of 6Jin. water gauge. The natural
pressure of the gas being too slight to lift the bell of
the gasholder, artificial pressure is set up in the pipe at
the pitmouth by means of a steam injector. The water
of condensation is removed by means of several traps
arranged at intervals in the pipe.

The gas contains 80 to 90 per cent, of methane and a
little carbon dioxide, the remainder being air poor in
oxygen. No other hydrocarbons or free hydrogen are
present. The quantity of gas that can be withdrawn
from the collecting chamber at a time is 1,750 to
2,100 cubic feet; and if more be taken, the methane
content falls quickly. A second source of gas, on the
same level and furnishing gas of approximately the
same composition, has recently been discovered and
tapped.

The coaldust for preparing explosive coaldust
mixtures in testing explosives is obtained by grinding
bituminous coal from the Gneisenau Colliery, and has
the following composition:—Solids, residue on coking,
73’2 per cent.; gaseous constituents, 25’4 per cent.;
water, 1*4 per cent. The ash content is 7'4 per cent.
The same dust, very finely screened, is also used in the
large gallery when the production of very powerful
coaldust explosions is in question.

NORTH STAFFORDSHIRE INSTITUTE OF
MINING AND MECHANICAL ENGINEERS.

An ordinary general meeting of the members of this
institute was held at the North Stafford Hotel, Stoke-on-
Trent, on Monday, when Mr. Hugh Johnstone (presi-
dent) occupied the chair.

Rearer Workings at Podmore Hall Collieries.

Mr. William Barber read a paper on the subject of
“ Rearer Workings at Podmore Hall Collieries, with
special reference to Alluvium saturated with Water.”

The Podmore Hall collieries lie westward of the Pottery
coalfield, in the western anticlinal region, on the Cheshire
dip, and are wedged in between the anticlina land western
boundary fault, forming a valley or trough-shaped area of
contorted coal measures. The seams lie nearly vertical on
Che eastern side and flatten out to the west, the anticlinal
being the saddle to which the Pottery section of the coalfield
rises, and from which the western section dips. The anti-
clinal is most marked in the vicinity of these collieries, and
attains a height of [about 774 ft. above sea level. The
western boundary fault is considered to be of great magni-
tude and extends along the whole length of the district; it
at present forms the limit of all coal workings in this
direction.

The rearer portion of this coalfield extends along the
western line of the anticlinal for a distance of about
2,000 yards, and ranges in depth from 80 yards in the upper
to 300 yards in the lower seams, the latter seam being found
near the saddle and the former farther west. In this area
the Miles Green fault is a special feature, as it cuts through
the belt of rearer coals, and at this point throws the seams
down north-eastward a distance of 35 yards, thus forming
in itself a small district about 700 yards in length between
the fault and the northern boundary, in which the greatest
difficulty has been experienced in the working of these rearer
coals..

The Ten-feet seam, which is the only one at present
worked in this area, and the greater portion of which comes
within 30 yards of the surface, is very friable and tender for
a few feet near the top. The seam has apparently suffered
from exposure in the first instance and afterwards been
covered by alluvium, probably washed there by some river
or stream, the upper portion consisting mostly of sand. The
ground is heavily saturated with water, which comes from
the natural watershed of the anticlinal axis running
through the west valley to the Cheshire plain. It may
here be noted that the extreme northerly point of this area
marks the dividing line of the watersheds or drainage, one
stream going in the direction of Newcastle-under-Lyme and
the other to the Cheshire side; and although every attention
has been given in order to keep the surface watercourses in
order, the workings have undoubtedly drained a large tract
of the surrounding district, as the deep alluvium cover is
favourable for conveying water over long distances.

Method of Working.

Rearer coals are usually worked on the pillar-and-stall
system. The method of procedure, under normal con-
ditions, when the seam is recovered, is to drive the main
winning levels from the point where the coal is reached
throughout the whole length of the seam to the boundary,
the point of recovery being as near as is practicable to the
centre of the area to be worked, so as to give equal lengths
of level or working face on each side. From off these levels,
at intervals of 100 or 150 yards, dips, termed “ jackholes,**
are driven to the rise in sets of three, 10 to 15 yards apart,
and, wherever possible, some roof coal or portions of the
upper and lower part of the seams are left in. The j ack-
holes are driven in the centre of the coal, as the places are
much easier to maintain when so driven, particularly in
thick seams. It is not advisable to make the roads wider
than is absolutely necessary. The centre place is used as a
screen for the coal whilst the dips are being driven, and is
finally fitted up as a cage-dip for hauling purposes, and
should therefore be kept perfectly straight. In the case of
the dips on each side of the latter, one serves for an intake
airway and travelling road, and is fitted up with wooden
ladders, and the other as the return airway.

The dips or jackholes are usually driven up 100 yards.
Two breadths are sometimes worked from one recovery by
driving a new set of levels and rise dips from off the first
100 yards breadth to the top of the second breadth, and then
working downwards. It is, however, best to recover and
work the seam in single breadth, particularly where there
is a long length of working face. When the jackholes have
reached the extent of the breadth to be worked, the centre
one isfletched or widened downwards from the top. in the
case of the Ten-feet seam the timber, formed of half-round
larch bars, is set in square frames fixed against the root
and floor, and secured with side props, and the whole laced
together longitudinally as the work prcceeds.

When the before-mentioned work is completed, the dip is
laid with four parallel rails, which thus form two roads, one
within the other, 4 ft. 3 in. and 2 ft. wide respectively, the
outer broad gauge being used for the cage to run on, and
the inner narrow gauge for the dummy or counterbalance
The cage is constructed to form a horizontal platform made
to suit the angle of the dip and fit the landings, so that the
full tubs of coal can be run on to it and secured with ordi-
nary hand-catches. The dummy is a solid casting fixed on

West Riding Miners* Relief Fund.—The delegates repre-
senting the agencies of the West Riding Miners* Permanent
Fand, meeting at Barnsley Town Hall last week, refused to
accept the proposals of the board of management to provide
for the present financial Crisis. Mr. C. H. Cobbold presided
Details of the schemes which had been presented by the board
of management for the consideration of the agencies have
already been published. No. 1 scheme provides for the
meeting of future claims only resulting from fatal accidents
with contributions reduced from 4d. to l|d. per week, with
the allocation of what is necessary from the present funds
to secure permanently the present benefits to widows,
dependents, relatives and children. No 2 scheme provides
for an increase of contributions by Id. per fortnight, with
present benefits continued, excepting a reduction of benefits
to disabled members after a certain period. The chief
objection raised to the first proposal was that the scheme
did not continue the payments to the old men. One
delegate said the trouble arose from the delay in payment
of compensation for accident. The cost to the owners was
only Id. per ton, and they had got 6d. a ton to pay it with.
The owners wanted to break down the permanent society,
so that a man had nothing to fight with when he was lame.
That was one of the reasons for the opposition. Another
delegate said there was not now the same need for the
payments in regard to minor accidents as before the Compen-
sation Act was passed, and they must fight their grievances
arising from that Act through other societies than the
permanent fund. The first scheme was defeated by 32 votes
to 29, and the second scheme was also defeated, after little
discussion, by 27 votes to 21. Various propositions were
made by the agencies bearing on the schemes, Wombwell
Main proposing the fund should be wound up from June
next; but these were either withdrawn or defeated.
Eventually a proposal from Darfield Main, that a vote of
all paying members be taken on the board’s schemes, was
carried.

wheels, and runs inside the cage lines, and at the meeting
passes underneath the cage. The cage and dummy are
operated by a rope and brake-wheel. When working, the
cage with the full load, when going down the dip to the
bottom level, pulls the dummy up, whilst the dummy
alternately pulls the cage with an empty wagon back again.
The road itself is generally laid on wooden battens placed
parallel to the line of dip, and bolted to strong larch sills,
the whole structure being secured by chains in several
separate lengths to special baulks of timber fixed across and
fastened in the side of the dip.

Whilst this work is proceeding, two or more headings
10 yards apart are being driven out on each side from the
top of the cage dip to the boundary or specified distance, as
the case may be, ready for drifting purposes.

Dealing with entering up, shooting and forming the goaf,
Mr. Barber said a narrow passage or thirling is first driven
to connect the level for ventilation purposes; then the
operation of working away the coal in small sections or
shoulders from the bottom through to the top of the pillar
is begun, so as to form an inclined working face of about
45degs., which is maintained as uniformly as possible.
During this time a considerable amount of timbering in the
form of stretchers and scaffolding will be needed for pro-
tecting and maintaining the workmen at the face until the
topmost pillar has been worked sufficiently far enough
back to admit of the goaf breaking in and being got under
proper control.

When the working face has been properly formed, every
effort is directed to secure the breakage of the goaf and to
accommodate it to the line of working face so as to form a
natural scaffold for the workman to stand upon and carry
out his work. The goaf, then lying parallel to the face,
forms a sort of inclined plane, and serves as an airway for
the ventilating current to pass through.

When the topmost drift has been worked back about
12 yards, the entering and opening up of the second pillar
below is proceeded with on the lines previously described;
and where two or more drifts are being worked, as is usually
the case, the working faces are kept a uniform distance
apart, the top drift leading by 12 yards and the second and
lower drifts following in order at the same distance.

The ventilation is carried from one place to another
through the goaf by setting props close together on the
slant from the roof to the floor of the tub road each time
that a dressing is worked up. A pack is built across the
road to tub-height at the edge of these props, which are
covered with dirt before commencing to shoot the goaf, so
as to prevent the rush from dislocating them. This pack
also serves as a stage for the loader to work upon, and the
drift below recovers some of the timber as the work
proceeds.

Each of these driftings as they proceed downward will
involve the important work of controlling the goaf first
formed in the top drift and will require considerable skill
and constant attention during the whole period of working
until the breadth of recovery is exhausted. In practice this
operation is termed “ shooting the gob.” The coal face is
worked away upwards to a thin wedge-shaped block at the
top of the pillar of sufficient strength to form a protection
and hold the goaf whilst the coal and other material are
cleared away or moved forward. Then from a safe distance
the block of coal is blown through with shots, thus
liberating the goaf, which slides downwards. It is thus
controlled and moved forward each time to suit the safety
and convenience of the workman and accommodated to the
line of working face.

Alluvium Difficulties.

This method of dealing with the goaf, as a rule, works
satisfactorily, although there are exceptions, such as when
the goaf hangs or when it presses and breaks away in large
blocks, necessitating great care in handling. Its manage-
ment may be said to present the most difficult task
associated with rearer work, forming, as the work proceeds
downwards, huge bodies of loose debris directly overhanging
and adjoining the line of face. The exact state of the
interior of the goaf cannot always be correctly estimated,
nor the action that is taking place therein; but experience
shows that occasions do occur when special difficulties and
danger; us conditions are precipitated thereby, and even
these circumstances have been much intensified in the
rearer workings of the Ten-feet seam, north of the Miles
Green fault, where the coal is 9 ft. thick and lies at an angle
of 80 degs., being to a large extent covered with an alluvium
saturated with water.

In working this area, following the line of rearers on the
southern side of the fault, where the coals are clear of super-
ficial deposit, it was assumed that the section on the northern
side would also come through to the surface; in fact, a
vertical shaft had previously been sunk in this area to a
depth of 60 yards, which passed through the Bullhurst
rear coal at the top and within 6 yards of the same seam at
the bottom of the shaft, in addition to which some shallow
coals had also been worked on the western side of the anti-
clinal in the same vicinity.

When the first set of dips were driven up in these Ten-
feet rearers, it was intended to drive through to the surface
chiefly as an outlet for the ventilation. The seam gave off
gas more freely than was usual in rearer workings, due, no
doubt, to the closely-lying cover on the coal, and when