November 5, 1915.

THE COLLIERY GUARDIAN.

941

Coal Mines Inspection in 1914.

NORTHERN DIVISION.

Continued from page 890.

Dangerous Occurrences.

Thirty-two notices under this heading were received
during the year, and were classed as follows :—Explosion
of gas or coal dust, five; underground fires, six; breakage
of winding ropes, chains, or other gear by which persons
are raised or lowered, 20; overwinding, one.

Each of the five ignitions of gas occurred in naked
light pits, and four of them were due to a candle being
raised into a cavity in the roof containing a small accu-
mulation of firedamp. The other ignition was a some-
what peculiar occurrence, and took place only 10 ft. away
from the bottom of a sinking pit. After a seam had
been reached, and before continuing the sinking to a
lower seam of coal, a pump room was being made. A
short length of arching was put in from the shaft side,
and at the end of the arching a wall was built which
sealed off the strata, excepting that a hole the size of a
brick was left in it. While a workman was passing this
small hole some gas came out of it and ignited at his
candle. The cavity behind the wall had not been pro-
perly stowed up, and gas had accumulated. The force
of the explosion was sufficient to topple the wall over.

Early in the year a fire, fortunately unattended by
much danger, occurred in an underground engine house
in one of the Cleveland ironstone mines. No one seemed
able to explain how the fire originated, but it was pro-
bably due to oily waste being allowed to accumulate
beneath the seat, and when the night engineman left his
work he doubtless lighted his pipe, and might accident-
ally have thrown the burning match on to the waste.

An accident connected with the electrical installation
occurred in an underground engine house at Murton
Colliery, Durham, which may serve to show the possi-
bilities of danger which are hidden in switch boxes.
Owing to a fracture of the micanite insulation upon one
phase c* a three-phase 2,000-volt current, a short-circuit
was caused across the phases in a main switch controller.
The switch oil was heated up to flashing point and
ignited, and burst off the top of the switch box. Mr.
Nelson, electrical inspector of mines, after making an
enquiry, reported :i—“ This is an accident which, though
serious anywhere, would have been more serious had it
taken place in-bye, instead of near the shaft bottom.
There seems no reason to doubt the explanation offered
by the management, namely, that the explosion was
caused by vaporisation of oil due to the arc set up by a
short-circuit within the switchbox. The oil appears to
have been of good quality, and to have had a high flash
point. The only remedy it seems possible to suggest,
namely, the better ventilation of such switchboxes, had
already been applied at Murton Colliery. Though Such
explosions are rare, one might occur conceivably even in
a ventilated box, if the arc caused by a short-circuit
generated gas sufficiently quickly.”

Another electrical accident containing dangerous possi-
bilities took place in-bye in the Low Main seam of the
North Biddick Colliery, Durham. A double wire
armoured three-core cable, carrying a 500-volt alternating
current, served a small pump in one of the districts.
The circuit was protected near the shaft bottom by an
overload trip switch. A deputy going along the road
saw flashes from the cable, and he promptly telephoned
to the shaft forlhe current to be cut off, and sent for the
electrician. It was found on examination that the cable
had been punctured with blows from a sharp tool, such
as a pick. Fortunately there was neither gas nor coal
dust about; but, at the same time, there was plenty of
wood, which might have taken fire had the accident not'
been detected in time. Mr. Nelson, electrical inspector
of mines, investigated the occurrence, and reported :—
“ Examination showed the cable to be punctured,
apparently by blows from a sharp tool, such as a pick.
The overload trip switch which was supposed to protect
the circuit did not act. The reason the overload trip
did not act is because such protection is in no way sensi-
tive. The leakage current has to exceed the value at
which the overload trip is set to operate before the latter
is called into action. That is to say, the leakage current
must first exceed the working current by perhaps 100 per
cent. Clearly a leakage of any value up to this over-
load value might produce open sparking indefinitely with
only such protection as was provided at this colliery,
and, it may be added, with only such protection as is
usually provided below ground in mines. The con-
tingency of a cable damaged by a pick or a nail, or by
a fall of stone, may be held to be remote, but it cannot
be, ignored in all cases. The remedy, however, is to
provide leakage cut-out protection which is called into
action immediately any portion of the current—it may
be a small portion—leaves the conductors provided for
it to return to the generator by some other path; for
example, by the cable armouring or more directly via,
earth. When such a leakage occurs there is a ‘ fault ’ on
the circuit and the balance which normally exists at
every instant between the current which enters and that
which leaves the conductors of a healthy circuit is dis-
turbed. Leakage cut-outs are brought into action by
such disturbances of balance only, and they may be set
to operate with any degree of sensitiveness. If it is
desired to cut off the pressure from a circuit quickly
should a fault occur—for example, in the event of a
fall of stone on a cable in an atmosphere charged with
coal dust—the advantage which a leakage cut-out confers
over an overload cut-out is at once clear. There can be
no doubt that the protection of circuits below -ground
by this leakage method will become the established
practice in the near future.”

Fortunately the mines in the Northern Division are
characteristically free from gob-fires; several under-
ground fires have occurred in the past, however, and

while their actual cause was doubtful they may have
originated spontaneously. Interest, therefore, is
attached to the occurrence of a pure gob-fire which was
discovered in the Main coal seam in the Bichard Pit of
the Seaton Delaval Colliery on April 19, 1914. The fire
was not attended with much danger as no gas was
present, and it was not difficult to deal with. , The
method of working the seam was longwall, the gate roads
being 22 yds. apart. It was midway between two of
these gates that the fire started, at a point about 40 yds.
from the face. The gate packs were 3 to 4 yds. thick,
and were built with post and inferior coal. There were
many conditions favourable to the formation of fires in
the goaf of this seam, viz. : (1) About 21 in. of inferior
coal, containing much finely disseminated pyrites, was
thrown in the goaf; (2) about half of the timber set was
left in the goaf; (3) the seam was a little moist in places;
(4) there was a post roof which would tend to keep in
any heat generated, and the fissures formed in the post
would enable air to penetrate into the goaf. In order to
deal with the fire, a “ scouring ” road was driven through
the goaf at right angles to the gate roads. Fire was
found on both sides of this road, and was gradually dug
out. Attention was chiefly paid, at first, to the fire on
the in-bye side, in order completely to isolate the fire.
A water supply was quickly obtained from the rising
main. It was found, however, that the steam produced
had a very deleterious effect on the roof and several
small falls occurred on the return side. Flue dust
thrown on to the fire in quantity was found to be far
more effective. A considerable number of burning props
were found, and, as was to be expected, the pyrites in
the inferior coal near the fire showed various stages of
oxidation. As the fire was filled out the opening was
filled up with post stone embedded in flue dust, so that
the stowing was incombustible, and, as far as practicable,
airtight. Thermometers were placed in the goaf at
various places in the district to see if heating was taking
place elsewhere, and these were read and recorded
periodically by officials.

A fire occurred near the bottom of the upcast shaft
in the Busty seam of the Tursdale Colliery, Durham,
under somewhat peculiar circumstances. The fire had
apparently originated at a binding wheel carrying a
haulage rope in the intake airway, but close to the first
of a set of doors leading to the upcast shaft. The cause
of the fire may have been due to the wheel rubbing upon
the wood frame, or by a piece of hard stone having got
trailed into the rope box, and so fixed that the wheel or
rope may have been rubbing it and causing sparks.

There were six cases where winding engine drum shafts
broke during the year, and all connected with engines
which had been in use for many years. There was only
one case of overwinding while persons were being raised
or lowered, and this was at an upcast shaft completely
covered over with brickwork, so that the engineman
could not see the cage. A proper indicator, however,
was provided. The winder shut off his steam too soon,
and when he again opened the throttle he gave too much
steam, and carried the cage containing one man into the
detaching bell.

An event which might have had. serious consequences
happened on December 5 at Bebside Colliery,
Northumberland. A fire broke out in the fan engine
house and did considerable damage. A strong wind was
blowing at the time, and the smoke was carried towards
the downcast shafts. Although no one was below
ground at the time, it was found advisable (to cover over
the shafts so that the smoke should not be carried down
to the ponies. The fan was driven by eight cotton
ropes from a double cylinder engine. The exact cause
of the fire is unknown, but it appeared to be due to
some action on the part of the fan attendant. It is
believed that as he was opening a new box of matches
they exploded, and he dropped the box into the rope
race.

Probably one of the most unusual events which should
come under this heading occurred at the Blackhouse
Colliery, belonging to the Birtley Iron Company,
Durham. At this pit some exploration work had been
carried out in the Maudlin seam in the vicinity of an
old shaft about 41 fms. in depth, which had been filled
up with rubbish. This shaft is probably 200 years old.
The exploration had proved goaf at a point 50 yds.
beyond this shaft, and four shifters and two deputies
were preparing to draw out the timber in two of these
roadways. Owing possibly to defective field drains,
water had accumulated in the shaft, and the weight of
the debris so increased burst out the pack walls at the
shaft bottom at about 6 o’clock on the morning of
January 31, 1914. Almost the whole of the filled in
material rushed into the workings in the form of mud.
In connection with this accident, his Majesty was
pleased to present Joseph Cook with the Edward Medal
of the 2nd class. The colliery company also rewarded
him; his fellow workmen presented him with a gold
watch; and he was also the recipient of a certificate and
£10 from the Carnegie Hero Trust.

Prosecutions.

In accordance with instructions proceedings were
instituted in four cases against owners, agents, or
managers of mines. In regard to prosecutions of work-
men, a total of 311 persons were charged, and 300
persons were convicted and mulct in penalties reaching
the sum of .£278 10s. In 1913, proceedings were taken
against 258 persons, of whom 253 were convicted, and
the penalties amounted to £239 5s. lOd.

Ventilation.

A very large proportion of the coal mined in this
Division is obtained from bord and pillar workings,

and this system of work opens up great lengths of road-
way which are not in actual use. It frequently happens,
therefore, that if main air roads are not carefully isolated
by good stoppings, a great part of the ventilating current
escapes into these roads and is not conducted to the
face of the workings where the fresh air is required.
Again, where large areas of pillars have been extracted,
there are great numbers of roads having direct com-
munication with the goaves, and along these inflammable
or noxious gases may find their way to the working
places. It is mines such as these which have to be
carefully watched, and samples of air taken and
analysed to see that inflammable gas is not found in the
main intake within 100 yds. of the first working place
in a ventilating district. Some of the older mines have,
now and again, got very near the border line of the
provisions laid down in the Act, although in no case
has there been an actual infringement of the regula-
tions. In one or two cases, however, serious complaints
have had to be made as -to the ventilation in mines
worked on the longwall system. In one case the remedy
was almost entirely that of larger air roads near the
faces leading into the main return air roads. A longwall
face which is fairly straight should be easy to ventilate;
and if the gate pack walls are of sufficient size and
properly built, and the face systematically and
adequately timbered, should also not be difficult to
maintain. Many of the longwall workings in this
Division have stepped faces, so that the air instead of
travelling along a continuous open face has to proceed
around a series of steps, the side of each step usually
forming a very imperfect air road. A straight face
induces regular subsidence of the goaf parallel to the
line of working, while a stepped face produces
irregularity in the breaking of the roof; and inasmuch
as the roof naturally tends to follow the line of working,
the roof weight frequently crushes off the coal at the
low corner of the step, or causes a roof break and
subsequent fall at the coal side of what should be the
airway. In this wTay the ventilation is frequently
impeded. Experience has shown that in longwall step
workings one face should not be taken much beyond
5 yds. in advance of the next, or trouble will ensue.
During the year, 821 air samples were taken and
analysed, and these showed that the conditions, as a
whole, were satisfactory. It is still true that small
percentages of firedamp are not reported, and in con-
nection with shot firing this is far from satisfactory.

Shot>Firing and Explosives Used.

A very large quantity of explosives is used in this
Division, especially for coal getting; during the year
9,051,9041b. were used, and lb,644,784 shots were fired.
There still seems to be some misconception as to the
meaning of the clauses of the Explosives Order, and
doubt as to who may have possession of detonators.
There are still far too many accidents from the careless
handling of explosives.

The following are particulars of the explosives used
and number of shots fired :—Quantity used, 9,051,904 lb.
Estimated number of shots fired : By electricity,
7,012,173; by fuse, 1,094,354; by squibs, 8,538,257—
total, 16,644,784. Misfire shots : With electricity,
3,811; with fuse, 926; otherwise, 5,511—total, 10,248.

Rescue Work.

Ambulance and rescue work continue to maintain a
satisfactory position in the Division. Central rescue
stations, thoroughly equipped to meet the terms of the
Rescue and Aid Regulations, and each also possessing
all the advantages of an up-to-date fire station, are in
proper working order at Elswick and Ashington, in
Northumberland, and at Houghton-le-Spring and Crook,
in Durham. The rescue station at Brigham, in Cumber-
land, is now completed and equipped, and serves all
the Cumberland mines, with the exception of one or two
small mines, which have been exempted from the pro-
visions of the Order.

Signals.

*At many collieries the management have made their
own interpretation of the meaning of the code, and have
printed this, or painted it upon a notice board, for the
guidance of those concerned. While the interpretation
may be perfectly correct, it would, Mr. Wilson thinks,
be safer to keep to the wording as given in the Regula-
tions, about which there should be no ambiguity. There
is still apparently considerable confusion of thought on
the question of the visual indicator required.

Safety Lamps.

The use of safety lamps, both oil and electric, has
decreased during the year, and the lamps are practically
all in accordance with the Regulations, with the excep-
tion of a number of oil safety lamps which have not yet
been converted from four to five poles. Particulars
follow7 :—Flame safety lamps : Number in use, 117,773.
Method of locking: Lead rivets, 40,645; magnetic,
64,804; screws, 12,301; other, 23. Kind of ilium in ant :
Colza or colza and petroleum, 89,203; petroleum, 11,529:
volatile spirit, 5,431; other illuminant, 11,610. Method
of lighting : By electricity, 68,588; otherwise, 49,185.
Electric safety lamps :—Number in use, 6,987. Method
of locking : Lead rivet, 4,510; magnetic, 2,469; screw, 8.

Electricity in Mines.

There is little to complain of with regard to the obser-
vance of the Electricity Regulations in this Division.
The use of electricity has increased during the year to
the extent of slightly over 11,000-horse power. The
folio wing show's the aggregate horse-powder :—Number of
mines, 279. Surface : Winding, 11,118; ventilation,
18,644|; haulage, 10,063|; coal washing or screening,
13,4855; miscellaneous, 25,624J; total, 78,936|. Under-
ground : Haulage, 40,681: pumping, 42,657|: portable
machinery, 4,245|; miscellaneous, 3,291|; total, 90,875|.

Care and Treatment of Animals.

With regard to the treatment of horses and ponies,
which is regulated by the Third Schedule to the Act, a