Mat 8, 1914.

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1012

THE COLLIERY GUARDIAN.

exposed coal damp until it reaches the surface, in
clearing as much, of the accumulated dust as is
practicable, and in adopting means to render the
remainder innocuous. Mr. Williams concurs with
Mr. Redmayne in the view that the efficacy of stone
dust has been supported by the phenomena of this
explosion.

The evidence as to the electric signalling in this
pit was very. instructive, he thinks, though not
quite conclusive. Whenever a signal was given,
either by pressing the wires together or by drawing
a file or other piece of metal across them, sparks
easily visible must have been produced, both at the
signalling point and at the bell. The question is
whether such sparks, as produced at Senghenydd
Collieries, were capable of igniting an explosive
mixture of gas and air. It was made abundantly
clear that sparks may be not only visible, but
bright and luminous, and still be incapable of
firing, gas, and that the appearance of a spark was
no criterion as to its power in this respect. Nor
is the voltage of the battery, used as the source of
the current in itself a criterion, and it is wrong to
say loosely, as is frequently done, that a certain
voltage, say, 13|, will fire gas, while another
voltage, say 9, will not. . This voltage is only one
factor, and not the most important one. So that
nine volts under one set of conditions of batteries,
line and bell, may be more.dangerous than 12 volts
under another set of conditions, and it cannot be
too strongly emphasised, that all the character-
istics of the signalling installations must be taken
into consideration, and the prevailing impression,
that the voltage of the battery is the only thing
that matters, corrected. In face of the knowledge
gained in investigations on this subject, it appears
most desirable that the Government should at once
carry out an exhaustive series of experiments with
a view to determining what may and may not be
permitted, to be used in mines liable to outbursts of
gas. This system of electric signalling with bare
wires possesses, in its simplicity, ease and quick-
ness of manipulation and its reliability, so many
practical advantages over all others that its pro-
hibition would lead to a big increase of accidents
upon haulage roads, and the objection to visible
sparks incapable of igniting gas is sentimental
only. Mr. Williams sees no reason to discredit the
statements of the colliery electricians that when
measured by them during working hours, the
voltage never exceeded 9 on open circuit, although
the method of measuring the voltage might have
been improved upon by using a voltmeter from
which the total voltage of the battery as well as
that of the individual cells could be read without
calculation. It was,however,clearly shown that the
voltage on closed circuit in the case of old cells was
less than half that on open circuit, so that the com-
parison to be made between the experiments at New
Tredegar and the actual working condition at
Senghenydd is as between working pressures of 8.9
volts on the one hand, and something actually
below 6 volts on the other, and not between static
pressures on open circuit of 9 volts, and a possible
11.45 volts for a short time after a period of rest.
To his mind the evidence is quite conclusive that
the characteristics of the installation were such
that no spark capable of igniting gas could have
been produced. He was also satisfied that the posi-
tions of the journeys at the top. and bottom of the
incline were such that no signalling could have been
going, on when the explosion occurred. Any
sparking that may have taken place could,
therefore, be produced only by the accidental con-
tact of the two bare signalling wires. When two
wires are pressed together in any way the surfaces
that touch have an area many times larger than the
points of contact of a knife edge'across them would
have, and it is a well-established fact that the cur-
rent necessary to ignite gas increases in direct pro-
portion to the area of the surfaces in contact. The
further comparison must, therefore, be made as
between the small area of contact of the knife edges
at the rescue station, experiments, and the larger
area of the surfaces in contact of the two wires in
the mine, and this strengthens the conviction that
the possibility, of an electrical cause of the origin
of this explosion can be entirely dismissed.

Turning to the theories as to the place of origin
of the explosion, Mr. Williams points out that both
the doors in the Mafeking storage parting are
admitted by all witnesses to have been blown inbve,
one a distance of 11 yds., and the other 15 yds.,
and a heavy beam. 12 in. square weighing 500 lb.
walled into the brickwork above one of them was
carried inbye . a distance of 16 yds. It is dif-
ficult to conceive that the full violence of an
explosion could, have passed through these doors
without appreciably damaging them, and that the
backlash from it could afterwards have developed
sufficient force to. have caused such destruction in
the reverse direction, and it is far more likely that
the effects of the backlash are shown by the lighter
articles and by the coal blown off the trams at the
inbye end of the journeys that were standing on the
parting. The position of the water tank, the
empty trams at the outbye end, and the stone
driven into the outbye sides of the timbers and
other indications seemed to be more consistent with
an inward propagation. After discussing other
indications of force, Mr. Williams says the two
doors above referred to. as being blown towards
each other on the Mafeking level, between the turn
into the hard heading and the intake are signifi-
cant, as also is. the fact that the men in the
Mafeking district were able to leave their
working places and . collect into groups
before they were killed. Generally, the

great weight of evidence seemed to point against
the Mafeking hard heading being the point of
origin, while he can discover nothing that is incon-
sistent with the explosion having started in or near
to the main Lancaster level.

Turning to the cause of the explosion, Mr.
Williams regrets that he is unable to accept Mr.
Redmayne’s conclusions. As previously stated, he
eliminates the signalling apparatus from the list
of possible causes,, and the evidence is strong
against the probability of sparks or flame from the
friction of ropes on timbers, or on sheaves and
pulleys having been the means. The only causes
that remain are matches, sparks from stones fall-
ing against each other or against iron or steel, and
the flame of a lamp. Matches can be dismissed as
being highly improbable. The last possible cause
is the flame of a lamp, and it seems more natural
to attribute the explosion to this cause, which did
exist, than to the other two, of which the most that
can be said is that they are merely possible. At
the lamp station, 440 yards in from the pit bottom,
there was an open lighted lamp. Outbye of this a
fall did occur which gave off gas in dangerous
quantity for some time after .the explosion, which
had to be carried away in pipes, to the East side
crosscut, and though the most obvious is not always
the true explanation, it is reasonable to connect
these two facts together, and to say that they
suggest, at any rate, the most probable cause. He
is inclined to the view that a big fall did take place
on the level before the explosion, and that an out-
burst of gas accompanied it. . The roadway was
being widened by 4 feet to put in side walls on the
night before the explosion. This would tend to
weaken the roof and bring about a heavy fall par-
ticularly where there was gas under great pressure,
as there must have been here, the seam above being
solid all around this area. The gas liberated in
this way would be carried on inbye, but the volume
of air passing would be considerably decreased
owing to the fall, and.the stream of gas along the
roof could remain without dilution to a non-
explosive point for a. considerable distance, until
it reached the open light at the lamp cabin, .where
it would become ignited and flash back as an initial
gas explosion along the main road, disturbing the
dust, and developing into a coal-dust explosion of
great and increasing violence as it passed along the
roadways into the workings. Had the explosion
travelled the full distance along the main, level
from the storage unobstructed by falls, the violence
might be expected to have been much greater at
the pit bottom, to have shot farther.into the East
side, and raised the coal dust there into an explo-
sive cloud devastating those workings as well.

Mr. Williams believes that the fall on the main
level inside the No. 1 North, preceded the explo-
sion, and he does not agree with Mr. Re.dmayne in
the reasons which he gives against this. In the
first place, he contends that there would not have
been any perceptible rise in the water gauge at the
fan. The fall did not completely.block the road-
way, nor was this the only intake airway, and even
had it been, the effect on the fan of such fall would
be to lessen the volume of air. passing through it,
and so reduce the strain upon it. The water gauge
would be increased only if the speed of the fan rose
in consequence of the smaller volume of air. The
fanman had not looked at his water gauge for eight
minutes before he heard the “one thunderclap.” as
he called it. In the second place, the fact of the
fire being under the fall. and. not having spread
inbye, is capable of explanation better on the
assumption that the fall took place before the
explosion than after. An explosion of this magni-
tude uses up the oxygen of the air and carries with
it its products to such an extent that in its p.ath
there is nothing left which can support combustion,
and it is only at the end of its course where a
supply of fresh air can be obtained that the
intensely heated combustible matter can burst into
flame. Mr. Williams thinks, therefore, that the
timbers which first caught fire were those just
inside the arching, and that the quantity of air
which afterwards passed along in spite of the short-
circuiting. was sufficient to carry this fire back
along the level with great rapiditv and that it was
nrobablv the fall which prevented its extension
further inbve. The quantity of timber under and
projecting from under the fall would be great
enough to allow some air to go through, as was
found when the efforts to put out the fire failed,
and it was in this wav that the fire was communi-
cated from the burning timber outside. Tn the
third place, the absence of stones blown from the
fal] is not strange. A fall of this height takes
the form of a more or less rounded cone projecting
up into the cavity above, and any stones blown
from the ridge by the explosion would of necessity
strike the overhanging side of the cavitv in front
and not be carried beyond. Lastly, it is not pro-
bable that a fall some 200 yards away would be
heard at the pit bottom, and if heard would so
resemble the closing of a door or the rumble of a
journey as not to he taken notice of. He does not
believe that there was. more than one explosion,
which gained strength in some parts, and lost it
in others, but that the whole oscillation of the
explosive force was completed in verv few seconds.

With regard to the operations after the explo-
sion, the question of reversal of the air is the first
that arises, and on this Mr. Williams agrees
entirely with Mr.. Redmayne’s remarks. Much was
said at the enquiry as.to. the water sunplv at the
nit bottom, and the opinion of those who first saw
the fire was that no quantity of water could have

extinguished it. The larger the supply, however,
the better the chance, and he thinks it would be a
very wise precaution in all collieries which do not
naturally make a sufficient quantity of water at
the pit bottom, to instal a column of pipes in
each pit from a water supply on the surface, inter-
connected at each landing, so that in the case of
damage to one pit, the other would be available.

With regard to the use of breathing apparatus
for rescue work in the West York district return,
the evidence of Mr. Shaw and the experts in the
use of apparatus must be taken as conclusive that
the smoke was too thick for any attempt to be made
within such time as there might be any chance of
bringing, men out alive.

Believing as he does that the explosion was
caused by the presence of an open light in the lamp
cabin, Mr. Williams thinks that the new lesson, to
be learnt from this disaster is that in mines which
are dry and dusty and liable to, or working seams
which are known to be liable to, outbursts of gas,
no open light and no unlocking or opening of
safety lamps should be permitted underground,
and when the classification of mines provided for
in section 30 of the Coal Mines Act, 1911, is made,
there should also be a regulation to this effect
applicable to mines of the character of the deeper
steam coal collieries in South Wales. He is of
opinion that the explosion was not consequent upon
any breach of the Act or Regulations, nor . due to
any lack of precaution of a kind not required by
law., other than that w’hich may be attached to the
position of the re-lighting station, and while there
were some contraventions of the statute, they were
all, with the exception of the failure to complete
the means for immediately reversing the ventila-
tion, of the nature of neglect to comply with for-
malities of no importance in themselves.
___________________________________________________

THE IRISH COAL TRADE.

Thursday, May 7.

Dublin.

There is no change in any direction this week, the whole-
sale house coal trade being quieter, although the retail branch
has been a little more active owing to a break in the weather.
Prices of all qualities are unchanged, as follows :—Best
Orrell, 28s. per ton; Abram, 27s.; best Wigan, 26s.; best
Whitehaven, 26s.; best kitchen, 24s.; steam coals from
about 22s. per ton; best slack, 22s. ; house coal, retail, Is. 8d.
per sack; best coke, 20s. per ton. delivered. The following
are the pit mouth prices of Irish coals at Wolf hill, Queen’s
County:—Large coal, 20s. per ton; small coal, 18s. 4d. ;
nuts, 16s. 8d. ; beans, 15s.; peas, 12s. 6d.; culm (coarse),
10s. ; culm (in pond), 3s. 4d. ; culm (fine), 5s. Prices, f.o.r.,
Athy, the nearest railway connection :—Large coal for malt-
ing and kiln drying, 23s. per ton ; best small round household,
21s. 6d. ; nuts (washed), 20s.; beans (washed), 17s.; peas
(washed), 14s. 6d. ; lime burning culm, 12s. ; fine culm,
9s. 6d. per ton. The output at these collieries is steadily
increasing, as is also the demand in the inland districts, but
very little of it as yet reaches the city of Dublin. The
collier vessels arriving at this port during the past week
amounted to 51, chiefly from Liverpool, Llanelly, Irvine,
Troon, Ayr, Garston, Ellesmere Port,. Newport, Preston,
Partington, Point of Aaire, Saundersfoot, Neath Abbey,
Swansea and Maryport. The total quantity of coal dis-
charged upon the quays was 20,800 tons.

Belfast.

Business both locally and inland continues to be slow in
nearly all branches of the trade, but more particularly as
regards household requirements. Some classes are a little
easier, but best qualities of English house coal remain firm,
although supplies are now more plentiful. Stocks, upon
the whole, are about normal, and quotations generally are
unchanged, viz. :—Best Arley house coal, 27s. 6d. per ton;
Hartley, 26s. 6d.; Wigan, 25s. 6d.; Orrell nuts, 26s. 6d.;
Scotch house, 23s. 6d. ; Orrell slack, 23s. 6d. ; all less the
usual Is. per ton. discount. Current prices for steam
coals :—Scotch, 16s. to 17s. per ton; Scotch slack, Ils. 6d. to
12s. 6d. ; navigation steam, 17s. to 18s. per ton delivered;
Welsh steam coal, 17s. to 18s. per ton delivered. Cargoes
arriving in the port during the week were from Troon,
Garston, Ayr, Silloth, Workington, Ardrossan, Preston,
Newport, Maryport, Swansea, Partington, Glasgow and
Girvan.	___________________________

THE BY-PRODUCTS TRADE.

Tar Products.—The market is steady and prices generally
are well sustained. Benzols continue firm, while pitch
keeps steady. Naphthas show no change either in price or
demand, while carbolics rule quiet. Nearest values are :—
Benzols, 90’s .............................	1/1

Do. 50’s .............................	11/|

Do. 90’s North ....................... /10 to /10|
.......................

Do. 50’s North ......................... /10

Toluol ...................................	/10|

Carbolic acid, crude (60 per cent.) ......... 1/1 to 1/1|

.....................

Do. crystals (40 per cent.) .......	/3£

Solvent naphtha (as in quality and package)...	/9|

Crude ditto (in bulk) .................. /5|

Creosote (for ordinary qualities) ...........	/3,V

Pitch (f.o.b. east coast) ........................... 37/	to 37/3

Do. (f.a.s. west coast) ..................... 36/ to 36/6
Tar (ex-works, London) ................... 25/9 to 29/6

Sulphate op Ammonia.—There is not so much movement
as might be expected seeing the improvement that has
taken place in the home market, but prices continue firm in
all positions, and the general statistical conditions are
satisfactory. Closing prompt prices are :—

London (ordinary makes) ..........	<£12/3/9 to £12/5

............

Beckton (certain terms).................. £11/7/6

Liverpool .........................	£12/3/9

Hull...............................	£12/2/6

Middlesbrough.....................	£12/1/3

Scotch ports ....................... £12/7/6 to £12/10

Nitrate of soda (ordinary) per cwt. ...	10/

[Sulphate of ammonia, f.o.b. in bags, less 2| per cent, dis-
count; 24 per cent, ammonia, good grey quality; allowance
for refraction, nothing for excess.]