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THE COLLIERY GUARDIAN.

April 18, 1913.

quencher, because it would rise more quickly into the
air.

He questioned whether Mr. Severs was doing wisely
in actually wetting his stonedust, because it might cake.
When, however, slightly damp, but still flocculent, it
sometimes stuck better to the sides than when applied
bone-dry. Fluedust would not cake like shaledust,
which must remain dry. In a pit which was moist of
air in the summer and dry in winter, shaledust would
compare badly with fluedust in that respect. Mr. Severs
was undoubtedly right in pointing out the general use
of a hygrometer, but that did not supply an answer to
the speaker’s question—one of great personal interest to
managers — upon the practical use of its daily or
periodical examination under the Mines Act and
Regulations.

He could not at all answer Mr. Leybourne’s question,
which should be addressed direct.

The Lighting Efficiency of Safety Lamps.

Mr. T. A. Saint, B.Sc., contributed a paper on “ The
Lighting Efficiency of Safety Lamps.”

He stated that the object of his investigation was the
lighting efficiency of safety lamps of standard pattern.
The conditions under which the tests were made were as
follows: — The room in which the candle-power was
measured was very similar to a heading in a mine, and was
about 6 ft. in height and 60 ft. in length. One end
remained entirely open, and at the other a window was kept
slightly ajar to maintain a through draught of air. The
temperature was about 46 degs. Fahr., and remained more
or less constant. The photometer was placed at the window
end of the room, as if at the coal face. The photometer used
was a standard form known as the “ Flicker," and consisted
of a scale along which the lamp to be tested and the photo-
meter slid. The standard lamp or candle remained fixed at
one end of the scale, the support holding the lamp to be
tested being placed on the other side of the photometer and
moved by a handle towards or away from it, as might be
required, until the light on the one side balanced that on
the other. When that had been brought about, the flickering
hitherto seen in the telescope of the photometer dis-
appeared. A 200 volt 8-candle power incandescent lamp
was used as the standard, but, as that was of too high a
candle-power for comparison with a safety lamp, a resistance
was introduced into the circuit and a voltmeter inserted
across the terminals of the lamp, by means of which the
candle-power of the standard could be accurately regulated.
The standard lamp was first tested against a Board of Trade
standard candle which burnt at the rate of 120 grains per
hour, as ascertained by careful tests. The candle-power of
the standard lamp proved to be 1’69, at which it was kept
constant. The lamps tested were (1) the Small Donald,
(2) the older type of Small Donald, (3) the Large Donald,
(4) the Marsaut, (5) the Mueseler, (6) the Davy, (7) the
Stephenson or “ Geordie,’’ (8) the Clanny, (9) the Scottish
Davy, (10) the Deflector, (11) the Routledge and Johnson,
(12) the Wolf and (13) the Protector. In lamps Nos. 1
to 11, oil was used; in Nos. 12 and 13, spirit. Five different
blends of oil were used, with specific gravities varying from
0’82 to 0’889 and compositions from 100 per cent, mineral to
100 per cent, vegetable, costing from 9d. to 2s. 9d. per
gallon. The spirit was benzine of 0'765 specific gravity,
costing Is. per gallon. The wicks were selected according to
the oil used. Mr. Saint made no statement in the text of
his paper as to the results obtained, but embodied them in
17 very exhaustive tables as an appendix to the paper.

The Jherria Coalfield.

Mr. Geo. Harold Greenwell’s paper on “ The
Jherria Coalfield (India) and its Future Development ”
was open for further discussion.

Sir Ralph P. Ashton and Mr. Allan Greenwell
wrote that the Indian coalfields were of rapidly
increasing importance to the world and were attracting
some of the best British mining talent. The author
was to be congratulated on his effort to make their
conditions more widely known in this country. He was
more favourable to the claim of the East Indian Rail-
way to have been the promoter and supporter of the coal
industry than were most of his contemporaries and
predecessors. History showed that, in its inception,
that railway had neglected the coalfields in order that it
might divert traffic from the rivers to its lines, and that
it had ever since lingered behind the demand for extra
facilities. At present the mineral industry was partly
strangled for want of transport. As to the area
worked, the author’s use of the words “ taken up ” was
ambiguous. Presumably he meant that the mineral
rights in 23,100 acres, out of 58,843 acres, had been
acquired by 53 companies. It did not follow, however,
that all that area was worked or workable. As a rule
the original owner had parted with his entire rights in
a “ mouzah ” or village. The use of the term “ exposed
area ” gave the idea that the strata were in part covered.
On the contrary, unlike the Raneegunge coalfield, which
dipped under the Deltaic alluvium, the Jherria field was
well defined and its boundaries were ascertained. The
ironstone shales and Upper Damuda series were

Prof. P. P. Bedson associated himself with Prof.
Louis as to the composition of the dust which should be
used. As to the thickening of oxygen, it did seem
reasonable to think that the thicker, the purer, one made
the oxygen, the more rapid and complete would be the
combustion ; but, in that connection he cited a familiar
experiment to the contrary, showing that the dilution
of oxygen, even by mixture with the nitrogen of the air,
made the air, apparently, more active as an oxidising
agent than pure oxygen itself. It was a common experi-
ment, with yellow phosphorus, to demonstrate that
phosphorescence did not take place in pure oxygen, but
that, if the pressure on the oxygen were reduced, the
phosphorescence made its appearance, so that the dilu-
tion of the oxygen by the nitrogen of the air appeared
to make the oxygen more active.

Mr. Fryar called attention to the question as to the
amount of dust which should be used in order to make
a pit safe. He did not think that any manager who was
troubled with a dusty pit knew what a relief it was when
he had got that pit stone-dusted.

Mr. Blair (Whitehaven) said it seemed to him that
coaldust was always being deposited in the pits
and that, however much stonedust they put down,
sufficient coaldust would ultimately be added to make
it liable to an explosion.

Mr. Severs said he had begun to apply stonedust in
one of his pits—a very dusty pit. Notwithstanding that
he got the grey colour on the roof and sides that
Mr. Blackett got, in a very short time it was all covered
up again, and as black as before. They had applied a
good deal of the stonedust in a wet state. He thought
the surface of the fluedust was more liable to be larger,
on account of its flocculent character, than would be the
case with ordinary shale. He thought it was just
possible that the hygrometer might be useful. A man
did know, by its use, when the air that went into a mine
was likely to take up moisture from the sides or the
dust that was lying about the mine, as well as when it
was likely to deposit moisture.

Mr. Ford said he found that shaledust had a very
much better sweeping action than had fluedust. Were
they safe, even if they had 100 of stonedust to one of
coaldust, if the latter were lying on top, or should the
mine be stone-dusted at stated periods ?

Mr. C. C. Leach remarked that some seams were
naturally stone-dusty, where there was a soft fireclay
bottom. He asked if Mr. Blackett could give them any
idea of the number of people who, after explosions, were
found alive and well owing to the stoppings being
blown out.

Mr. E. A. Laybourne asked what information the
Home Office had to go upon in order to lay down the
law stating that stoppings had to be such a tremendous
thickness.

Replying, Mr. Blackett said if Dr. Harger would
more carefully and patiently consider the objection the
speaker had raised to the proposed diminution of
oxygen, it would be found that there was no conflict
with the view of experts that a diminished weight of
oxygen could be safely breathed at each inhalation.
What the speaker contended was that mere short
periods of experiment were not sufficient to satisfy him—
and would not be sufficient to satisfy the miners of this
country—that an entirely new composition of air con-
taining 25 per cent. (£.e., 66 to 82J) more nitrogen, could
be breathed for many hours daily without injury, in the
long run, to health.

In answer to Prof. Louis, he said it was to be observed
that while there were, undoubtedly, different phases of
combustion in a colliery explosion, none could be carried
right outside of that term. The inflammatory or initial
phase was chiefly distinguished by the burning of the
volatile compounds and the more violent phases by the
burning of the coaldust in its complete state with its
carbon.

He could not quite follow the analogy drawn by
Prof. Bedson between the effect of oxygen on phos-
phorescence and on coaldust. Other considerations
seemed to require to be brought in. Anyhow, the fact
remained that the greater the density of air when mixed
with coaldust the greater the violence, while, with air in
a liquid form, coaldust would act as an ordinary
explosive under the blow of a detonator.

Mr. Blair must, of course, take the remarks about the
subsequent removal of stonedust by vacuum cleaners in
a commonsense way. Naturally, there might arrive a
time when the total amount of dust in places might
become so thick upon the floor as to be a nuisance, and
have to be removed in the usual manner. In case of
doubt, the way to settle whether the mixture had
become dangerous would be by analysis or, perhaps, by
washing. Mr. Ford had, of course, found the heavier
-stonedust to be a better brush than the lighter flue-
dust, but the latter would act more quickly as a

indications that the Lower Damuda series existed
beneath. It was thus merely their depth and not the
want of definition that put that portion of the lower
series out of present calculation.

It was true that the burning of the better seams was
more in evidence than that of the inferior, but that might
well be because the better seams had been more exten;
sively worked. It might prove that the principal
eruption had been at the locality where the better seams
were now near the outcrop. The occurrence of trap in
Jherria was well worth scientific investigation on the
part of the mining community or of the Government.
Did it invade the rocks before or after the faulting or
tilting of the strata ? Was the damage to any extent
bounded by faults or did identical conditions at both
sides of the fault show that the dislocation occurred
subsequently ? With regard to boring, although the
author’s statement was correct, systematic boring of the
field would, to some extent, elucidate its condition.

As to the quantity of coal raised and the available
supply, the author’s figures could not be regarded as
more than a very rough approximation. Coalowners
had been under the temptation to return as much of
their coal as possible as being the produce of the seam
most in favour. The analyses given might accurately
represent individual small selected samples, but did not
represent averages of the quality of coal as put on the
market, nor did they give a correct idea of the respec-
tive comparative value of the different coals from the
coal users’ point of view.

Amongst the problems to be solved were the origin of
the water which was giving so much trouble and the
housing and supply of labour.

Mr. G. H. Greenwell, replying, said it must be
remembered that the East Indian Railway, by its entry
into the Jherria coalfield in 1894, whether under com-
pulsion or not, initiated the opening out of that field.
The words “ taken up ” were correctly interpreted as
meaning that the underground rights in the area named
had been taken up, without inferring that the whole of
the area had been worked or was workable. Whilst
boring to prove the value of the coal in any small area
was practically useless, systematic boring of the whole
or large portions of the field would give information of
enormous value. That could only be done by the
Government or by concerted action on the part of the
whole of those interested. The origin of the water to
which Sir Ralph Ashton and Mr. Allan Greenwell had
referred was of Considerable importance. It was
suggested that the whole of the coal measures were
waterlogged and the water held in on all sides by the
impervious metamorphic strata, the only outlet being by 1
the Damuda River, which broke through in the south-
eastern corner of the field. If the theory were correct,
no considerable reduction of the quantity of water to be
dealt with could be expected in fresh sinkings, although
each shaft sunk to the dip would relieve those to the
rise of it.

The meeting then ended.

It is stated that sinking operations at the new Barnburgh
Colliery, the enterprise of the Manvers Main Company,
have been retarded owing to water having been encountered
in a considerable volume, and a complete pumping plant is
being installed.

Early Mining Records in Somerset.—Mr. F. Blacker, of
the Marble Works, Glutton, sends some interesting details
of the working of the coal pits at Clutton 300 years, ago to
the Somerset Guardian. In a report of the year 1610, the
Surveyor at Clutton at that time writes:—“There be
now three pits near Widow Blacker’s house; the
highest about 4 fathoms; the middle 6 fathoms; the
lowest 8 fathoms deep. At these depths they cut
out their lanes about 4 ft. high and broad. They
need no great store of timber-work for support. The lane
we crept through was a good quoits’ cast in length, wherein
we found but two cross lanes, whereby it may appear that
the mine is yet but newly entered into. They now work in
two pits at once, and have below two or three men and four
or five boys, and also three men to wind up the coal. At the
end of every lane a man worketh and there maketh his
bench, as they call it, and according to the vent they
make more or fewer benches. The wages allowed to the men
is to him that hath most 4s. the week, and to the boys Is. 6d.
Adding for candles, increase of wages for work by night,
ropes, sharpening of tools, baskets, &o., the whole week’s
charge may arise to «£3. Reckoning 100 horse loads a day at
3d., the receipt coming to £7 10a. the week, and the net gain is
£4 10s., of which one-fourth for the tenant, and the rest
remaineth for the lord.’’ This is an exact reproduction of an
old record, which Mr. Blacker has recently discovered. It
shows that the coalseams were being worked in Clutton
303 years ago. It is perhaps these old workings which have
been encountered in the development of the new colliery at
Clutton during the past year.