860

THE COLLIERY GUARDIAN

April 23, 1915.

more collapsible and transportable form. The stowing
face is set off at a suitable distance, and a cross barrier
system put in. This face is flushed full, and allowed to
silt down. The sludge running out comes through an
outside clarifying system, and eventually is led away in
water troughs. As the mixed material must be brought
in in pipes, the same method can be applied in taking
the water out in pipes.

Unfortunately, in level seams the relative pressures
under which the two can be transported are different.
However, the same problem has already been tackled,
as, for instance, at the Ilsede Pits rolling mills, and at
some of the Franco-Belgian systems. At the former
place is a very large ironstone mine, the material coming
out of which is a very sludgy and slimy substance,
which can be sent back by ordinary low-pressure
hydraulic centrifugal pumps. It is a serious item when
the return of the material has to be handled by pumps,
but the writer refers to a consigning system whereby the
material is slightly filtered, and then transported back
in troughs. There are very few seams where the irregu-
larity of the seam is so slight that there is not a certain
amount of dip to be got for the water to return back to
the lower points.

From the data and general information which the
writer has collected, he is of opinion that there must be
something like 500,000 yds. of stowing pipe already in
use on the Continent. It must also be realised that the
system of hydraulic stowing is being extended to
eastern countries, such as China and Japan, India, and
Canada. In South Africa it is already extensively
developed, and as is shown by the excellent paper
recently communicated by Mr. B. C. Gullachsen.* It is
high time that, through one of the mining institutes, or
by combination with some of the large mine owners, the
thorough investigation of the subject was commenced in
connection with one of the British coalfields. The writer
respectfully submits that, in order to compete with the
gigantic schemes of the German Mining Board, a
national scheme under the guidance of, say, the Insti-
tution of Mining Engineers, those universities which are
interested in mining engineering, the Mining Board of
Wales, such men as have already had some experience
with this system, and those who are experts in
by-product recovery, should be formed with the object
of dealing with the question of the successful utilisa-
tion of our coal, the increase of the life of the coalfields,
and the utilisation of bastard coal to the last iota of
power in the form of gas, oil, toluol, or in whatever
form available.

The writer has previously hinted at the attitude of
Birmingham in connection with the exhaustion of its
local coal supply, and the means which could have
reasonably been taken to work the deeper seams without
loss; and when he states that he estimates that the life
of the coalfield in and around the Birmingham area can
be increased by 300 years by the adoption of hydraulic
stowing, he thinks that he has put forward a case for
thorough investigation, and earnestly hopes that the
South Staffordshire Institute will give the matter its
serious consideration.

MIDLAND COUNTIES INSTITUTION
OF ENGINEERS.

Meeting at Nottingham.

A general meeting of the members of the Midland
Counties Institution of Engineers was held last
Saturday in the Lecture Theatre of University College,
Nottingham, the President (Mr. G. S. Bragge, of
Moseley) being in the chair.

The Acting - Secretary (Mr. Percy W. Lewis)
announced the election of the following :—Associate
member: Mr. William Gath Watkins, M.I.Mech.E.,
manager, colliery and mining department, Messrs.
George Fletcher and Company Limited, Masson Works,
Derby. Associates : Mr. Aaron Lowe, under-manager,
Buxton-road, Whaley Bridge; Mr. William Wright,
under-manager, Watnall Colliery, Watnall, Notts.
Student : Mr. Thomas Albert Staley, surveyor, Coventry
Colliery, Keresley, near Coventry.

The Late Sir Charles Seely.

The President observed that, meeting as they were in
Nottingham, they had brought home to them the fact
that they had lost one of their oldest members in the
person of Col. Sir Charles Seely, Bart. Sir Charles was,
as a matter of fact, one of their original members, and
might therefore be regarded as one of the founders of
the institution. He was one of the few—of whom he
(the president) was another—who could go back to the
’seventies, and though Sir Charles had of late years not
been able to take a very active part in public life, he
was sure that they would not like the opportunity to
pass without placing on record the great regret with
which they had received the news of his death. He
concluded by moving a resolution expressing the feeling
of the members; and this was adopted unanimously,
and in silence.

Mr. T. G. Lees (Newstead) said that since their last
meeting one of the most highly-esteemed members of
their council, Major Walker, had had the misfortune to
lose one of his sons in the war. He moved a resolution
tendering him their condolence.

Mr. B. McLaren (Pye Hall) seconded the resolution,
which was supported by the President, who remarked
that Major Walker had the consolation of knowing that
his son had died for his country.

The resolution was adopted unanimously.

Support of the Roof in Longwall Working.

A discussion took place on two papers by Mr. W. H.
Hepplewhite—“ Substitutes for Wooden Supports of
the Roof in Longwall Working,” and ” The Action and
Control of Differently Constituted Coal Roofs.”

Trans. Inst. M.E., 1914, vol. xlviii., p. 122.

Mr. Hepplewhite, referring to the discussion at the
last meeting, said that with regard to the question
raised by Mr. Bramall as to the crushing of concrete
props, there was no doubt that they did crush, but they
did not fly about. They crumbled in the middle, but
they probably acted quite as well as a prop which had
begun to bend. There were many of them in use in
Warwickshire. Instead of putting in a small quantity
of rope, however, they were now putting in nearly a
whole rope. They were using props of from 7 ft. 6 in.
to 8ft., and were doing so almost exclusively in the
main roadways. They would stand a big pressure, but
it was desirable not to place them too near the side. He
thought, however, that by placing the rope in the
middle, instead of near to the corners, they would not
get such an effective reinforcement, and, after all, the
wire was the thing for keeping the prop together.
Special tops were also being made, so that the props
could be driven up easier and more tightly.

The President asked if any member present had had
any experience with English coppice wood. That had
been suggested as a possible source of supply, but he
had heard—though it was only hearsay-—that while it
might look all right, directly they got a pressure on to
it, it began to assume the most beautiful curves.

Mr. T. G. Lees said that at Newstead they had bought
a small lot of spruce and poplar, but they had not used
any of it for props. It had been sawn up into bars and
sleepers in order to save the foreign timber. Most of it
was full of knots, while foreign timber, such as they had
been in the habit of purchasing, was very straight, had
few knots, and only a small taper. He thought that
many people who had bought English timber discovered
that they had been taken in with it when they got it to
the pit.

The President referred to one of the reports on the
timber question which had just been issued. It did not
look, with all the vast quantities of timber on the other
side of the Atlantic, that they were likely to go into the
market with it. At any rate, the price would be higher
than they had been paying for Baltic timber.

Mr. J. Mein (South Normant on) remarked that he had
recently been reading a report, and what struck him
most forcibly was the effect which sap or moisture in
timber had upon its efficiency. He did not remember
the exact figures, but it seemed to be established that a
wet prop was a very inefficient prop, while a dry one
was worth something approaching twice the amount in
its resisting force. A prop which was saturated would
stand from 20 to 30 per cent, less punishment or
pressure than a prop which was a dry one.

The President observed that the report he had men-
tioned related to the prices and quantities of timber
available. With regard to price, one of the comparisons
was this—taking all the charges into account, the total
cost of a certain quantity of timber was 124s. 6d., while
the price for the same quantity of Baltic timber was
only 71s.

Mr. P. Beaumont (Church Gresley) said that he had
experienced the truth of what Mr. Mein had pointed
out. They bought about 25 tons of English timber—it
came from the South—and when they received it they
found that it was not merely wet, it was practically
soaked, and when they got it into the pit, they found
that it would not stand anything like the pressure which
they had successfully carried with Norwegian wood.
The knots, which were very numerous, seemed to be a
great source of weakness, for those props which stood
longest eventually gave way where the knots were
thickest. As a substitute for Norwegian timber, it was
out of the market altogether.

Mr. E. E. Bramall (Leicester) said that'during a
period of 30 years he had used larch for all important
props under bars, and it had answered very satisfac-
torily. He quite agreed with what Mr. Mein had said
about wet timber, but his experience had been that for
bar timber there was nothing which would touch larch.

Mr. Beaumont, reverting to the subject of concrete
props, said that it seemed to him that one of the prin-
ciples of mechanics was violated by putting the
reinforcement down the centre. He thought that an
improvement could be effected by making a sort of
framework, and putting the reinforcement within quite
a short distance of the outer edges, and that a better
result would be obtained in this way by wires much
smaller than a wire rope.

Mr. Hepplewhite agreed that if the reinforcement
were distributed equally about the sides of the prop
they would, as Mr. Beaumont had said, get a better
result. He spoke in his paper about steel tubular props,
and he had had several experiments made with them.
The one with the bell mouth was of no use—it canted,
over with very little weight upon it.

Mr. S. Evans (Creswell) expressed his disappoint-
ment that Mr. Hepplewhite had dismissed in so few
words in his paper the subject of steel props. He had
just mentioned the use of tubular props, of which he
(the speaker) had had some little experience — not
perhaps in the stalls, but on roadways. He was of
opinion that hollow props—he meant those without any-
thing inside them—were of very little use, except
perhaps where they wanted to conserve the area of their
roadway. With regard to the use of steel props—he
referred to those of the H section, which were in use at
some collieries—he was surprised that Mr. Hepplewhite
had not more to say in their favour. He (Mr. Evans)
had had some years’ experience in their use, and he
had been at the trouble of getting out some figures with
reference to them. They had had those props in use at
the Creswell Colliery for 18 years, and they still had
them in general use throughout the whole of the pit.
During those 18 years they had had something like
2,000 tons of props. Of course, some were lost through
the carelessness of the men. A prop would be laid on
the floor, and when they threw a lot of slack, into the
goaf they were apt to get buried unless somebody was
always on the spot to prevent it. Very few indeed of
the props actually got broken. Some of those which

had been in a good length of time did occasionally bend
up at the bottom, but that did not occur very frequently,
and when it did they took out the props and
straightened them. Out of something like 8,000 steel
props which they had in use, they did not, on an
average, have to straighten more than 20 or 30 a week.
These they straightened themselves at a cost of 6d.
each, and they were ready for use again. He had no
doubt that there were props in use to-day which they
had had for the whole 18 years that the colliery had
been working. He was going to say that they were in
as good a condition as ever, and that was substanti-
ally so, though they had been straightened and
re-straightened a few times. As he had said, they had
bought 2,000 tons in the 18 years, and they had now in
use about 400 tons, so that they had lost about 1,600
tons. Many of those, however, had been sent away as
scrap after they had got too short for use. Their total
loss was 10 per cent., or not quite 100 tons a year. Of
course, to-day steel props were more expensive than
they had been for some time, but he would be right in
calculating the monetary loss at about £660 per annum,
which worked out at not quite ^d. per ton. He did not
wish the members to understand that steel props were
used exclusively. They did use some timber, but it
was very little, and he thought they would admit that
the cost of using steel props was very moderate indeed.

The President : Do you straighten them cold?

Mr. Evans : No; we always heat them.

Mr. Hepplewhite admitted that he went only very
scantily into the question of steel girder props. His
reason was that he knew that they had been tried at a
great many places, and had been thrown out. Their
use at Creswell was very exceptional. They had at
Creswell probably one of the best roofs in the whole
world to suit such props. He could not say whether
the props were made for the pit, or the pit for the props,
but they did undoubtedly agree uncommonly well. At
another of the same company’s pits they started the
use of steel girder props, but they were all thrown out
for tapered props. If they had a strong stone roof, with
no great depression, the girder props would be all right,
and the cost undoubtedly small, but they would cer-
tainly not do in the Warwickshire mines. They had
been tried there, but had to be discarded. At one
colliery in Notts, where they were used, heavy foot lids
and top lids were provided, so that there was a fair
amount of timber to be crushed before the pressure got
on to the prop itself.

This closed the discussion.

Water Dams at Netherseal Colliery.

The discussion on Mr. C. Dickinson’s paper describ-
ing ” Wafer Dams in Coal at Netherseal Colliery,” was
resumed.

Mr. P. Beaumont said he should like to add his con-
gratulations to those which had already been offered to
Mr. Dickinson for his very interesting paper. In the
construction of the dams he had undoubtedly a very
difficult task, and one which there wras no time to think
over. It occurred to him (the speaker), however, that
a local tough clay, known as “ Tough Tommy ” or
“ Blue Billy,” puddled up to a proper consistency, would
have answered better than cement. It was used in one
of the dams, and he did not think that it was merely a
coincidence that this seemed .to stand better than the
others. He also suggested that flannel steeped in
pitch and placed upon the outside of the wall with the
puddled clay built up to it would have prevented some
of the leakage. The way, however, in which Mr.
Dickinson Went to work, without drawings, and with
only the pre-conceived idea of shutting back the water,
and the necessity of throwing to the winds all text-books,
entitled him to the heartiest congratulations on the
success of his operations.

Mr. Dickinson, in replying, said that with regard to
the use of clay, Mr. Beaumont was quite right. They
used it at No. 27, which was the far dam. It was,
however, the only clay they had available, and they used
it all there. If they had had more they would certainly
have used it on the face of the other dams. For more
than two years the dams had now been closed off. They
had no connection with them at the present time, and
he sincerely hoped that they never would have again.

Signal Indicators.

Two sets of signalling apparatus were on view—one
known as Adlington’s signal apparatus, and the other as
the B-well indicator.

Mr. R. Colin Snow (Mexboro’) described the former,
pointing out that two plain fingers—the large one black
and the small one red—travelled over the dial. The
red finger had only two positions — “ 0 ” and “ 3 ”
(men). The black finger moved from figure to figure as
the raps were given. Two pushes were required at each
signalling point—one painted black, on which all coal
winding rings were given; and the other painted red,
in which all rings, both cautionary and action, were
given in connection with the winding of men. Repeated
•signals would not accumulate, if from 1J to 2 seconds
elapsed between the signals. The instrument required
0-8 ampere at 12 volts for vigorous operation, and was
thus within the capacity of a small battery of cells.

Mr. J. Strachan (Sutton Colliery) said that the
B-well indicator was the patent of the enginewright at
that colliery. Its principal recommendation was that it
could be attached to existing bell wires. It was non-
accumulative. In the No. 1 design a visual illuminated
signal was given to enginemen and banksmen simul-
taneously. In the case or box they could have as many
lines of signals as they desired. In the example before
them there were nine, and each line was illuminated,
as required, by two 8-volt 6-candle power lamps, the
current from which could be obtained from an accumu-
lator. The ‘“3” (for men), and “1” and ”2”
remained until cancelled by another signal, or by the
movement of the engines after compliance.

Mr. J. M. Whitehouse (Mansfield) said that the
apparatus had been much improved as the result of