May 31, 1918.

THE COLLIERY GUARDIAN.

1099

outer tube of rolled steel was fitted on this inner
portion so as to come into intimate contact at the
ends. This strongly reinforced the inner tube and
adequately provided for any tension strains, either
gradual or sudden, that might ensue. The taper of
each piece of prop introduced was so arranged that
a space of three or four inches was left between the
ends to allow for compression. A slot was provided
in the centre of the socket to permit the introduction
of a wedge for ejection purposes. If desired, a simple,
conical-shaped head could be fitted to the nose of each
part of the prop to facilitate ejection, although it
had been found that this was not altogether neces-
sary. The construction of the socket permitted of a
certain amount of resiliency, according to the pressure
exerted. The association of the three portions—the
socket and the two pieces of timber—provided abso-
lute rigidity. It was desirable that the outer ends
of the timber should be tapered, as they “ burred”
according to the pressure. The portions could be
used and re-tapered again and again.

Speaking of the advantages of the device, Mr.
Bingley said that the socket was practically in-
destructible. It permitted of highly economical use
of the timber, especially of timber salvaged from the
pit, and it also meant that short lengths of timber,
which were otherwise commercially useless, were use-
fully employed. The combination of socket and parts
made an absolutely rigid prop which was equally as
strong as the original, and it did not add appreciably
to the weight of the timber prop of the same length.
Irregular lengths of timber could be made use of
so long as the two parts, together with the socket,
made up the length required. Whatever the initial
cost of the socket might be, the capital expenditure
of an installation could be distributed over a term
of years. Another advantage was that the iron or
steel prop, with its undue weight, could be eliminated,
and the principal objection made by the men was thus
done away with. The combination could be used in
just the same way as the timber prop.

The President said that the question of pit timber
was a very serious one, and anything which could
be done to reduce the rate of consumption ought to
be well received. If by using up their short pieces
of timber they could bring down the consumption
they would have made an important contribution to
the prolongation of our timber supply.

Mr. W. Price Abell (Derby) said that the device
seemed to him to be simple, serviceable and practical,
and likely to help them temporarily over their timber
difficulties. The only two questions which suggested
themselves to him at the moment were: Would not
the steel sockets cost as much as, or more than, the
breakage of props? And did the introduction of the
socket impair the elasticity of the prop and render
it less adapted to the work it had to do?

Mr. Bingley, in reply to Mr. H. 0. Bishop and
Mr. R. Laverick, said that the tapering was done at the
pit bottom, and that the rougher the taper the better
it was. If more than one socket was used to a prop,
the prop would buckle unless they had sufficient taper.
A short taper would cause it to buckle.

Mr. H. E. Mitton said he could quite imagine that
at some collieries such a device would be most service-
able, but in his case they had seams which went down
to 2 ft. thick, and props wihch had been used in
the thicker seams and damaged were cut down for
use in the thinner seams. When that was possible
it seemed to be more economical than the adoption
of a device like the present. He had just been at
a meeting where the making of ferro-concrete props
was under consideration. The laboratory results of
these when compared with timber were very satis-
factory, but colliery managers who had used them
told a different tale. Such props were said to be
very difficult to withdraw, and the men damaged them
with hammers.

Mr. C. W. Phillips (Eastwood)) asked whether
there was any tendency to split, when the pressure
came on, at the point where the wood entered the
socket. Ferro-concrete he had found to be absolutely
unsatisfactory. Under a soft roof perhaps there was
not so much objection to it, but under a hard roof
the props split at the top, and when drawn they
could not prevent the colliers hitting them with a
hammer and so rendering them useless.

In reply to Mr. Percy, Mr. Bingley said that of
course the cost to-day was more than in normal times.
A 4 in. socket would cost about 8s.

Mr. W. H. Hepplewhite (Tamworth) thought that
Mr. Bingley’s device was likely to prove a very useful
one. He should like to know whether it was proposed
to use the props along the coal face or merely at gate
ends or similar places. He understood that the
pieces out of which the prop was made up were not
necessarily of equal length. When the prop was
properly set, was there any weakness where it was
likely to buckle?

Mr. Bingley said that it was proposed to use the
props along the whole of the coal face. Of course,
there was bound to be always a certain amount of
new timber, but there would be no distinction between
the new props and the old—they would be mixed
indiscriminately. As to buckling, no such tendency
had manifested itself. He found that there was no
difficulty in setting the props, and if the men would
knock them up at each end alternately there was abso-
lutely no spring in setting.

On the motion of the President, seconded by Mr.
Hepplewhite, a hearty vote of thanks was passed to
Mr. Bingley, who suitably acknowledged it, and added
that he would be prepared to work up the subject into
a paper, going fully into the question of cost and
everything else.

Tondu Colliery, Glamorganshire, which was closed 25
years ago, when 116 men perished in an explosion, is to
be re-opened.

On and after to-morrow (Saturday) the Foreign Trade
Department will be at Bridgewater House, Cleveland-
square, St. James’, S.W. 1.

SOUTH WALES INSTITUTE OF
ENGINEERS.

The ordinary general meeting of the South Wales
Institute of Engineers was held at Cardiff on May 24,
the President (Mr. J. Fox Tallis) in the chair.

The following were elected to the institute: As
members—Mr. J. F. Davies, Treharris; Mr. S. C.
Jones, Swansea; Mr. A. J. Joshua, Wh.S., Ponty-
pool-road, Mon.; Mr. W, H. Lewis, Cardiff. As
associates—Mr. W. O. Jordan, Blaina; Mr. J. M.
Thomas, Pontygraigwen, Pontypridd; Mr. J. Wil-
liams, Tonypandy. As students—W. A. Evans, Bridg-
end ; L. C. Harris, Aberkenfig; W. John, Pyle, Glam.;
B. Jones, Brynmawr.

The President announced that until further notice
the Proceedings of the institute would be published
half-yearly, instead of quarterly, on account of the
paper shortage.

“ Rheolaveur ” Coal Washer.

Dr. William Galloway submitted a short paper
describing the features of the Rheolaveur appliance for
washing small coal, compiled from an article contri-
buted by M. E. Dinoire, chief engineer of the Lens
Collieries, to the “ Bulletin de la Societe de 1’Industrie
Minerale,” published in 1915.*

In the ensuing discussion reference was made by
Dr. Galloway and the President to experiments that
are being conducted for the washing and utilisation
of small coal particles down to one-hundredth of an
inch, by Mr. J. M. Draper, Rhondda Engineering Com-
pany, Bridgend, who promised to furnish the institute
with the results of his work when he had completed
certain data.

On the question of maintaining pulsation in the
washing boxes, Mr. Hugh Bramwell spoke of a washer
in extensive use where the pulsation was maintained
by means of compressed air, and said he was not sure
that in the matter of simplicity this device was not
superior to the Rheolaveur type.—Dr. Galloway stated
the advantage of the latter lay in the large quantities
of coal with which it could deal and to do which by
any other method would entail a much more expensive
apparatus than the Rheolaveurs, which, according to
the paper, could each do from 50 to 60 tons per hour.
The cost of these troughs, with six Rheolaveurs in each
of them, was £3,817, allowing 10 per cent, for con-
tingencies and present prices. No other washer of
the pulsating type could be put up for twice or thrice
that amount.

A cordial vote of thanks was accorded Dr. Gallo-
way for bringing up the subject.

Gas-Firing Boilers.

“ Some Notes on Gas-Firing Boilers,” by Mr. T. M.
Hunter (see p. 1097) were next considered.

Discussion.

Mr. Thomas Sugden, London, stated that the time
was probably not far distant when more scientific and
more economical methods of firing steam boilers would
be generally adopted, and possibly enforced. Whereas
a good deal might be done by means of a well-designed
burner, it was at the same time desirable to modify
the design and construction of the boilers themselves.
This, however, raised a very serious problem, as safety
must always be the first consideration. It was remark-
able to note that while steam pressures had been going
higher and higher, and also the number of steam
boilers in use was a constantly increasing quantity,
immunity from explosions had greatly increased, a
fact which stood to the credit of boiler makers and was
largely due to the better material used, improved
methods of construction and design, and also to the
ever-increasing vigilance of the boiler insurance com-
panies. Progress in boiler construction had of neces-
sity been slow, and therefore any departure from well
known and approved lines would also be gradual. So
far, boiler construction on the lines suggested by the
author had not been found advisable. Some years
ago Dr. Nicholson advocated improving construction
on similar lines; but it was then pointed out, for the
reasons referred to, that a 16 in. w.g. draught would
not succeed. This criticism proved quite correct, and
was equally applicable to the suggestions by the
author. The type of boiler suggested by Mr. Hunter,
which was in vogue some 30 years ago, i.e., the semi-
Lancashire and marine boiler, was not likely to be
a success, for reasons which prevented this design of
boiler being generally adopted, and it was now prac-
tically obsolete. Exception might be taken to the
author’s remarks that pre-heating air could only be
economically done by extracting heat from the gases
leaving the boiler. It was well worth robbing the
boiler in many cases in order to obtain a higher tem-
perature, and even in such instances it would be
recognised that the residual temperature of the gases
leaving the boiler would be reduced in consequence.
With respect to the type of burner referred to by
the author, in order to secure the best results it was
necessary to avoid low or variable pressures, other-
wise back-firing would take place. It was also neces-
sary to provide means for screening the boiler, so as
to avoid irregular admission of air in exposed places.
Unless some protection was afforded, the end of the
burner would soon be burnt off. Further, it was of
the utmost importance to ensure a regular air supply
flowing evenly around the gas-nozzle. With coke-
oven gases the control of air supply was not difficult,
but with blast furnace gases, owing to the variations
in pressure and purity of the gases, the problem was
a more difficult one. Mr. Hunter’s remarks respecting
the leakage in boiler flues were important.

Mr. R. James (School of Mines, Treforest) referred
to the difficulty of correctly proportioning and con-
trolling the air to ensure complete combustion, and
said it was largely due to this factor that the efficiency
of the boiler plant at many collieries was rarely above
50 per cent. In addition to this loss the engineer
using gas-fired boilers had to consider the effect of the
water vapour on the gas in reducing the efficiency of

* See Colliery Guardian, November 3, 1916, page 851.

combustion. The engineer who had a quantity of
industrial gas available for power production would
have to decide, in the first place, between the alter-
native methods of using this gas under boilers, generat-
ing steam to drive turbine or other plant, or its more
direct use in the cylinders of a gas engine. He (Mr.
James) submitted a diagram, by which he sought to
show that, taking the basis of a battery of ovens
coking 100 tons every 30 hours—average ovens being
charged once in 30 hours—the power available from
gas-fired boilers and turbines was 268 horse-power,
while the available power from gas engines was 436
horse-power, or nearly double. In face of these figures
they had to enquire into the objections against the
more general employment of the gas engine. The
first of these was the natural reluctance to change to a
comparatively new type of prime mover until it had
fully proved its reliability. The manufacturers of
gas engines quoted insurance figures to prove that
where gas engines were used for producing electrical
power, the reliability was equal to that of a steam
plant. Of course the average engineer was extremely
doubtful of this claim, his idea of reliability being
freedom from minor troubles, ability to take over-
load, etc. Again, they must bear in mind that the
steam turbine was certainly a most reliable and econo-
mical power-producer. The manufacturers of gas
engines were, however, rapidly cheapening produc-
tion and removing many minor troubles of gas engines
under all conditions. In deciding between the two
methods of generating power the question of capital
and working costs should be carefully investigated in
conjunction with local conditions. If success attended
the large number of experiments now being under-
taken to discover an efficient method of rapidly coking
coal at low pressure, a great impetus would be given
to the gas power movement. The surplus gas from the
distillation of the coal and the gas obtained from
gasifying the coke product in producers might pos-
sibly be used in gas-fired boilers, to generate the steam
for winding engines and mixed pressure turbines, or
otherwise used for generating electric power at large
central distributing stations.

The discussion was adjourned.

Mining Electrical Engineering Problems.

Mr. Chris Jones, M.I.E.E., president of the War-
wick and South Staffordshire branch of the Associa-
tion of Mining Electrical Engineers, submitted a
paper entitled 11 The Consideration of Items of Prac-
tical Importance in Connection with Mining Electrical
Engineering” (see p. 1094).

The President observed that the paper was a
valuable contribution, having regard to the conser-
vation of our resources and the fact that we should
have to depend in the future very much more upon
transmitted power. As the hour was late, he post-
poned the opening of the discussion until the next
meeting.

THE BY-PRODUCTS TRADE.

Tar Products. — Tar quotations are practically un-
changed, and the business which is passing is of the
usual character. Pitch is firm in London at 52s. 6d. to
55s. and 30s. east coast f.o.b. Considerable quantities
have been shipped from Westmorland works recently.
Hardly any of the other by-products have moved outside
last week’s prices. Solvent naphtha is steady.

Current Quotations.—Pitch: London, 52s. 6d. to 55s.;
east coast, 30s. f.o.b. Crude tar : London, 32s. 6d. to 35s.;
Midlands, 27s. to 29s.; North, 28s. to 30s. per ton ex
gas works. Benzol : London, 90 per cent. Is. Old., naked;
North, 104d. to ll|d., 50 per cent., Is. 4d. to Is. 5d.,
naked. Solvent naphtha : Naked, London, 90-190 per
cent., 4s.; North, 3s. 9d. : July-December, 3s. 74d. and
3s. 6d. respectively: 95-160 per cent, naked, London,
4s. 3d. to 4s. 6d.; North, 4s.: July-December, 3s. 10|d.
and 3s. 9d. respectively. Crude naphtha: Naked, 30 ner
cent.. 84d. to 84d. ; North, 64d. to 64d. Refined nanhtha-
lene, £30 to £32 10s.: salts. 100s. Toluol: Naked, London,
2s. 4d. ; North, 2s. 3d. Creosote : Naked, London, 4|d. ;
North. 4d. to 44d. (Government price 75s. per ton f.o.b.).
Carbolic acid : Crude, 60 per cent., east coast and west
coast, 3s. 4d. naked : crystals, 39-40, Is. 3d. Cresylic : %
Casks, 95 ner cent., 3s.'; 97-99 per cent.. 3s. 3d. to 3s. 6d.
ex works London and f.o.b. other ports. Anthracene:
40-45 A 4|d., 48-50 A 6d., B l|d. to 24d. Aniline oil,
Is. 2d., casks free; salts, Is. 2d., drums free.

THE TIN-PLATE TRADE.

Liverpool.

A big line of 28 by 20 was placed last week on Allied
account, and this has had a strengthening effect on the
market, most works asking the full official maximum
price, which, on the present cost of tin, stands at about
32s. 10^d. per basis box for cokes, net cash, f.o.t. at
works. Some makers can still do with orders, and to
secure same are willing to make concessions of 3d. to
6d? a box for favourable specifications. Wasters con-
tinue in good demand, and top official figures have to be
paid : 28 by 20 are exceeding scarce. Terne plates are
very slow of sale.

OBITUARY.

Mr. John Jobson, of Bedlington, who has died at the
age of 85 years, worked in the mines from boyhood until
he reached the age of 70 years. He was wont to claim
that never once in that long period did he “ sleep the
caller.”

Mr. John Athey, who died on Tuesdav at the age of 54
vears, had been secretary of the Coxlodge branch of the
Northumberland Miners’ Association for many years and
took a prominent part in the public life of the district.

The death has occurred at his residence, White House,
Hindley. Wigan, of Mr. Thomas Lonsdale Bryan, mining
engineer, at the age of 45 years. The deceased gentle-
man. who had been in failing health for some time, and
who formerly practised as mining engineer, was a member
of a well-known Wigan familv that had been associated
with the mining industry for two generations.

Mr. Walter Kingdom who emigrated from Willington,
co. Durham, to New Zealand 29 years ago, died at the
Antipodes at the age of 68 years. For 10 years he was
secretary of the Brancepeth A Pit Miners’ Lodge.