March 14, 1913.

THE COLLIERY GUARDIAN,

541

Nicholson desired that the process should be given a
prolonged trial in the quarry, under ordinary working
conditions. This trial will take place with as little
delay as possible.

The following are the results of the tests:—

Demonstration 1.—Hole (No. 1) 3 ft. 9 in. deep,
1J- in. diameter, 10 cartridges of gelignite, occupying
about 19 in. The last cartridge was inserted into the
hole with the patent apparatus, the spike having been
attached to the rod and passed through the cartridge,
Its point projecting (about 1 in.) and forced into the
ninth cartridge. The hole was then stemmed with
•marl to within about 4 in. of the top of the hole, and
the rod and spike withdrawn. The spike was then
detached from the rod and a No. 7 low-tension deto-
nator with covering “ P.P.” shield inserted through
the tube by means of the rod. The rod and the tube
were then withdrawn, and the top 4 in. of the hole
stemmed. The ends of the electric firing cable were
then attached in an ingenious manner to the leads of
the detonator. The shot was then ready for firing.
Instead of firing the detonator was safely withdrawn
by pulling on the cable.

Demonstration 2.—A new detonator was then
inserted in the same hole and the shot successfully
fired. The method of inserting the new detonator
was, first, to reinsert the tube and rod with the spike
attached, in the corehole so as clear it. The rod and
spike were then withdrawn and the detonator inserted
in the manner described above.

Demonstration 3.—Hole (No. 2) 3 ft. 9 in. deep, If in.
diameter, charged with eight cartridges of gelignite,
occupying about 15 in., in the manner described
above, and successfully fired.

Demonstration 4.—Hole (No. 3) 2 ft. 9 in. deep,
1| in. diameter, charged with five cartridges occupying
about 7 in., and the detonator withdrawn.

Demonstration 5.—Same hole re-charged with a
mew detonator, and again withdrawn.

Demonstration 6. —Same hole re-charged with a new
detonator, and successfully fired.

These demonstrations were followed by some illustra-
tions of holes lightly charged with Jib. of gelignite
and 2 lb. of black powder respectively, which were also
quite successful. In one case there was a mis-fire due
to an imperfect detonator, which exploded without firing
the shot. However, a new detonator was inserted and
the shot successfully fired. All detonators used were
covered with the “ P.P.” shields.

MIDLAND COUNTIES INSTITUTION OF
ENGINEERS.

Meeting at Nottingham.

A general meeting of the members of the Midland
-Counties Institution of Engineers was held at the
University College, Nottingham, the president, Mr.
W. H. Hepplewhite (H.M. inspector of mines), being
in the chair.

The election of the following was announced:—
Members : William Bardill, mechanical engineer, 6, St.
Peter’s-gate, Nottingham; Frederic Matthew Brown,
colliery manager, Mapperley Colliery, West Hallam
Derby ; George Rodgers Cowley, colliery manager,
Bond’s Main Colliery, Chesterfield; William Harvie
Gilchrist, colliery surveyor, Mapperley Colliery, near
Derby; Geoffrey Memertzhagen Jackson, Clay Cross
Hall, near Chesterfield; Henry Kirk, mechanical
-engineer, Burnbrae, Lismore-road, Sheffield ; D. Morgan,
mining engineer, 19, Melrose-avenue, Cricklewood,
London, N.W.; John Horridge Tasker, mechanical
-engineer, 72, Rupert-road, Sheffield ; John Henry
Whitaker, colliery director, Sunny Hill House, Nor-
manton, Derby. Associates: William Turner Bradley,
assistant deputy, 50, New Bolsover, near Chesterfield;
, Samuel John Clifford Needham, colliery deputy, Field
View, Greenwich, Ripley, Derbyshire. Students : Alfred
Grimes, surveyor, Oakdene, Walton-road, Chesterfield;
Thomas Hancock, mining pupil, Bagnall House, near
Nottingham; Harry Aspdin Hewitt, mining student,
21, Rosemary-street, Mansfield ; Fitz Donald Severn,
mining student, Denby Coal Company, The Ridings,
Ockbrook, Derby; Samuel Pestell Donald Thomson,
mining student, Groby Lodge, Groby, near Leicester.

Gob Fires.

The first paper for discussion was Dr. John Harger’s
on “Gob Fires and the Prevention of Gob Fires in
Mines.”

Mr. C. F. Jackson (Exhall Colliery, Bedworth) stated
that at that colliery they were working a 24 ft. seam of
coal which was subject to fires. They worked on the
system of longwall-retreating, so that the fires which
occurred in the goaf or waste did not cause the same
.anxiety as those which occurred in a mine worked on

over again. Subsidence was reduced to a minimum. In
one place, at a depth of from 200 to 300 yards, they took
out nine seams of coal under some big ironworks, and
there was no action on the surface. There was no time
for the roof to subside, because they kept moving up so
rapidly, and before the roof could settle the goaf was
stowed up solid.

The President remarked that if they once got the
earth on the move, neither water nor sand would stop it
until it solidified.

Miners’ Nystagmus.

The next paper for discussion was Dr. Lister
Llewellyn’s on the “ Illumination of the Coal Face,
with special reference to the incidence of Miners’
Nystagmus.”

Mr. Jackson said that they had had considerable
trouble with nystagmus at the Exhall Colliery, but,
instead of the badly-lighted stalls showing the biggest
percentage of cases, they had the biggest percentage
from the best stalls—best from the point of view of
lighting, of ventilation, and of making money. The last
point disposed of any suggestion of malingering, for the
men could make as much as 15s. per day, and there was,
therefore, every inducement for them not to feign
illness. He had formed an idea on the subject, and it
was this: The coal worked in those stalls was of a
slaty character, and broke with a conchoidal fracture,
showing millions of little facets which reflected the light.
The other seams were flatter and duller, and did not
show any brilliant reflections from the lamp. He had
come to the conclusion that the trouble to the eyes was
due to these facets, which flashed every time a man
moved—that was to say, every time he breathed. He
did not know whether Dr. Llewellyn had ever considered
that point, but he should be glad to have his opinion
upon it.

Mr. R. Laverick asked if the cases had increased
recently ?

Mr. Jackson replied that there had been an increase
in the cases during the last three years, and he believed
that that was the experience of most pits, though he
could not account for it. He was inclined to think that
it was partly epidemic and partly hereditary. Men
who had a squint or suffered from sore eyes were very
liable to nystagmus. In fact, men with any sort of
weakness of the eyes seemed especially prone to it.

Mr. P. J. Fenwick (Pleasley) said that they had a
candle pit in which men were affected with nystagmus.
He happened to be with Dr. Lister Llewellyn when he
visited Pleasley Colliery, and he afterwards wrote to him
on the question. Dr. Llewellyn suggested that the
colliers put their candles too far away from their holing,
and also recommended that the candles be shaded in
some way. It had occurred to him (the speaker) that
the cause might be found in the constant movement of
the candle flame in a heavy current of air. They all
knew how trying it was to the eyes to attempt to read,
or to do anything, by the aid of a flickering gas flame.

Mr. Nadin (Mansfield Woodhouse) said that they had
a naked-light pit and not a single claim in respect of
nystagmus. Dr. Llewellyn’s theory with regard to the
men at Pleasley was that they probably worked at a
safety lamp pit before going there.

Mr. Fenwick did not think that that was the case.
Most of the men had worked at Pleasley for many
years. Besides, the malady was not confined to men
working at the coal face. They had a deputy who was
incapacitated by nystagmus, and who had worked all
his life in this particular pit. He wondered if it had
ever been suggested that the disease might be caused by
a microbe ?

Mr. Nadin mentioned a case where a man was able to
cause the symptoms of nystagmus by making a par-
ticular movement of the head.

Mr. H. R. Watson (Codnor) said that all the cases of
nystagmus he had seen were in open-light pits, and, in
reference to a remark of Mr. Jackson’s, he might say
that one of the men had a squint.

Mr. Jackson observed that men with small eyes
seemed to be more subject to it than others.

Mr. Beckett said that he was glad to hear the theory
put forward by Mr. Jackson,* and it was well worth
investigation. It seemed to be borne out by his own
experience. The only cases of nystagmus they had were
in the Kilburn seam, which was bright and reflected the
light, while in the Tupton and Piper seams, which were
dull, they had not a single case.

This concluded the meeting.

the principle of longwall and packgates. Their chief
trouble was in the breaks at the sides of the main dips
and levels, and when they did occur they were almost
always in the near neighbourhood of doors, stoppings
and overcasts. It would be apparent that when wood
was present there was a greater liability to fire. They
had an official whose principal duty—almost his sole
duty—was to be on constant watch for signs of fire, and
the moment he found or received a report of any such
sign he got together a gang of men at once, and either
dug out or sealed off the place. They had water pipes,
with branches every 40 yards, laid on all the principal
roads, besides several lengths of fire-hose with instanta-
neous couplings, so that the most remote parts of the
workings could be promptly deluged with water. If he
had to open out a mine subject to gob fires and giving
off quantities of gas, he should seriously consider the
desirability of working on the longwall - retreating
system. At present he preferred not to express any
opinion on Dr. Harger’s suggestion to reduce the oxygen
in the atmosphere.

Mr. P. Beaumont (Church Gresley) did not think it
was possible to deprive the air of a certain amount of
oxygen throughout a pit for the purpose of dealing with
a gob fire, pure and simple. Mr. Dickinson, the manager
of the colliery next to his, had devised a plan somewhat
analogous in principle to that adopted in buildings
where they had the sprinkler system installed. Briefly
the idea was to introduce inert gas into the packs by
means of pipes, so arranged that when heating took
place the inert gas would be at once liberated. The
whole of the details had not yet been worked out, but it
seemed likely to be a success. He should like to ask
who started the bacterial theory of gob fires referred to
by Dr. Harger and to what extent had it been brought
up to date ? With regard to the experiments of
M. Fayol, which were quoted by Dr. Harger, his (the
speaker’s) experience did not support the conclusions.
One of these was that a heap of slack 7 ft. high never
fired. He had had heaps of slack 5 and 6 feet high which
had fired, and they had to insert pipes into it to liberate
some of the heat. He had one heap 12 ft. high of 4,000
to 5,000 tons, and that fired first of all on the top, about
the middle. It burnt its way downwards towards the
centre of the heap, then caved in, and finally the sides
gave way. They did not find those indications mentioned
by M. Fayol, though it was of course possible this might
be attributable to the nature of their coal. There was an
interesting point in Dr. Harger’s paper where it was
stated that under certain conditions coal had increased in
weight as much as 10 per cent. Perhaps that might
offer a very useful way of putting their tonnage up. At
one of their pits they had a water-gauge put through a
stopping, and they got by means of it indications of
pressure which were quite unnoticeable on an ordinary
barometer. There was no doubt, as Dr. Harger said,
that the atmosphere had a good deal of influence on
gob fires, and it was undoutedly the case that there was
much less trouble with gob fires or heating if they got
the roof pressure to take effect than there was where
the roof was held up by extremely good packing. He
was unable to accept Dr. Harger’s theory with regard to
the reversal of the air current. He knew of cases where,
if they did reverse the air, they would be doing some-
thing which they would not like to have on their
consciences. He failed to see how reversing the air
could make much difference to the question of dust, and
he doubted whether it would be of much practical value
in any other direction. He certainly should not like to
have anything to do with reversing the air in any of the
pits in South Derbyshire. In some quarters Dr.
Harger’s paper had been received with ridicule. But it
was the duty of mining engineers to take the paper and
see whether, and how far, they could work out in
practice the theoretical principles which Dr. Harger had
so clearly and so cleverly laid down.

The discussion was continued by Mr. Beckett, the
President, and others.

Hydraulic Stowing of Goaves.

In opening a discussion on Mr. Geo. Knox’s paper on
“ The Relations between Subsidence and Packing, with
Special Reference to the Hydraulic Stowing of Goaves.”
Mr. Beaumont said he should like to know how this
hydraulic stowing was going to be carried out in highly-
inclined seams. Coming up hill it would be all right,
but what about coming down hill ?

Mr. Beckett, who said that he had been in 20 collieries
where the system was successfully adopted, described
the plan in operation in the Camphausen Colliery in the
Saarbriicken coalfield. The water and sand were
brought down the shaft in pipes, and as by that means
they got a very big head, there was no trouble with the
pipes getting choked up. There was a level for collecting
the water, which was pumped into a sort of poundage in
the upper seam, and from there to the surface, to be used

Prof. Huntington presided on Tuesday night at the
fourth annual dinner of the Institute of Metals,
in London. The annual meetings were opened on the
same day, Prof. Huntington delivering his presidential
address.