Apbil 24, 1914.

THE COLLIERY GUARDIAN.

899

prevent escape of the liquid whatever the position of the
lamp, whilst allowing the escape of gas generated by
chemical action in the accumulator.

(3.) A cast aluminium alloy hinged cover, forming a
flametight connection with the case, and secured thereto
by a riveted hasp and staple, locked by a lead rivet lock.

(4.) A bulb secured by a screw to a reflector which is
attached to the mouth of a cup-shaped recess on the
front of the battery case and with which it forms a
flametight connection enclosing the lamp contacts. The
bulb is protected by a stout glass and holder secured to
the battery case by screws.

(5.) A steel wire guard in front of the protecting glass,
secured to the battery case by screws and locked by a
lead rivet lock. The wire guard covers the screws securing
the protecting glass holder, so that in order to remove
the protecting glass and holder the wire guard must first
be removed.

(6.) A flametight screw switch in the cover, of either
of the types shown in fig. 8.

The lamp, which is to weigh not more than 4J lb., is
made at the works of Messrs. John Mills and Sons, at
Walkergate Brass Works, Newcastle-on-Tyne.

Varta Electric Safety Lamp, Type 2 Et. 4.

The Varta Electric Safety Lamp, Type 2 Et. 4, the
general design of which is shown in fig. 9, possesses the
following essential features:—

(1.) A sheet steel case stamped out of one piece,
enamelled outside; the front projecting piece, which

Fig. 9.—Varta Electric Safety Lamp, Type 2Et. 4.
(Vart Aecumulatoren Ges.

Fig. 10.—Wolf Rescue Lamp, No. 2.

(Wolf Safety Lamp Co.) -

contains the bulb, being of steel securely welded to the
case. The case has a steel lid hinged at the back and
locked in front by a lever catch and a lead rivet lock.
The lid forms a flametight connection with the case by
the use of a washer of indiarubber or other suitable
material.

(2.) An electric accumulator so constructed as to
prevent escape of the liquid whatever the position of the
lamp, whilst allowing the escape of gas generated by
chemical action.

(3.) A block of insulating material within the case to
which are fixed the contacts making connection with the
battery terminals. The front of the block carries the
bulb and a reflector.

(4.) A brass hinged shield protecting and holding in
position a stout protecting glass. The shield is secured
by a screw at the top, which is covered by a projection
on the locking lever, thus preventing the screw from
being tampered with when the lamp is locked.

The protecting glass forms a flametight connection
with the case by means of a washer of india-rubber or
other suitable material.

(5.) A flametight screw switch on the front of the
lamp held in position by a plate riveted to the case.

The lamp, which is to weigh not more than lb., is
made at the works of the Varta Aecumulatoren Gessell-
schaft, at Oberschoneweide, near Berlin, Germany.

The Wolf Rescue Lamp No. 2.

This lamp is a modification of the Wolf Electric
Lamp No. 2, and is identical with it in all but the
following respects:—

(1.) The bulb and reflector are contained in a hooded
shield of the type shown in fig. 10, furnished with a stout
protecting glass held in position by a screw ring locked
by a screw inserted from the inside of the cover.

The lamp, which is to weigh not more than 5j- lb., has
been made at the works of the Wolf Safety Lamp
Company, either at Zwickau, Saxony, or at Bank-street,
Sheffield.

Particulars of the approved oil safety lamps will
appear in succeeding issues of the Colliery Guardian.

SOUTH STAFFORDSHIRE AND WARWICKSHIRE
INSTITUTE OF MINING ENGINEERS.

A meeting of this institute was held at the University,
Birmingham, on the 20th inst., the President (Dr.
J. Cadman) in the chair.

The following gentlemen were elected as associate
members: Mr. R. M. Latham, Ipoh, Perak, F.M.S.;
Mr. C. M. Corbett, Ipoh, Perak, F.M.S As a student:
Mr. W. L. White, 15, Barrows-street, West Bromwich.

Proving the Western Boundary Fault at Holly Bank
Colliery.

The President then called upon Mr. N. Forrest to
read his paper:—“ A Description of the Proof of the
Western Boundary Fault at Holly Bank Colliery”
(see p. 895).

At the outset of the discussion that followed,

Mr. J. C. Forrest said the most important question
to decide was whether they should drive a drift or
whether they should sink a pit. But before they could
drive through the fault they had to cross an upthrow,
and when they got into the downthrow measures they
got into what was practically a marl-hole. Mr. Clark,
of Aldridge, who was present, was frequently consulted,
and he would like to acknowledge the value of his advice.
Mr. Clark agreed with him that the entry into a marl-hole
at 450 yards below the surface was a remarkable expe-
rience. The marls they found very much resembled
those in the Essington brickyard, and after they had
entered those measures they called in Mr. Stobbs, who
was a well-known geologist, who discovered certain
fossils. Mr. Stobbs argued from his standpoint as a
geologist that they might have to go 400 yards before
they reached the coal. However, they expected to
reach the coal at 350 yards, and on that they based
their plans for the position of the shaft. On the way
they met the salt water, and he had no idea, until he
had heard the analysis given in the present meeting,
that that water was quite so salty. Personally,
he could not sufficiently thank the geologists for the
accuracy with which they had calculated the position of
the coal measures, because if that view had turned out
to be seriously wrong it might have cost them a very
large amount of money. They employed compressed
air from the surface brought down in 10-in. pipes to the
bottom, and those pipes were conveyed in 20-ft. lengths.
In each section they had expansion joints. As a
matter of fact, the mechanical arrangements worked
most smoothly, and they never had the slightest
trouble with the job. In driving the drift they
practically were pressed by a time limit, and if
they exceeded that limit they were running a serious
risk, and, after consideration, they decided not to
incur that risk. Another important consideration was
that if they had adopted the drift they might have
had to drive through 1,400 yards of marl, which would
have been expensive and undesirable, while it was very
likely that they would not be able to finish properly.
Another plan proposed was to start at a point indicated
on the section and drive a dip lead 1 in 4 west. This
would have brought them into the salt water measures
or Silurians. Naturally, they decided not to run
that risk, and if they had carried the drift below the
coal they would have reached the point at which he was
convinced it would not have been safe to proceed. He
would impress upon them the great importance of those
considerations in any future experiment of the kind. It
was obvious that there was a great risk of salt water,
but they had been fortunate enough to avoid that, and
the dryness of the area was a remarkable feature.

With regard to the use of compressed air, he com-
menced with a decided preference for compressed air,
and if he had to go through a similar experience, he
should again stick to compressed air. The fact that
more and more restrictions were being imposed upon
the use of electricity, and the fact that the first cost
would have had to be over £10,000, were factors which
they were bound to consider, and they were very well
satisfied with compressed air. With regard to their
future plans, they intended to enlarge the column in
that pit, to duplicate the column, and then put in more
air reservoirs, and add to the pressure. He believed
there were great possibilities in the future with regard
to compressed air, especially in view of the high pressures
which were coming into use. He was proposing to draw
from the pit about 500 tons a day, which was as much
as they considered they would be able to Jdo with that

shaft and the means of disposal. The fact had not been
mentioned, but in the course of their sinking they had
proved not only the 8 ft. coal, but every other measure.
The 4 ft. was the lowest, and that was the Old Park
coal. Then there was the 8 ft. coal or Wyrley bottom
coal, and the Brooch coal, and the Robins coal, and the
7 ft. coal which was the upper measure.

It seemed to be a clean-cut fault, and he confessed that
at one point when he considered his position with his
knowledge of the geology and its possibilities he was
frightened ; but it was a very interesting thing for the
young geologist to consider whether there was any
relation as to the thickness of the listing with the throw
of a fault. Probably every fault had its own history,
and it seemed impossible to rig up any rule. It had not
been a very costly job, although at the present time he
was not in a position to tell them what the cost was.
Possibly at some future time he would be able to do so.

Mr. W. F. Clark said he would like to refer to the
very capable manner in which the whole work had been
carried through, while the rapidity of it was one of
the most striking features. He thought they would
all admit that, considering the great distance in-bye,
to sink a pit 14 ft. wide, and to timber it, brick it,
wall it at the rate of 8 yards a week was highly
creditable to those in charge of the operations. He
would like to refer to a matter that had not yet
been mentioned, and that was the great importance of
that sinking from the mining point of view, The work
had demonstrated the existence of the coal under the
western fault, and it had proved that the most valuable
seam in that direction lay at a depth at which it could be
worked economically. Having just been experimenting
in carrying on a similar proof over the eastern fault, he
could not help envying Mr. Forrest His success, and he
could only wish that the work in which he had been
personally associated had been equally successful. It
was really of great importance to know, before further
plant expenditure was incurred, whether the coal might
be depended upon to continue to lie consistently and
regularly. The operations that had now been carried on
were leading to a solution of the difficulty ; and it was
an excellent thing for the district that that proof had
been carried out in a bold manner, and he felt certain
that all those who had heard that paper would agree that
the work had been carried out not only successfully but
wisely.

Mr. G. M. Cockin said that he would like to ask
whether the Etruria marls, which were met with, as
described in Mr. Forrest’s paper, corresponded with the
drift clays which were met with at Aldridge. Did they
know whether that fault was increasing or diminishing
as it went north and what was the course of the fault ?
Was it running north-west, or north-east?

Mr. S. L. Thacker said he was not quite clear what
was actually the distance over which the power was
transmitted to carry out that sinking longitudinally.
Another thing he would like to know was how the
engineers proposed to deal with the haulage of the coal
now being won from the new sinking. Another point
on which he thought an explanation would be of interest
was as to whether any water was met with in the
sinking. Mention was made that water was met with in
the rock roading driven through the red measures, but
was any water met with in the sinking itself ? He took
it that the only lining used was brickwork. He would
also be obliged if Mr. Forrest would tell them to what
depth they sank in the red rock, how far they had to
deal with the red rocks, and what coal strata they
were in.

Mr. J. Brindley said he had had the privilege of
seeing the site and the whole of the plant used, and he
felt bound to admire Mr. Forrest’s pluck in sticking to
compressed air. As he (the speaker) had always said,
electricity was not the universal power, and at ’the
present time there was a tendency to check its career
in underground work in collieries. There were more
enquiries than ever for compressed-air plant. Mr.
Forrest, sen., had remarked that it was possible to use
compressed air at higher pressures, and so reduce the
size of the pipes required, and thus get greater economy
from the use of this power. It seemed a long period for
this opinion to be justified, but Mr. John Morrison,
when manager of the Lothian Collieries, in Scotland,
installed a system of compressed air in which the air
was compressed in stages and afterwards utilised in
stages, and in that way an economy was obtained equal
to that of electricity. In that way they could take up
heat as the air passed through the pipe, and the
economy was very great. To use air at high pressures
and exhaust it to the atmosphere was not economical,
but great economy would be obtained by using it in a
number of stages. Compressed air compared very
favourably in many points with electricity. Mr. Forrest
had spoken of pipes in 50-yard lengths. He (the
speaker) took it that they did not attempt to carry
50-yard lengths along the workings, but that the pipes
were taken down in lengths of 15 or 20 feet and screwed
together as they were passed along the roadway. As
one who was associated with the firm which had had the
honour of supplying a good deal of plant of one sort or
another in connection with that colliery’s operations, he
presumed it was not necessary for Mr. Forrest to mention
that it would not be anyone else’s.

Mr. L. E. P. Russ said that he would like to ask Mr.
Forrest a purely geological question respecting the
proving. He would like to know what area to the west
Mr. Forrest considered the Holly Bank and the Four
Ashes measures were proved. The speaker’s company
were going to put down a deep borehole in the Severn