286

THE COLLIERY GUARDIAN.

August 9, 1918.

f which the needle is supported. A very much more
refined compass could be made if mine surveyors and
instrument makers would consult with each other more
frequently than is generally done.

The best way to take a bearing with the existing
instruments is—in the case of the round compass—to
take the bearing roughly with the loose needle, and
then set the vernier to this approximate reading. The
needle should now be set on the zero line, and the sights
turned on to the distant mark. The movement of the
two plates is thus reduced to a minimum, and helps to
secure accuracy.

This procedure should be repeated, say, three times,
and the mean reading—providing no large differences
are observed—taken as the correct one. In the case of
the trough compass or outside vernier dial, the needle
should be set to zero and the vernier also, the upper
clamp loosened, a sight taken to the mark, and the
vernier read.

W ith the vernier still at the same reading the needle
should again be set to zero, the sight repeated and the
vernier read. The whole procedure should be repeated
as often as may be thought necessary and the mean of
the final reading accepted as the correct one—again
provided no large discrepancy exists between the
difference of any two vernier readings.

The compass which the writer has used with con-
spicuous success is a plain miner’s dial, provided with
two spirit levels, a clamp and tangent screw. The
needle, which is about 6 in. long, has an aluminium
vernier, mounted on the north end, reading to single
minutes. A bearing can be taken as rapidly as an
ordinary loose-needle sight, and with considerable
precision. The writer has also found this instrument
useful for constructing a table to correct bearings taken
underground at a different time to surface bearings, by
simply clamping the instrument and reading the vernier
every hour.

Furthermore, by using this instrument only when
taking important bearings, its adjustments are main-
tained in good condition and the pivot of the needle is
kept sharp, ensuring a lively needle.

Attraction of the Needle by Iron or Electric Currents.

Attraction of the needle due to rails, etc., is easily
guarded against with a little care. The writer has
found that the easiest way is to remove a length of rails
on each side of the compass and gradually to take away
other rails or iron on both sides (the needle being set at
some even degree), and by moving the dial keep the
needle at the same reading until, finally, the removal of
more iron ceases to affect the needle. An extra length
of plates or a little more iron could then be removed as
an extra precaution.

With regard to attraction due to the magnetic lines of
force emanating from electric cables, it is not every
day that an important bearing is required, and it should
be arranged either to take such bearing at a time when
the cable is “ dead ” or the current cut off.

It has been stated that surveyors in other countries
are turning their backs on the magnetic meridian. This
is not so. In Germany, where this subject has been
thoroughly investigated, the orientation of the licensed
mine surveyor is checked by the Government surveyor
by means of an orientation instrument, which is
mounted on the transit axis of the theodolite. A deter-
mination of the azimuth can be speedily effected, and
it may be taken that the accuracy of such determination
is within one minute of arc—a result which is sufficient
for the orientation of surveys of the highest importance.
The Government issues to mine surveyors in the various
coal fields tables which enable them to correct bearings,
taken at any time of the day, to the mean position for
that day.

Investigations have also been carried on in Germany
V at various depths—the magnometer used being carefully
compared for some months with a standard surface
instrument, when it was found that the underground
variations corresponded with the surface instrument,
both as to time and amplitude of diunral variation.

The Government could do much to raise the standard
of mine surveying in this country by establishing
observatories in the various coal fields, and issuing the
results weekly to mine surveyors in the locality of the
observatories. At the same time, arrangements should
be made for sending in the local surveyors’ instruments
for comparison with the standard instrument to see if
its diurnal variation corresponded with that of the
standard instrument. Finally, surveyors should demand
a much more refined compass than has been up to the
present available. It is, however, useless to improve the
precision of surveying operations unless the present
absurdly low standard of examination for mine sur-
veyor is raised. Another important factor upon which
more light should be thrown is that of the shrinkage of
mine plans, and the methods adopted to counteract error
from such causes. This latter error is probably respon-
sible for the loss of thousands of tons of valuable coal.
Moreover, unless the error due to shrinkage is counter-
acted, plans will be rendered inaccurate to a greater
extent than that due to bad surveying.

“ Fuller ” Safety Lamps Approved.—The Home Secre-
tary has issued an Order approving of the “ Fuller ”
miner’s electric safety lamps in all mines to which the
Coal Mines Act, 1911, applies, subject to the conditions
specified in the schedule of the Order.

Spain’s Coal Crisis.—Though coal production in Spain
shows an increase from 4,838,412 tons in 1915 to 5,972,474
tons in 1917, there are still 2,000,000 tons wanting to
satisfy the national requirements. Imports fell from
2,504,000 tons in 1914 to 1,090,000 tons in 1917, whilst
the four first months of 1918 show a decline to 174,540 tons
from 536,020 tons in the corresponding months of 1917.
There does not seem much hope that the home production
will be raised to the point of making up the difference,
since confidential reports from the Spanish coal mining
concerns show that, without exception, the miners are
hewing less coal than before, though their wages have been
raised several times

PRACTICAL EXAMINATION FOR MINE
FOREMEN.*

By J. J. Bourxuin.

At the annual examinations for candidates for certi-
ficates of proficiency as mine foremen, assistant mine
foremen and firebosses on May 23 and 24 last, by the
examining board of the Seventeenth Bituminous Dis-
trict of Pennsylvania, the first day was devoted to the
usual written tests, and on the second day the candi-
dates assembled at the Experimental Mine of the
United States Bureau of Mines, near Bruceton, Pa.,
for an oral examination. Each candidate was required
to make a careful inspection of the mine and report
his observations, together with any recommendations
which he might have to offer to the examining board,
just as he would inspect and report on any mine where
he might be employed in the capacity for which he was
seeking a State certificate.

The superintendent of the experimental mine had
made special arrangements for the occasion, props
having been removed from some of the rooms, whilst
in others props were put up in a careless manner;
cars were taken into the mine and left standing in
rooms and alqng the main entry; pieces of brattice
material and rubbish were littered around the haulage
ways. When this work had been completed, there
were in all about 20 topics which the candidates were
supposed to report as violations of the State Mining
Laws, or as unsafe practices. Because of the unusual
purposes for which the mine had been developed, many
conditions are present which would not exist in
ordinary mining practice. Shelves on which coal dust
is distributed for making explosion tests project from
the ribs, and in some places shelves span the entry
and aircourse at a height of about five and a half feet;
bolts also project from timbers set in the ribs, and
there are numerous projections from the roof which
would be dangerous in an ordinary mine. No stop-
pings have been built in the break-throughs between
rooms and a piece of brattice cloth hung across the
main aircourse just in by the first left butt is the
only means employed for coursing the air from the
main intake through the first and second butt entries.

Some parts of the mine were very dry and dusty,
incombustible rock dust, such as is used in rock dust
barriers, etc., having been permitted to remain in
the main aircourse in order to present a dusty condi-
tion for the occasion of the examination. Several
tons of fine coal dust was also sent into the mine from
the outside and distributed along the main entry.
Only six rooms have been turned in the mine, and, as
previously mentioned, the timbering in these had pur-
posely been put in bad condition for the period of
the examination; No. 6 room, which had just been
turned off first left butt, was slightly ahead of the air
and in the neck of this room a miner was at work
taking down the draw slate, under which he had set
no posts as a protection to himself. Side clearance
along the track at different places was obstructed by
piles of lumber, posts, etc., to such an-extent that it
would have been exceedingly dangerous to workmen
meeting a trip of cars at such places. Several cars
were left standing on the main entry, thus retarding
ventilation.

A hole had been drilled at the face of first left butt,
and into this hole a dummy charge had been placed,
stemmed with coal dust and arranged with the wires
of an exploded electric detonator projecting from the
dummy charge. Here a miner was at work pretending
to be drilling out a missed shot, while close at hand
he had a large paper bag containing black powder, a
metallic case containing several sticks of permissible
explosive, and four or five electric detonators lying
on the case containing the permissible explosive. The
blasting materials were left in a careless manner close
to the working face. Accumulations of gas were
arranged inbye the last break-through near the face
of first left butt entry, at the face of the main entry,
and near the face of the right stub entry. Since
methane has never been encountered in the experi-
mental mine in any appreciable amounts, it was neces-
sary to adopt natural gas for use in the examination.
The only objection to this substitution for an examina-
tion of this character is the fact that candidates may
not rely entirely on their safety lamps for detecting the
presence of gas, but may depend more or less on the
sense of smell. The fan was operating as a blower
and at a speed of about 35 revolutions per minute.

Before the examination the district inspector made
a short, informal speech, impressing on the men the
responsibilities of the positions for which they were
seeking certificates of competency, with some good
advice on the proper attitude of the mine official
toward his men, and laying special emphasis on the
part that temperance plays in the winning of success
by mining men. The several men who had been depu-
tised as assistants to the examining board for the day
were then stationed at certain points or assigned to
given districts in the mine and instructed to render
whatever assistance they could to the men undergoing
the examination that would be proper on such an
occasion and to make every effort to eliminate delays.

The candidates were started into the mine at five
minute intervals, and each man was allowed an hour
to complete his examination, which was considered
ample time, as the mine is small and could be
thoroughly inspected by an experienced man in half
that time.

The candidates for certificates as foremen proved
themselves possessed of more keen powers of observa-
tion than the others. Few men of any class failed to
note the dusty condition of the mine, and many recom-
mended that it should be cleaned up and sprinkled.
Very few candidates endeavoured to distinguish be-
tween those sections containing quantities of dan-
gerous coal dust and other sections containing inert
shale dust. This fact was very satisfactory to those
conducting the examination, as it is not believed to
be possible to distinguish between a dangerous dusty

* Coal Trade Bulletin.

condition and a non-dangerous dusty condition by
any means other than a chemical analysis of the dust.
Practically all reports referred to the lack of clearance
along the tracks as a violation of the law.

The absence of shelter holes, improperly posted
rooms, absence of stoppings in break-throughs between
rooms, etc., were noted by the majority of the men,
but only five candidates noted that the room on first
left butt was turned ahead of the air, and nearly one-
half of the entire number of candidates failed to note
the need of a door on the main aircourse inbye the first
left butt. Those seeking certificates as foremen and
as assistant foremen seemed particularly alert to the
careless methods of the miners at work in six room
and at the face of the first left butt, and these miners
were ordered out of their places many times during
the day. However, while some candidates noted that
the miner in first left butt was not only drilling out
a missed shot, but also handling his supply of explo-
sives in a most careless manner at the face, many
failed to observe one or the other of these conditions,
and very few noted that the miner had used dry coal
dust for stemming.

The presence of gas was reported in various ways;
some simply stated that “gas was found” in certain
sections of the mine; others spoke of having found
“explosive gas,” “a dangerous quantity of gas,” “a
trace of gas,” or “ a small percentage of gas,” while
in still other reports it was stated that gas was found
at certain faces and that it tailed back a given dis-
tance from the face. One man reported having found
carbon-monoxide.

A lack of experience in the use of the anemometer
and in reading the water gauge was apparent in the
reports of several of the candidates, as might be illus-
trated by the fact that one man found nearly five
times as much air travelling in the return airway as
he had found in the intake, and the water gauge read-
ings varied from 0*3 to 1-35 in., although uniform
conditions were maintained throughout the period of
the examination. Reports regarding the speed of the
fan varied from 35 to 68 revolutions per minute. How-
ever, taking everything into consideration, the fact
that the men were in a mine with which they were
unfamiliar, that they were more or less pressed for
time and perhaps more or less unduly conscious at all
times that they were undergoing an examination of
their ability as mining men, they did exceedingly well,
and the board was greatly pleased with the results.

PETROLEUM PRODUCTION BILL.

The Petroleum Production (1918) Bill passed its
third reading in the House of Commons, on Tuesday,
after two slight alterations had been made. The Bill,
as passed, is reproduced below—

1.	No person other than a person acting on behalf
of his Majesty, or holding a licence under this Act for
the purpose, shall search or bore for or get petroleum
within the United Kingdom, and if any person gets
petroleum in the United Kingdom in contravention
of this provision, he shall forfeit to his Majesty a
sum equal to three times the value of any petroleum
gotten by him.

2.	—(1) The Minister of Munitions on behalf of his
Majesty may grant licences conferring authority to
search and bore for and get petroleum to such persons
and upon such terms and conditions as the Minister
of Munitions may think fit:

Provided that nothing in this Act shall be construed
as conferring on any person any right to enter on
or interfere with land for the purpose of searching or
boring for or getting petroleum which he does not
enjoy apart from this Act.

(2) Where any such licence is granted, a copy
thereof shall be laid before Parliament as soon as
may be after the grant thereof.

3.	For the purpose of ascertaining the geological
conformation and the position, direction, and dip of
strata, any officer of the Minister of Munitions shall
have the same rights as to the production and exami-
nation of plans and sections kept at a mine in pur-
suance of section twenty of the Coal Mines Act, 1911,
or section nineteen of the Metalliferous Mines Act,
1872, as are by those Acts conferred on inspectors,
and those sections shall apply accordingly.

4.	—(1) For the purposes of this Act the expression
“petroleum” means all petroleum and its relative
hydrocarbons (except coal and bituminous shales and
other stratified deposits from which oil can be ex-
tracted by distillation) and natural gas existing in
its natural condition in strata.

(2) His Majesty may by Order in Council transfer
to any Government Department or authority all or
any of the powers conferred by this Act on the Minister
of Munitions, and in such case references in this Act
to the Minister of Munitions shall, as respects the
powers so transferred, be construed as references to
such other Government Department or authority.

5.	—(1) Nothing in this Act shall prejudice the right
of any person who, at the passing of this Act, is using
any supply of natural gas for any commercial purpose
to continue to use the gas for that purpose.

(2) Nothing in this Act shall be construed as im-
posing any liability on any person where, in the course
of mining or other lawful operations, petroleum is
set free.

6.	This Act may be cited as the Petroleum (Pro-
duction) Act, 1918.

Owing to ill-health, Mr. F. Fowler has retired from the
board of the Sheepbridge Coal and Iron Company Limited,
after 44 years’ service as director, and is succeeded by his
nephew, Mr. R. W. Fowler. Lord Aberconway has
been elected chairman of the company.

The shipments from the Port of Middlesbrough last
month included 49,110 tons of pig iron—the largest quan-
tity shipped from the port in any one month since August
of last year—372 tons of manufactured iron, and 7,384 tons
of manufactured steel. The total shipments amounted
to 56,866 tons, as compared with 60,375 tons in June and
39,343 tons in May.