February 20, 1914.

THE COLLIERY GUARDIAN.

417

LETTERS TO THE EDITORS.

TheEditois are not responsible either for the gtatpmen is
made. or the opinions expressed by correspondents.

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and address of the sender, whether for publication or
not. No notice can be taken of anonymous communi-
cations.

Is replies to questions are only given by way of published
answers to correspondents, and not by letter, stamped
addressed envelopes are not required to be sent.

THE HOME OFFICE AND THE USE OF
STONEDUST.

Sir.—Had Mr. Hailwood referred to the reference
mentioned in the writer’s letter he would no doubt have
reconsidered writing his communication, for it quite
shows he is dabbling with a subject of which he knows
nothing.

In the reference mentioned, he will find tests made by
Government inspectors of dust floating in the atmosphere
of both mines and pottery factories, and from those
tests he will gather that the floating dust in the mine is
about twice as much as that which the pottery worker
is subject to; therefore, the comparison is more than
fair. Although there was only half as much floating
dust in the potters’ workrooms as is found in the mine,
regulations have been made and stringently enforced
within the last two years to compel the pottery owner's
to abate this dust. The Government inspector who
made the tests on the pot works said in his report:—
“ Visiting factories with the members of the Committee
it at once became obvious that, in many instances at least,
the amount of dust in the air could only be very small,
and that an apparatus of considerable delicacy was
necessary for its estimation.”

This does not read as if there were thick clouds about,
and the writer is prepared to express the opinion, based
upon practical observation, that there is insufficient dust
floating in the air in any clay-operatives’ workroom in
the Potteries to even affect ‘ the light of a Hailwood
safety lamp, but regulations are being enforced to reduce
the floating dust.

As the Home Secretary has promised that the dust to
be used shall be one that is harmless physiologically, we
can now only wait and see what will be suggested.

Mr. Hailwood speaks of the effect inert dust has in
stopping an explosion. The conclusions of Prof. H. B.
Dixon, published in your current issue, convey a rather
pessimistic opinion of the effect of inert dust. If Mr.
Hailwood will take very careful note of the first sentence
of those conclusions, and then go carefully through the
conditions of the experiments as given in the fourth and
fifth reports, there is no doubt he will gather that inert
dust is receiving a large amount of undue credit. It is
hoped that your columns will be open and used for a
reasonable and reasoned discussion on the reports and
the conclusions set forth by Prof. Dixon.

E. 0. Simcock.

Hanley, Staffordshire, February 17, 1914.

THE SENGHENYDD EXPLOSION ABO THE
BONNETED CLANNY SAFETY LAMP.

Sir,—The opening of the Government court of enquiry
into the cause of this explosion is just to hand.

A lamp-lighting station is under suspicion as the
point of ignition, and the electrical signal wires are also
under suspicion on the ground that they were insuffi-
ciently insulated. Well, even if this were all fact and
absolutely true, it must be obvious that the inspectors
of mines, whose duty it is to see that the Act of Parlia-
ment is properly observed, had seen these dangers, if
dangers they were, yet they had nothing to object to
until the explosion occurred. A colliery manager has to
take the blame of the mistakes of his officials, and in
like manner the Chief Inspector is responsible for the
mistakes of his staff; that being the case these men
ought to stand on the same basis as the colliery
manager.

On January 14 the Home Office approved the use of a
single-gauze bonneted Clanny safety lamp for use in
any mines and made this known to the world at large,
although this type of lamp has frequently been proved
to be the reverse of a safety lamp. The writer has on
many occasions during the last few years called atten-
tion to the fact that the bonneted Clanny safety lamp
is not a reliable safety lamp. This opinion has been
based on many years’ experience and the many actual
failures of perfectly sound safety lamps which have
proved incapable of holding the flame of firedamp when
exploded within them. Of all these he will only refer to one
—viz., the bonneted Clanny safety lamp, which passed
the flame through a single gauze at Messrs. Cory’s Pentre
Colliery, whilst a fireman was making a test for gas in
the ordinary way. After the occurrence the lamp was
carefully examined by a large number of persons, none

of whom could find a flaw in it. Why did it fail to hold
the flame ?

M. Marsaut proved that the safety of this type of
lamp depended entirely on the position in which it was
held, and that its most dangerous position was when
inclined, as is often done by a man making a test for
gas. M. Marsaut has also left us his record, that even
a double-gauze bonneted safety lamp is not absolutely
safe.

In this connection it may be asked why all the safety
lamps lately sent in to be tested by the Home Office
officials, have double gauzes ? If a single-gauze safety
lamp satisfies Jhe Home Office as a perfectly safe lamp
in a gaseous dusty mine, why increase the friction of
the entering air, and as a consequence reduce the
illuminating power of the lamp by adding another
gauze ? This point was exemplified at Morfa at the
time of the explosion there. Marsaut lamps had been
imported, and, because the lighting power was reduced
by the double gauze, the inside gauze was taken out.
The lamp continued to be called a Marsaut, but all the
same it was only a Clanny.

The writer ventures to assert, without any equivoca-
tion, that the Home Office officials are fully aware that
the so-called bonneted Clanny safety lamp is not a safety
lamp fit to be used in a gaseous dusty coalmine; and if
they are not aware of the fact, then they are wilfully
ignorant.

For this reason, if for no other, the want of apprecia-
tion of the daily or momentary danger attached to the
continued use of the bonneted Clanny safety lamp ought
to be one of the matters enquired into in connection
with the Senghenydd disaster. There is no more
likely cause of the Senghenydd explosion than that
either a collier or an official was making a test for gas,
when the flame of the exploding gas within the lamp
passed through the gauze and fired the whole mine. It is
popularly supposed that a safety lamp gauze must
become more than red hot before it will pass the flame ;
but this is not always the case, and there are times when
the flame goes straight through the gauze just as if
there were no gauze to hinder it.

There are thousands of bonneted safety lamps (over
332,000) in use in Great Britain which could be converted
into double-gauze safety lamps in one week’s time, at
little more than the cost of the inner gauze. The
Senghenydd disaster has given us a real warning, and
it remains to be seen whether or not the Home Office
will take any practical steps to increase the safety of
mines, or will waste time by applying to Parliament for
all sorts of increased restrictions.

There is a motto often seen in connection with coal-
mines in the United States of America, viz., “ Safety
First ” ; and therefore the writer will say in conclusion
that if he is wrong in any one particular of what he has
already stated, he is open to conviction of his error.

James Ashworth.

930, Drake-street, Vancouver, B.C.,
January 27, 1914.

FLAME v. ELECTRIC SAFETY LAMPS.

Sib,—We notice that David Bowen, Esq., in your last
issue, has drawn attention to an error in the drawing up
of the quotation from his report of May 4, 1911, on the
comparative condle-power of the Cremer lamp. We
must certainly admit that the second column of figures
giving the actual candle-power should not have been
given in the table of results above Mr. Bowen’s name,
and that it is a clerical error we would quote our former
letter in your issue of August 15 giving these details in
the correct manner.

These actual candle-powers are the results, of various
standard tests which can readily be verified, and we
think, if Mr. Bowen had considered the matter, before
rashly stating that the candle-power of the Cremer lamp
did not reach unity, he would have realised that by
simple deduction his own tests refuted such a statement,
for taking into consideration the standard candle-power
of, for instance, the Davy or Wolf lamps as given in
various text-books, by simple multiplication the same
figure of 1116-candle power will be obtained for our
lamp; and we would also quote the results of the
exhaustive tests carried out by Mr. Saint, of the
Armstrong College, Newcastle, and reported in the
Transactions of the Institution of Mining Engineers,
vol. xlv., part 2, p. 336, Table 18, where the average
candle-power of this lamp over 10 hours is given as
1’018-candle power, and, we might also add, we have the
authority of Mr. Saint for stating that the lamp used at
these tests was a Cremer lamp of our present type—i.e.,
the same as used in the tests made by Mr. Bowen.

R. Cremer, Director,
The Cremer Lamp and Engineering

32, York-place,	Company Limited.

Leeds, February 16, 1914.

Sir,—In reply to the question by “ Positive ” as to
whether the new lamp referred to by the writer has
passed the Government tests, I have pleasure in
informing your readers that this is so. In the letter
informing us of the success of the lamp, it is incidentally
stated that the candle-power of the lamp half-an-hour
after lighting same was 1*9, and at the end of 10 hours’
constant burning, and without any cleaning, it gave
1’75-candle power.

I have recently added, without inconvenience to the
lamp, an internal reflector, and this has again increased
the illumination. In the natural course of development
the fittings have been simplified as compared with the
first samples sent out, and in its present condition the
lamp entails no extra cleaning labour over and above
that of an ordinary double-gauze lamp. It will stand
far more “ jolting ” without being extinguished, and the
device does not add more than 2 oz. in weight. It is
excellent for the reading of gas caps ; low “ caps ” of
1 to 1| per cent, being comparatively distinct, and
“ caps ” above 2 per cent, are very distinct. Once the
lamp has got warm the light remains very steady
throughout the whole of the shift, and scarcely ever
requires touching with the pricker.

In a recent test the lamp was suspended from the pit
cage when descending an upcast shaft in which the air
travelled at a very great velocity, and when down the
mine it was placed in the doorway of a regulator which
was closed to within 7 in., the air travelling through at
an enormous velocity, no doubt from 2,000 to 3,000 feet
per minute, and in neither of these tests was the lamp
extinguished.

As regards the fears by “ One who Knows ” that
there will be a large breakage of glasses, our experience
with these has been such that we have confidence in
taking the whole risk and cost of the replacement of
these breakages at a fraction of a penny per lamp per
week.

Since writing my previous letter giving candle-powers
of electric lamps, we have continued the tests, taking
two absolutely new bulbs supplied by the makers, and
we find, after charging up the battery to its utmost
capacity and having everything in its best possible
condition, that these bulbs indicate that the makers’
statement is more than double the actzial candle-power
given by the bulbs.

With these and the previous facts contained in the
writer’s other letters before your readers, we trust they
will agree that we are justified invoicing the complaints
of colliery owners and colliers in regard to candle-
powers, &c.	E. A. Hailwood,

Manager for Ackroyd and Best Ltd.

Morley, near Leeds,

February 16,1914.

Sib,—I am much obliged to Mr. Hailwood for his
friendly overtures. I know he has recently taken out
a miner’s electric safety lamp patent, and probably he
will very soon be advocating electricity and progress.

I was fortunate last week in being at a colliery where
one of the latest of Mr. Hailwood’s internal glass
chimney flame lamps was on trial, and I was given the
opportunity of measuring the candle-power of this lamp
in comparison with an electric safety lamp, and
practically under equal conditions, both lamps being
at their best. The observations of the photometer I
purposely left to the manager of the colliery and three
of his assistants, and upon their judgment the electric
lamp gave 77 per cent, more light than the flame lamp.
The electric lamp was giving 1’4 British candle-power
and the flame lamp 0 79-candle power, and it was agreed
by the observers that, apart from the photometer test,
the electric lamp was giving the better illumination.

Mr. Hailwood’s flame lamp was too hot to hold by the
body, the temperature of which I have since ascertained
was about 140 degs. Fahr., and, of course, such heat
would be a very great objection in the mine. It appears
impossible to obtain increased light with the flame lamp
without unduly increasing the heat.

I also tested a good ordinary flame lamp, and this
gave 0‘46-candle power, so that Mr. Hailwood’s lamp
was giving more candle-power than an ordinary flame
lamp.

My photometer was accepted in both tests as accurate
and reliable.	Henry F. Joel.

72, Finsbury-pavement, Moorgate-street,

London, E.C., February 17, 1914.

At the annual meeting of the proprietors of the Great
Northern Railway Company on the 13 th inst., the Right
Hon. Lord Allerton (chairman of the company, presiding)
said the cost of coal had increased by .£85,000, and he
doubted very much whether the cost of coal would be less
during the current half-year, because the contracts were
still running at top prices.