556

THE COLLIERY GUARDIAN.

March 14, 1913.

Letters to the Editor.

The Editor is not responsible either for the statements
made, or the opinions expressed by correspondents.

All communications must be authenticated by the name
and address of the sender, whether for publication or
not. No notice can be taken of anonymous communi-
cations .

As 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.

REVIEW OF “ COAL AND THE PREVENTION
OF EXPLOSIONS AND FIRES IN MINES.”

Sib,—In your issue of March 7 Dr. Harger calls in
question some of the criticisms in the review of his book
on “ Coal and the Prevention of Explosions and Fires
in Mines.”

In the first place he endeavours to defend his theory
that coaldust is deposited along a mine road in such a
way that it cannot be readily raised except by stopping
or reversing the air-current, and that this explains the
“ fact ” that in a mine an explosion always tends to
travel against the air-current, although in the Altofts
experiments the explosion travelled just as readily with
the current. He goes so far as to assert that the
Altofts experiments “ are regarded by practical men as
little more than amusing firework displays—of little
scientific value, and of no practical importance what-
ever,” and that your reviewer, in questioning the “ fact ”
referred to, “ merely shows his ignorance of actual dust
explosions which have occurred in mines.”

There are now in existence a number of records of
colliery explosions in which the point of origin of each
explosion was accurately known. As typical instances,
the Albion explosion or the Seaham explosion may be
taken. These records show, without the shadow of a
doubt, that a colliery explosion travels both with and
against the air-current. In the Seaham explosion, where
the point of origin was close to the downcast shaft, the
explosion, over almost its whole extent, travelled with
the air-current. It is not your reviewer who displays
his ignorance of actual colliery explosions.

In the second place, Dr. Harger asserts that he has
evidence of the efficacy of reversal of the ventilation in
removing coaldust from mines. It is to be hoped that
he will take an early opportunity of producing this
evidence.

In the third place, he reiterates his belief in the
importance, as regards the initiation of explosions, of
the minute quantities of dust normally present in mine
air, and of the oxygen and other gases contained in this
dust. It may therefore be well to state, in somewhat
greater detail than in the review, the reasons against
Dr. Harger’s belief. Normal mine air contains so little
coaldust in suspension that it is possible to see for long
distances underground. On the other hand, it is well
known that coaldust is explosive only when present as
a dense cloud in air. Hence the quantity of dust nor-
mally present is only a minute and negligible fraction
of what is needed for an explosion. The oxygen con-
densed in dust from a mine amounts, according to the
determinations of Prof. Bedson, as quoted by Dr.
Harger on p. 17 of his book, to about 0’53 cubic
centimetres per 100 grammes of dust. On the other
hand, the quantity of oxygen required for the combustion
of 100 grammes of coaldust is about 170,000 cubic
centimetres. The oxygen condensed in the dust is thus
only about -32 ou o o what is needed to burn the dust,
and its influence on combustion is therefore negligible.
The rest of the condensed gas is, practically speaking,
only nitrogen and carbon dioxide, neither of which can
help combustion.

Dr. Harger, finally, complains of the criticisms of his
book, since its object was to lessen the number of lives
sacrificed by ignorance. This, however, was also the
object of the review; and Dr. Harger is so very
unsparing in his criticisms of others that he ought to
be the last to complain of criticism directed against his
own theories.	Your Reviewer.

March 10, 1913.

Sir,—I see, in your issue of March 7, that Dr.
Harger refers to a paper of mine about the “ Combus-
tion of Oxygen and Ooaldust in Mines ” written some
19 years ago, and quotes it as my opinion then that, if
proper experiments had to be done, the coaldust should
be deposited by the air-current.

Although he correctly quotes my words, he has failed
to quite convey the idea that was behind them.

I don’t know whether at that time Dr. Harger knew
anything, even chemically, about coaldust, but with me
at any rate it had been a study of a good few years from
the point of view of the mine “ explosion ” itself, and
most people were very, very sceptical that coaldust

would “explode” at all. Even we, who were convinced
that it would, believed that the difficulty of ignition was
great, and that it required a good many very rare
contributing coincidences.

In my anxiety, then, that any experiments which were
to be tried should not fail to produce “explosion ’’ for
want of providing every possible form of favourable
coincidence, I suggested that the coaldust should be
deposited by the air-current, and not in a more artificial
way.

This, however, was merely out of fear that coaldust
deposited in any other way should fail to ignite and
that, therefore, a false conclusion should encourage the
anti-coaldust men to continue to ignore the danger.

When, however, it was found possible to demonstrate
its danger in a quicker and more convenient way, there
was no reason why so much time should be wasted in
waiting for an air-current to make the deposit, even if
such a method was found to be reasonably practicable.

I am sorry I missed seeing in the Colliery Guardian
(and I have not now the number quoted at hand) the
criticism of Dr. Harger’s book, so I cannot say whether
he ought to feel aggrieved; but I have his book, and
think it merits his own description of being “ decent,
straightforward and readable.” It contains a great deal
of most interesting matter, but I am not surprised to
hear it has been severely criticised.

I hope students may read it, but I hope also they will
possess a good deal of discrimination.

Such a proposal as that of reversing the air-current to
clear the mine of dust is based upon an assumption and
not upon fact, and of course it is true that dust
explosions do travel against the air current, but it is not;
correct to infer that travelling with the current is
seldom. I am sorry that Dr. Harger has not had many
opportunities of seeing this for himself.

W. C. Blackett.

Acorn Close, Sacriston, Durham.

March 10, 1913.

TO OUR READERS.

[It has been pointed out to us that a sentence in
Dr. Harger’s letter, published in our issue of last
week, contains the suggestion that the review of
Dr. Harger’s book was written by Dr. Wheeler.
There is no foundation for this suggestion, which is
entirely erroneous.—Ed. C.G.~]

UNDEVELOPED LAND DUTY.

Sir,—Will you allow me, through the medium of
your columns, to draw the attention of manufacturers
and others to the importance of investigating the claims
which are now being made by the Commissioners of
Inland Revenue for Undeveloped Land Duty for the
years ending March 31, 1910, 1911, 1912 and 1913?
Several instances have come to my knowledge in which
these claims are being made upon the present owner of
land in respect of the duty accrued before his purchase,
as the Inland Revenue authorities contend that the
owner is liable in such circumstances under a provision
in section 19 of the Finance Act, 1910, that any unpaid
duty shall “ be recoverable from the owner of the land
for the time being.” The result, therefore, is that a
manufacturer who has recently purchased undeveloped
land for the purpose of extending his factory will find
himself called on to pay, perhaps, three years’ arrears
of duty, solely because the authorities did not assess
the duty in the year for which it was payable.

It is at the outset most important to ascertain whether
there is any liability for duty at all, because no such
liability exists where the land is used bona fide for any
business, trade or industry; and what constitutes such
a user must, particularly in the case of factories, give
rise to many complex pojnts of fact and law.

It is also important to ascertain whether, in the case
of land which was undeveloped at one time but which
has been gradually developed year by year, the proper
allowances have been made for the extent of this
development, with a corresponding reduction in the site
value of the land upon which the duty is assessed.

In a large number of cases these claims are being
made before the provisional valuations have been
finally settled, and although under such circumstances
the duty is payable, yet there is a specific provision in
the Act for an adjustment of the duties paid when the
provisional valuations are finally settled—a fact which
emphasises the importance of seeking expert advice
upon these provisional valuations.

My committee desire me particularly to point out how
important it is that these provisional valuations should
not be disregarded or treated as matters of no
importance, because when once they are settled there
is no means of redress in the future; and as there is also
the possibility that they may be used hereafter for the
purpose of the poor rate assessment as evidence of the

value of the land, buildings and machinery, the matter
becomes one of very great importance to the manu-
facturing community.

My committee will be very pleased to advise and
assist any manufacturers through the medium of their
experts if they will kindly communicate with me upon
the matter.	W. R. Buckingham, secretary.

The Machinery Users’ Association (Incorporated),

22 and 23, Laurence Poutney Lane,
Cannon-street, London, E.C.

March 8,1913.

THE STATUS OF MINE SURVEYORS.

(Corrected Copy of Letter which appeared in issue of
the 7th inst.)

Sir,—I shall be glad if you will allow me to thank
Mr. W. H. Galletly for the able explanation he has
given regarding the proposed mining branch of the
Surveyors’ Institution. His proposals seem to me to be
worth very careful consideration and, perhaps, when all
reasonable objections have been met, hearty support.

But I am not yet satisfied that the merits of the rival
proposals, viz.:—

1.	To arrange for a surveyors’ branch or branches
of the various institutions of mining engineers ; and

2.	To form an entirely independent institution of
mine surveyors,

have been fully examined.

The advantages of. being connected with the mining
engineers are very obvious, seeing that so large a
number of mine surveyors make managership their
ultimate aim. In particular, the literature issued
by the mining institutes is plainly more valuable
to the surveyor than that of the Surveyors’ Institution
from both engineering and valuing standpoints, as
witness the following samples of abbreviated titles of
papers taken systematically from the top of each eighth
page or thereabout of the index to the Transactions of
the Surveyors’ Institution, vols. i. to xlii., 1868-9 to
1909-10 inclusive:—

“ The Railways and the Farmers ”;

“ Compensation for Fruit Farming ” ;

“ Prevention of Corruption Act ”;

“ Valuation (Manurial Residues)

“ Romney Marsh, Past and Present ” ;

“ Trade Depression ” ;

“ Facilities to Workmen for Purchasing their
Dwellings.”

Or, to look at the matter in a slightly different way,
in the series of 42 volumes there are not many more
than half-a-dozen papers on surveying proper, and
they are mostly historical in nature.

I fancy that the mining institutes will be found to
have taken a far greater interest in the subject of
surveying than has the Surveyors’ Institution—at least,
if the number and character of their papers on the
subject are evidence.

Nor am I satisfied that the formation of an inde-
pendent association is impossible.

The German Institute of Mine Surveyors has only
about 350 members, but manages to bold a biennial
congress and to publish an invaluable quarterly; besides
this, its various branches hold local meetings.

The German Association of Assistant Mine Surveyors,
with about 160 members, is issuing its own monthly,
Der Markscheidergehiilfe.

Why cannot we do as well as our Continental
cousins ?	L. H. Cooke.

Royal School of Mines,

March 5, 1913.

Hull Coal Imports.—According to the official returns the
quantity of coal received into Hull during last month was
582,098 tons, of which 536,386 were by rail and 45,712 tons
were by river. The total in February 1912 was 506,608
tons. The total quantity imported during the first two
completed months of the present year was 1,225,384 tons, as
against 1,038,896 tons in the corresponding period of 1912.
The following are the collieries who chiefly contributed the
above figures :—Bentley, Carlton Main, Grimethorpe and
Frickley, Dalton Main, Denaby and Cadeby Main and
Manvers Main.

Hull Coal Exports.—The official return of the exports of
coal from Hull for the week ending Tuesday, March 4,
1913, is as follows: — Amsterdam, 1,501 tons; Abo, 399;
Antwerp, 827 ; Assens, 2,039; Bandholm, 1 282; Bruns-
buttel, 1,225; Bremen, 1,478; Copenhagen, 595; Christiania,
1,562 ; Drontheim, 219; Drammen, 610; Fredrikshaven, 54;
Ghent, 352; Gothenburg, 426; Harlingen, 899; Hamburg,
8,935; Harburg, 1,718; Iceland, 1,925; Kallundborg, 1,461;
Landscrona, 1,090; Libau, 300; Malmo, 1,550; Odense,
1,341; Oran, 910; Oxelosund, 3.921; Reval, 6,350 ; Riga,
2,540; Rotterdam, 7,026; Rouen, 6,118; Stettin, 3,179;
Tuborg, 1,471; total, 66,418 tons ; corresponding period last
year, 55,065 tons.