348

THE COLLIERY GUARDIAN.

EebrttAry 14, 1913.

treatment, and cost to thfe ffiiner himself and the
industry generally, sink into the background. The
insistent problems connected with the medico-legal
aspect—age, duration of employment, ocular defects, the
personal factor, &c.—at present bulk very largely in
individual cases. In nystagmus, as in all occupation
neuroses, there is a weakening in the central controlling
mechanism of the brain, resulting in spasm and
inco-ordination, but before the accident of this break-
down occurs there must have been irregular strains on
the organ or muscles, which, in the case in point, are,
apparently, solely the strain on the sight due to defective
illumination. “ After all, man was not intended for
work underground, and Nature takes the revenge she
always demands.”

Dr. Llewellyn gives a carefully considered opinion on
the important practical point as to when (if at all) the
sufferer from incapacitating nystagmus should be
allowed to resume work underground. He holds that
no hard-and-fast line prohibiting such work should be
laid down. Many miners can return after surface work
for from three to 12 months. The views he expresses
as to exceptional cases and others ought to be of great
assistance to medical referees and county court judges.

BOOK NOTICES.

Miners’ Nystagmus: its Causes and Prevention. By T.

Listeb LlewelIyn, M.D., B.S. (Lond.), Tyndall
Research Mining Student of the Royal Society;
Medical Officer to the North Stafford Employers’
Insurance Limited. With a preface by Prof. J. S.
Haldane, F.R.S., and a Legal Appendix by
Douglas KnockeR, M.B. (Lond.), Barrister-at-
Law. Pp. xx. + 1^8- London: The “Colliery
Guardian” Company Limited. Price 6s. 3d. post
free.

This kind of monograph is of permanent value both
to the layman and physician. All the essentials (and
they are many) connected with the subject are clearly
and logically discussed, and the reader is helped by the
distinguishing type employed. With admirable self-
repression Dr. Llewellyn has so condensed the subject
matter that about 150 pages suffice to cover the ground.
The book includes 45 illustrations, which often, as in
those showing the positions assumed at the coal face,
and the varying degree of luminosity of different kinds
of lamps, are of more use than pages of description.
As the result of wide experience and research, the author
obviously has strong views, but the book gains by the

By John Harger, M.Sc. (Victoria), Ph.D. (Heidel-
berg). Newcastle-upon-Tyne: Andrew Reid and
Co. London: Longmans, Green and Co. 1913;
viii. + 184 pp. Price 3s. 6d. net.

In view of the papers recently read by Dr. Harger
I before branches of the Institution of Mining Engineers,

dispassionate and judicial attitude taken up throughout.; An account in detail of the procedure in all matters
He lets the reader see the divergencies of view and affecting nystagmus under the Workmen’s Compensa-
what can be said in support of each.	tion Act, 1906, and decisions in appeal cases, by

The amazing thing about miners’ nystagmus is the Mr. Douglas Knocker, is useful, and also the glossary
number of by-paths into which it leads. On the medical of the mining and medical terms used in the book.

side, account has to be taken especially of the mental Coai and the Prevention of Explosions and Fires in Mines,
state, and of accident, as influencing the onset as a cause (
of incapacity; on the physical side, of the conditions of ■
work underground—position, illumination and absorp-
tion of light by the coal surface; and on the economical
side, of the cost to the industry—estimated at £100,000 ;
yearly.	'

Those who knew the late Mr. Simeon Snell admired and the controversies to which they have given rise, the
him for the vigour with which he advanced his opinions; appearance of the present book will cause considerable
and his confident assumption that the position of the interest.

hewer necssitated an upward gaze in a more or less ’ The first five chapters are devoted to an account of
oblique direction, whereby fatigue was induced in the coal, combustion, and respiration ; and the later chapters
elevator muscles of the eyeball, to the neglect of other to mine explosions and fires, together with the means of
factors, has needed this thorough investigation for its dealing with them. It is in these later chapters that
refutation. We can see now that Snell’s line of enquiry, the theories held by the author are fully expounded, and
without intention on his part, was a prejudiced one. He various conclusions drawn which, if they were estab-
had formed his theory before apparently ever having ’ lished, would be of great practical importance.

seen the hewer at his actual work, and when he did he | jn the first place Dr. Harger propounds peculiar views
was blinded by his preconceived notions.	|	ag to the manner in which coaldust is deposited or raised

The most convincing facts which Dr. Llewellyn brings ! jnt0 the air in a mine road, and the conditions which
out to negative the myopathic theory are:—(1) The initiate a dust explosion. He believes that fine coal-
photographs showing that the hewer, the subject dust is deposited by the air current in such a manner
par excellence of nystagmus, has very rarely, except for that it is easily blown into the air by reversing (or even
the examination of the roof, to elevate the eyes ; (2) the ; by merely stopping!) the normal air current, but with
absence of the disease in metalliferous mines, because' difficulty by increasing it. Hence he explains the
naked lights are used, and because the walls reflect; (3) its j supposed fact that dust explosions always tend to travel
comparative rarity in naked light as compared with | against the air-current. He proceeds to recommend, as
safety-lamp pits ; (4) its great prevalence in the more ’ the first method for preventing dust explosions, reversal
badly-lighted mines ; and (5) the power of auto-! of the ventilation at week-ends,
suggestion in converting latent nystagmus into active
incapacitating disease.

The chapter on illumination receives the fullest
treatment, and numerous measurements, taken with
Trotter’s photometer, are given of the candle-power of
the different kinds of lamps and the surface brightness
—a term used to denote the amount of light reflected
from the coal surface, depending on two factors : (a) the
amount of incident light, which is variable; and (5) the
reflecting power, which is constant. The measurements
and illustrations are conclusive evidence, as Dr.
Llewellyn says, that the illumination at the face in
naked-light pits is generally five times as great as that
in the safety-lamp pits—the incidence of the disease in
the former is about one-sixth what it is in the latter,
having regard to the numbers employed, the frequency
in one large district varies inversely with the light
given by the lamps in individual collieries ; and lastly,
the amount of light falling on the coal face in a steam
coal pit is very small, and is often only one-seventieth of
a foot-candle. Practically all the light—from 86 to 97
per cent.—which falls on the coal surface is absorbed.

On the strength of this work of Dr. Llewellyn’s,
Dr. J. S. Haldane is optimistic enough to say (and he is
not wont to express himself unreflectingly) that when
the astounding deficiency of illumination is realised, in
a few years, if the knowledge acts as a stimulus to
introduce bettei* lamps, miners’ nystagmus will practi-
cally become a thing of the past. Romiee and Thibert
of Liege, indeed, have been able to show, from actual
examinations of several thousand miners, that since the
recent introduction of better methods of illumination,
especially the widely-used Wolf naphtha lamp, the
number of nystagmics has fallen from 41 per cent, prior
to 1891 to 18 per cent, in 1908-10.

In view of this dominant and fundamental fact, the
other sections of the book dealing with symptoms,

showing that certain kinds of dust, which can be ignited
by electric sparks when suspended in a glass tube
containing ordinary air or air to which a very little
oxygen has been added, cannot be ignited by sparks of
the same intensity when the oxygen percentage of the
air is reduced to 19 or 18 per cent., with 0’65 to 1*5 per
cent, of carbon dioxide added. From this much too
slender basis of fact he infers that coaldust cannot be
inflamed in a mine when the oxygen percentage is
correspondingly diminished, and that the reason why dust
explosions are commonly confined to haulage roads is
that there alone is the oxygen percentage sufficiently
high for a dust explosion.

Dr. Harger is doubtless quite correct in finding that
the lower the oxygen percentage, the less readily does a
mixture of dust and air explode; but he has brought
forward no evidence that the dusts which would not
explode with small sparks in air containing 19 or 18 per
cent, of oxygen would also not explode with a more
intense form of ignition, such as the flame of a gas explo-
sion or shot. It seems, also, almost unnecessary to point
out that the reason why dust explosions are commonly
confined to intake haulage roads is that coaldust
of sufficient fineness, dryness, and purity is commonly

present on these roads only. A return airway used for
haulage, and with sufficient dry and fine coaldust, will
propagate an explosion readily. As regards gas
explosions, Dr. Harger concludes that they cannot
occur when methane is added to air containing less than
17| per cent, of oxygen. He also quotes some experi-
ments to prove this, and dismisses as “ absurd ” the
results of previous experiments in which Afessrs.
Haldane and Atkinson obtained a very different result.
Those who have read the account of the latter experi-
ments will certainly not be convinced by Dr. Harger’s
statements.

On the basis of his theories with regard to the
influence of oxygen, Dr. Harger finally proposes to
render mines immune to explosions and gob fires by
adding purified furnace gas to the intake air, so as to
diminish the oxygen to the required extent. As ordinary
lamps would not burn, he recommends electric lamps,
with acetylene lamps for testing. To get rid of carbon
monoxide and excess of oxygen from the furnace gas,
he proposes careful regulation of the supply of fuel
(preferably gas or coaldust) and air, together with the
use of an apparatus which he calls the “ Equilibriator,”
for alternately removing any temporary excess of either
carbon monoxide or oxygen. How he proposes to
remove carbon monoxide, sulphur trioxide, &c., is not
clear. It is perhaps fortunate that the provisions of
the new Mines Act prevent any hasty application of this
proposal to an actual mine: for the risks of wholesale
carbon monoxide poisoning would, at the very best, be
most serious, and would probably far outweigh the
risk of explosions. The cost of purification, &c., would
probably also be very heavy. Dr. Harger does not seem
to have attempted to erect any experimental plant
capable of giving—even on the most modest scale—gas
suitable for the purpose. Until he has done this, and
furnished satisfactory evidence that any feasible diminu-
tion in the oxygen percentage of the air will be effective
in preventing explosions, mine managers are hardly

There is no doubt,”
he remarks (p. 119), “ that dust that cannot be removed
by reversal of the ventilation, as described, cannot be
put into the air by an ignition of firedamp or a blown-
out shot, and such reversal, done thoroughly in the
manner described, is the simplest method yet proposed
of rendering a pit safe from dust explosions.” If this likely to pay much attention to his proposals, particu-
method is the simplest, it is certainly also the most larly at a time when the stone dusting plan introduced
futile method ever proposed lor preventing colliery | by Mr. Garforth promises to furnish a practical and
explosions. We are tempted to ask whether Dr. Harger \ effective means of preventing dust explosions.

has ever observed any appreciable effect in removing ) Dr. Harger maintains that air containing a moderately
dust when the ventilation is reversed. There is certainly ; reduced oxygen percentage will be of great use in
no such effect, or it would have been noticed long before ; treating gob fires. There is, however, no evidence that
now. We must also remark that there is abundant. this plan would effectively check the extension of a gob
evidence that explosions travel either with or against' fire, although gas completely deprived of oxygen would
the air current, according to the position at which the , doubtless be useful in certain cases where it could be
initial ignition occurs, and the conditions in either practically applied.

direction with regard to fine and dry coaldust deposited
along the road.

Dr. Harger also lays great stress, as regards the
initiation of explosions, on the minute amounts of fine
coaldust normally present in mine air, and on the micro-
scopic amounts of oxygen and other gases contained in
this dust. In all this reasoning there is a total disregard
of the quantitative relations between effects and possible
causes. In view of his other opinions, it is not at all
surprising to find that Dr. Harger holds that the experi-
ments at Altofts, Lievin, and Eskmeals have been prac-'
tically useless.

A second leading idea running through the book is
that explosions and gob fires may be completely
prevented by a quite slight reduction in the oxygen
percentage of the air. Dr. Harger first points out that,
according to competent physiologists, the oxygen per-
centage of the air may be reduced from 20*9 to 17’5
without physiological inconvenience, and that at about
this percentage a candle or methane flame ceases to
burn. He further describes experiments of his own,

In the book there are collected a number of useful
i references to work by previous investigators. Unfor-
tunately, however, the author’s accounts of the work of
others are often most seriously coloured and distorted
by his own mental bias. Were it not for this, the book
would be of considerable value, apart altogether from
the theories contained in it. We regret that we cannot
say more for a book which, had it been written with
adequate knowledge and judgment, would certainly have
been extremely welcome.

I South Staffordshire and Warwickshire Institute of
Mining Engineers.—The next general meeting will be held
at the University, Edmund-street, Birmingham, on Monday
afternoon, February 17, at 3 p.m. The following important
paper “ On a Boring for Coal at Claverley, near Bridgnorth,
and its Bearing on the Extension Westward of the South
Staffordshire Coalfield” will be read by Dr. Walcot Gibson,
D So. The adjourned discussion of the paper on “ Mine
Rescue Appliances: a Danger Occurring in the Use of
Apparatus in which an Injector is Employed,” by Dr. J.
Cadman, D.Sc., will be continued.