332

THE COLLIERY GUARDIAN.

February 16, 1917.

FURTHER NOTES ON SAFETY

LAMPS.*

By Simon Tate.

After the explosions of firedamp at Jarrow and Felling
early in the 19th century, the public became alarmed,
excitement ran high, and public men of all grades
demanded that a remedy should be provided. Rewards
were offered for the best means of working collieries
where firedamp existed; the aid of the Government was
invoked; and eminent scientists voluntarily gave their
services in seeking to provide a safe means of lighting
which, whilst enabling the miner to follow his employ-
ment, would not ignite firedamp.

From the time firedamp became prevalent in dan-
gerous quantities in mining for coal, the question of
providing a safe light to work by had occupied the atten-
tion of the brightest intellects that graced the mining
profession; occurrence of explosions stimulated still
further the efforts of such men as Nicholas Wood, John
Buddle, George Stephenson, Sir Humphry Davy, Dr.
Clanny, and many others, with the result that in 1814
Dr. Clanny invented a lamp that burned in an. explosive
mixture without igniting the surrounding inflammable
atmosphere. This lamp, however, although considered
scientifically safe, was so complicated and cumbrous,
that it wais found to be impracticable for use as an
ordinary means of lighting for underground work; and
it was not until about 20 years later, probably about
the year 1837, that the “ Clianny ” lamp was produced.

■ In 1815 George Stephenson, ad that time colliery
engineer at Killingworth Colliery, invented a lamp; and
in the same year, practically at the same time, Sir
Humphry Davy also produced one. After many pre-
liminary trials and partial failures, it is recorded that
both inventors 'succeeded, independently of each other’s
efforts, in producing a safety lamp, and both lamps were
found to be safe when burning in an explosive
atmosphere.

Both George Stephenson’s “ Geordy ” and Sir
Humphry Davy’s “ Davy ” depended on the same prin-
ciple for their safety, namely, small apertures in a metal
plate, or the meshes of a closely-woven yire gauze,
which enclosed the flame of a lamp. These, whilst
admitting the passage of an inflammable mixture, did
not allow the flame to pass from the inside to. the out-
side atmosphere, and consequently it did not ignite the
surrounding firedamp. This was the governing prin-
ciple of safety lamps, and from that time onwards miners
have always had the means of having a. safe light when
they encountered firedamp.

These three inventions led to important developments
in the output from fiery collieries, and a change imme-
diately took place in the working of gaseous coal seams.
Where previously it had been found too risky to extract
the coal pillars (and in many deep pits large tracts of
small pillars have been left, and many of them lost for
ever), immediately the safety lamp was adopted efforts
were made to work off pillars, and millions of tons of
coal have been extracted which but for the safety lamp
would probably have been irrecoverably lost.

In 1815, and for some time afterwards, it was
evidently the prevailing idea that it was quite safe to
use the safety lamp continuously for lighting purposes
in atmospheres charged with firedamp, thus enabling
the colliers to follow their usual work even in the pre-
sence of considerable percentages of firedamp; in fact,
the idea was prevalent that the safety lamp had been
invented for the express purpose of working in explosive
atmospheres.

From information handed down, it appears that the
fullest advantage was taken of this ' property of the
safety lamp, and at some collieries they were deliber-
ately and habitually used in atmospheres charged with
firedamp. Even under such trying conditions, implicit
trust continued to be placed in the efficiency and
security of the lamps; in fact, they were often used
under such conditions that the gauzes of the lamps
became red hot, and the lamps had to be taken out into
the fresh air to be cooled. At some collieries boys were
employed for the purpose of changing the lamps when
they became too hot to handle.

Sir Humphry Davy, in writing to. Dr. Gray on New
Year’s Day, 1816, made the following statement:—

I have made very simple and economical lanterns, and
candle guards, which are not only absolutely safe, but which
give light by means of the firedamp, and which, while they
disarm this destructive agent, make it useful to the .miner.
. . . There has been no instance of an explosion occurring in
consequence of the use of the Davy lamp where it has been
properly used, i.e., neither inadvertently opened, the meshes
of the wire disturbed, so as to widen some of the apertures,
nor the tissue too long kept at a red heat. . . . The miners
sometimes actually work with the cage at a red heat for
hours together.

That this was not an isolated case is borne out by the
remarks in the inaugural address delivered by Mr.
Nicholas Wood, the first president of the institute, at
the meeting held on September 3, 1852, when he said
that—

The subject of safety lamps will, therefore, no doubt form
the subject of your early and anxious investigation, and no
part of the subject, will require more serious or careful atten-
tion . . . and the fact that thousands of those lamps are daily
used in an inflammable atmosphere, render this an enquiry
of vital importance to the safety of the miner.

This statement points to the possibility that of the
three types of lamps at this time extant, the “ Davy ”
must have been the one most generally used, as neither
the “ Geordy ” nor the “ Clanny ” would have con-
tinued to burn under the conditions mentioned by Mr.
Wood.

The Clanny Lamp.

From information that the writer has been able to
gather, he thinks that the Clanny, with the adoption of

* From a paper read before the North of England Insti-
tute of Mining and Mechanical Engineers.

the Davy gauze fixed above the glass cylinder, only
became a practical miner’s lamp some time between the
years 1837 and 1843; certainly in the year 1853 it was
the lamp regularly used at Wearmouth Colliery, then
the deepest pit in this country; for we find that at a
meeting of the institute held that year, Mr. (afterwards
Sir) George Elliot, who at the time was the viewer of
Wearmoutih Colliery, stated :—

I am, perhaps, unduly partial to the Clanny lamp,; but, at
the same time, as the subject is before-the meeting, I think
it but fair to state that I have worked with it for several
years—six or eight years. I have employed several hundreds
of them; and in no. case have I been made acquainted with
a single instance where the safety of the miner has been
imperilled by any accident to the glass. We have a large
increase of light from it.

As Mr. Elliot stated that he had used this lamp for
eight years, this meant that it had been used at that
colliery from about 1845. When one considers the pro-
bable condition of the colliery at this early period of its
history, when the very deepest coal working of virgin
seams of coal was practically just commencing, it is
almost certain that the manager of this colliery would
not have adopted the lamp so generally if he had not
previously satisfied himself of its absolute safety for such
conditions as would exist at his pit. The writer believes
that its use was continued at this colliery down to
within quite recent years.

It may therefore with confidence be assumed that the
period suggested (1837 to 1843) is more or less correct
as the date of the invention of the Clanny lamp as we
know it, namely, the lamp with the single glass cylinder
and with the Davy gauze above it.

In its early days, this lamp, owing to its having only
a single glass surrounding the flame, was looked upon
by many colliery viewers with great trepidation; and,
even in the writer’s time, at many collieries it was only
allowed to be used on the wagonways and in the whole
mine workings, its use in the broken mine, being strictly
prohibited. In fact, it was looked upon by many offi-
cials at fiery pits as occupying a position midway
between a safety lamp and a stable lantern, and, in
their opinion, was not to be compared with the Davy
and the Geordy lamps as a safe light for working in the
parte of a mine where firedamp was likely to be present.
Yet, notwithstanding all the obloquy cast upon it, the
Clanny possesses two important advantages—it gives a
much better light than either the Davy or the Geordy
lamp, and it has the property of becoming extinguished
much more quickly than the Davy lamp in an explosive
mixture or firedamp, a very important factor when the
lamp is used by inexperienced persons.

The late Mr. Stephen C. Crone, in his “ Observations
on Pillar Working in Northumberland and Durham
Collieries,” when speaking of the use of safety lamps
mentioned only the Davy and the Geordy lamps, and
never even hinted at the use of the Clanny lamp. The
following is an extract from his paper :—

It is the invariable custom in the North of England always
to. use the Davy lamp where the least danger is to be. appre-
hended in pillar working. It is used in the least dangerous
parts of Killing worth Colliery; but in. the dip and most
dangerous parts, no other but the ” Geordy,” or Stephen-
son’s safety lamp, is allowed to be used, as being the most
improved, and affording greater protection from, danger than
the Davy. The Davy safety lamp is undoubtedly safe under
ail ordinary circumstances of danger; but on extraordinary
occasions, where danger is constantly to be apprehended, I
prefer the “ Geordy.” I mention this from having observed,
in persons unaccustomed to the use of the “ Geordy,” a
species of objection, almost amounting to a prejudice, against
this safety lamp, difficult to account for, unless they are
ignorant of the principles and action of the lamp. As the
” Geordy ” is not so generally known and extensively used
as the Davy, I may here give a brief explanation of its action,
and why I prefer it as above stated. When introduced into
an explosive atmosphere, the light gently flames up, and is
immediately extinguished. The reason of this is, the flame
absorbs all the oxygen inside the glass cylinder placed within
the gauze, and the air cells at. the bottom, to admit air for
the support of the flame, being too small to allow a sufficient
quantity of oxygen to pass through for supporting a large
flame, it is necessarily and immediately extinguished, 'the
heated air passing upward preventing a supply from the
holed cap on the top. This is not the case with the Davy
safety lamp. Every orifice of the gauze being open for the
admission of oxygen from the surrounding air, a sufficient
quantity is admitted to support a large flame; and when
introduced into an explosive atmosphere, it flames up, and
continues burning with a large volume of flame as long as
any oxygen remains, so a.s to render the gauze red hot, if
the lamp is continued in such an atmosphere. In the ordi-
nary course of working it is not, however, allowed to remain
in such an atmosphere until it becomes red hot, the workmen
being ordered to remove it. I merely state this, contrasting
the value of the. two lamps in an explosive atmosphere, the
utter inability of the workman to remain at work, in the
dark, under such circumstances, with a “ Geordy ” lamp,
which he might be tempted to do with a. Davy.

The present writer considers that the Mueseler,
Marsaut, and other glass lamps of simitar construction
are only modifications of, and some of them improve-
ments on, the Clanny lamp.

One of the restriction's imposed by the Government in
the Coal Mines Act of 1911 was the fixing of a. standard
of lighting power for safety lamps; in consequence of
this, the Davy and Geordy lamps have been practically
abolished, and the principle enunciated in the quota-
tion, “ The stone which the builders rejected has become
the chief comer stone,” is very aptly portrayed in the
past and present position held by the Clanny type of
lamp, and in its adoption by the Government.

The Geordy Lamp.

At the first introduction of the safety lamp, this lamp
undoubtedly, was theoretically the safest of the three
classes of lamps, because, owing to the principle of its
construction, it became extinguished on coming into
contact with an explosive mixture. Unfortunately,
however, it gave out the Least efficient light of the three,

and for this reason its use has gradually become less and
less general. The property possessed by the lamp of
ceasing to burn in gas, although very good when the
lamp is in the hands of an ordinary workman, is never-
theless very inconvenient for officials. . This extreme
sensitiveness and its poor lighting qualities no doubt
caused it Ito sink into, comparative disuse even before
it was tabooed by Parliament.

The Davy Lamp.

From 1815 down to 1911 this lamp undoubtedly
occupied the premier position of usage over all other
safety lamps, and, the author thinks, deservedly so, for
of all oil-burning safety lamps, it was and is the most
convenient and dependable. He has used the Davy
lamp for over 50 years, and for the latter 30 years a
tin-can Davy lamp; and probably his experience, has
been as varied as it well could be, for he has at times
required a. lamp -to be used under as trying conditions as
any to which safety lamps can well be put in practice;
and in all circumstances, 'and at all times, it has proved
reliable. With it he has always felt that he had an
instrument or implement—a trusted friend—that would
never with fair treatment play him false. He con-
siders the prohibition of the use of the protected Davy
lamp a serious blunder.

It was at Monkwearmouth Colliery that the first
authentic failure of the Davy lamp was adjudged by a
coroner’s jury to have been the cause of an explosion
resulting in’the death of a miner, the verdict being that
the air inside of the lamp fired, and by a sudden jerk-
ing the flame came through the gauze, fired the gas,
and so caused the deceased’s death. This decision
caused considerable discussion at the time, and a com-
mittee of the institute was appointed to investigate the
matter, but the author has failed to find any report of
its findings.

It is a remarkable fact in the history of safety lamps
that the Davy lamp, which for nearly 100 years has held
the premier position in the opinion of miners and mining
engineers as being the best practical lamp for dangerous
and important work, should be suddenly prohibited, not-
withstanding that probably most mining engineers, if
called upon to explore dangerous workings ,where
noxious gas might be met with, would, if permitted,
prefer a protected Davy lamp to any other oil-burning
safety lamp.

While the glass lamp of the Clanny type undoubtedly
gives out a higher candle-power than either the Davy
or the Geordy, and has, when used by the ordinary
workman, the excellent property of becoming extin-
guished in an explosive mixture, yet, on the other hand,
it possesses certain inherent weaknesses which renders
it unsuitable for officials, such as, for example, the
following :—

(1)	It too readily becomes extinguished in the pre-
sence of firedamp or blackdamp. Even when testing
for firedamp the examiner may easily lose his light if
he finds the gas in greater proportions or “ quicker ”
than he anticipated.

(2)	It is too readily extinguished by the slightest
shock; even a false step is sufficient to extinguish the
light.

(3)	Having only a single glass between the flame and
the outside atmosphere, its security is ended if the
glass becomes broken. It is therefore unsuitable when
creeping through or over falls, and in such like dangerous
positions.

(4)	It is too heavy to carry for persons who travel all
their shift in low’ places, such as drivers, deputies, and
officials, all of whom are greatly inconvenienced by its
weight and cumbersomeness.

The weakness of the unprotected Davy lamp was well
known and appreciated by the late Mr. Nicholas Wood,
Mr. John Wales, Mr. John Daglish, and other mining
engineers, long before the Hetton experiments. When
the author first went as a boy into the pits, which were
at that time under the direct superintendence of Mr.
Daglish, many of the Davy lamps had their shields
fastened down with solder; and in order to avoid the
necessity of raising the shield, some of the lamps had
transparent shields made of either mica or horn, so as
not to obscure the light. The idea of protecting the
lamp by means of a transparent shield seems to have
been first publicly mentioned by one of the members of
the Select Committee of the House of Lords appointed
to “ enquire into the best means of preventing the
occurrence of dangerous accidents in coal mines.” When
the witness (Sir H. T. De La Beche) was speaking of
the possibility of a current of firedamp causing the flame
of the lamp to be communicated to the outside atmo-
sphere, he was asked : ” Might not that be obviated by
something transparent being put in front of it?”

The vulnerability of the Davy lamp in its unpro-
tected form when exposed to currents of explosive mix-
ture travelling at high velocities was definitely demon-
strated by the- committee appointed by the institute.
The committee made a series of experiments at the
Hetton Coal Company’s collieries during the period
1857 to 1870, and the author well remembers hearing
the expressions of consternation from the officials
at the failure of the trusted Davy lamp, and also
the recovery of their confidence when it was found that,
with the addition of the tin-can case, the Davy was
perfectly safe for all practical purposes. One experi-
ment was quoted with great gusto, to the effect that
whereas without the shield the explosive current blew
through the gauze and exploded the outside explosive
atmosphere, with the addition of the tin-cap case an
even higher current failed to explode it. The current
was increased until it forced the lamp out of the box
altogether; it was istill alight, and had not exploded
the surrounding atmosphere.

Testing for Firedamp.

Various restrictions and prohibit ions have from time
to time been placed on the continued use of the safety
lamp in gaseous mixtures, and in the Coal Mines Act