INVENTION OF THE "GEORDY" SAFETY-LAMP.
Explosions of fire-damp were unusually frequent in the coal mines of
Northumberland and Durham about the time when George Stephenson was
engaged in the construction of his first locomotives. These explosions
were often attended with fearful loss of life and dreadful suffering to
the workpeople. Killingworth Colliery was not free from such deplorable
calamities; and during the time that Stephenson was employed as a
brakesman at the West Moor, several "blasts" took place in the pit, by
which many workmen were scorched and killed, and the owners of the
colliery sustained heavy losses. One of the most serious of these
accidents occurred in 1806, not long after he had been appointed
brakesman, by which 10 persons were killed. Stephenson was working at
the mouth of the pit at the time, and the circumstances connected with
the accident made a deep impression on his mind.
Another explosion took place in the same pit in 1809, by which 12 persons
lost their lives. The blast did not reach the shaft as in the former
case; the unfortunate persons in the pit having been suffocated by the
after-damp. More calamitous still were the explosions which took place
in the neighbouring collieries; one of the worst being that of 1812, in
the Felling Pit, near Gateshead, by which no fewer than 90 men and boys
were suffocated or burnt to death. And a similar accident occurred in
the same pit in the year following, by which 22 persons perished.
It was natural that George Stephenson should devote his attention to the
causes of these deplorable accidents, and to the means by which they
might if possible be prevented. His daily occupation led him to think
much and deeply on the subject. As engine-wright of a colliery so
extensive as that of Killingworth, where there were nearly 160 miles of
gallery excavation, in which he personally superintended the working of
the inclined planes along which the coals were sent to the pit entrance,
he was necessarily very often underground, and brought face to face with
the dangers of fire-damp. From fissures in the roofs of the galleries,
carburetted hydrogen gas was constantly flowing; in some of the more
dangerous places it might be heard escaping from the crevices of the coal
with a hissing noise. Ventilation, firing, and all conceivable modes of
drawing out the foul air had been adopted, and the more dangerous parts
of the galleries were built up. Still the danger could not be wholly
prevented. The miners must necessarily guide their steps through the
extensive underground ways with lighted lamps or candles, the naked flame
of which, coming in contact with the inflammable air, daily exposed them
and their fellow-workers in the pit to the risk of death in one of its
most dreadful forms.
One day, in 1814, a workman hurried into Stephenson's cottage with the
startling information that the deepest main of the colliery was on fire!
He immediately hastened to the pit-head, about a hundred yards off,
whither the women and children of the colliery were running, with
wildness and terror depicted in every face. In a commanding voice
Stephenson ordered the engineman to lower him down the shaft in the
corve. There was peril, it might be death, before him, but he must go.
He was soon at the bottom, and in the midst of the men, who were
paralysed by the danger which threatened the lives of all in the pit.
Leaping from the corve on its touching the ground, he called out; "Are
there six men among you who have courage to follow me? If so, come, and
we will put the fire out." The Killingworth pitmen had the most perfect
confidence in their engine-wright, and they readily volunteered to follow
him.
[Picture: The Pit Head, West Moor]
Silence succeeded the frantic tumult of the previous minute, and the men
set to work with a will. In every mine, bricks, mortar, and tools enough
are at hand, and by Stephenson's direction the materials were forthwith
carried to the required spot, where, in a very short time a wall was
raised at the entrance to the main, he himself taking the most active
part in the work. The atmospheric air was by this means excluded, the
fire was extinguished, the people were saved from death, and the mine was
preserved.
This anecdote of Stephenson was related to the writer, near the
pit-mouth, by one of the men who had been present and helped to build up
the brick wall by which the fire was stayed, though several workmen were
suffocated. He related that, when down the pit some days after, seeking
out the dead bodies, the cause of the accident was the subject of
conversation, and Stephenson was asked, "Can nothing be done to prevent
such awful occurrences?" His reply was that he thought something might
be done. "Then," said the other, "the sooner you start the better; for
the price of coal-mining now is _pitmen's lives_."
Fifty years since, many of the best pits were so full of the inflammable
gas given forth by the coal, that they could not be worked without the
greatest danger; and for this reason some were altogether abandoned, The
rudest possible methods were adopted of producing light sufficient to
enable the pitmen to work by. The phosphorescence of decayed fish-skins
was tried; but this, though safe, was very inefficient. The most common
method employed was what was called a steel mill, the notched wheel of
which, being made to revolve against a flint, struck a succession of
sparks, which scarcely served to do more than make the darkness visible.
A boy carried the apparatus after the miner, working the wheel, and by
the imperfect light thus given forth he plied his dangerous trade.
Candles were only used in those parts of the pit where gas was not
abundant. Under this rude system not more than one-third of the coal
could be worked; and two-thirds were left.
What the workmen, not less than the coal-owners, eagerly desired was, a
lamp that should give forth sufficient light, without communicating flame
to the inflammable gas which accumulated in certain parts of the pit.
Something had already been attempted towards the invention of such a lamp
by Dr. Clanny, of Sunderland, who, in 1813, contrived an apparatus to
which he gave air from the mine through water, by means of bellows. This
lamp went out of itself in inflammable gas. It was found, however, too
unwieldy to be used by the miners for the purposes of their work, and did
not come into general use. A committee of gentlemen was formed to
investigate the causes of the explosions, and to devise, if possible,
some means of preventing them. At the invitation of that Committee, Sir
Humphry Davy, then in the full zenith of his reputation, was requested to
turn his attention to the subject. He accordingly visited the collieries
near Newcastle on the 24th of August, 1815; and on the 9th of November
following, he read before the Royal Society of London his celebrated
paper "On the Fire-Damp of Coal Mines, and on Methods of lighting the
Mine so as to prevent its explosion."
But a humbler though not less diligent and original thinker had been at
work before him, and had already practically solved the problem of the
Safety-Lamp. Stephenson was of course well aware of the anxiety which
prevailed in the colliery districts as to the invention of a lamp which
should give light enough for the miners to work by without exploding the
fire-damp. The painful incidents above described only served to quicken
his eagerness to master the difficulty.
For several years he had been engaged, in his own rude way, in making
experiments with the fire-damp in the Killingworth mine. The pitmen used
to expostulate with him on these occasions, believing his experiments to
be fraught with danger. One of the sinkers, observing him holding up
lighted candles to the windward of the "blower" or fissure from which the
inflammable gas escaped, entreated him to desist; but Stephenson's answer
was, that "he was busy with a plan by which he hoped to make his
experiments useful for preserving men's lives." On these occasions the
miners usually got out of the way before he lit the gas.
In 1815, although he was very much occupied with the business of the
collieries and the improvement of his locomotive engine, he was also
busily engaged in making experiments upon inflammable gas in the
Killingworth pit. According to the explanation afterwards given by him,
he imagined that if he could construct a lamp with a chimney so arranged
as to cause a strong current, it would not fire at the top of the
chimney; as the burnt air would ascend with such a velocity as to prevent
the inflammable air of the pit from descending towards the flame; and
such a lamp, he thought, might be taken into a dangerous atmosphere
without risk of exploding.
Such was Stephenson's theory when he proceeded to embody his idea of a
miner's safety-lamp in a practical form. In the month of August, 1815,
he requested his friend Nicholas Wood, the head viewer, to prepare a
drawing of a lamp according to the description which he gave him. After
several evenings' careful deliberations, the drawing was made, and shown
to several of the head men about the works.
Stephenson proceeded to order a lamp to be made by a Newcastle tinman,
according to his plan; and at the same time he directed a glass to be
made for the lamp at the Northumberland Glass House. Both were received
by him from the makers on the 21st October, and the lamp was taken to
Killingworth for the purpose of immediate experiment.
"I remember that evening as distinctly as if it had been but yesterday,"
said Robert Stephenson, describing the circumstances to the author in
1857: "Moodie came to our cottage about dusk, and asked, 'if father had
got back yet with the lamp?' 'No.' 'Then I'll wait till he comes,' said
Moodie, 'he can't be long now.' In about half-an-hour, in came my
father, his face all radiant. He had the lamp with him! It was at once
uncovered, and shown to Moodie. Then it was filled with oil, trimmed,
and lighted. All was ready, only the head viewer hadn't arrived. 'Run
over to Benton for Nichol, Robert,' said my father to me, 'and ask him to
come directly; say we're going down the pit to try the lamp.' By this
time it was quite dark; and off I ran to bring Nicholas Wood. His house
was at Benton, about a mile off. There was a short cut through the
Churchyard, but just as I was about to pass the wicket, I saw what I
thought was a white figure moving about amongst the grave-stones. I took
it for a ghost! My heart fluttered, and I was in a great fright, but to
Wood's house I must get, so I made the circuit of the Churchyard; and
when I got round to the other side I looked, and lo! the figure was still
there. But what do you think it was? Only the grave-digger, plying his
work at that late hour by the light of his lanthorn set upon one of the
gravestones! I found Wood at home, and in a few minutes he was mounted
and off to my father's. When I got back, I was told they had just
left--it was then about eleven--and gone down the shaft to try the lamp
in one of the most dangerous parts of the mine."
Arrived at the bottom of the shaft with the lamp, the party directed
their steps towards one of the foulest galleries in the pit, where the
explosive gas was issuing through a blower in the roof of the mine with a
loud hissing noise. By erecting some deal boarding round that part of
the gallery into which the gas was escaping, the air was made more foul
for the purpose of the experiment. After waiting about an hour, Moodie,
whose practical experience of fire-damp in pits was greater than that of
either Stephenson or Wood, was requested to go into the place which had
thus been made foul; and, having done so, he returned, and told them that
the smell of the air was such, that if a lighted candle were now
introduced, an explosion must inevitably take place. He cautioned
Stephenson as to the danger both to themselves and to the pit, if the gas
took fire. But Stephenson declared his confidence in the safety of his
lamp, and, having lit the wick, he boldly proceeded with it towards the
explosive air. The others, more timid and doubtful, hung back when they
came within hearing of the blower; and apprehensive of the danger, they
retired into a safe place, out of sight of the lamp, which gradually
disappeared with its bearer in the recesses of the mine. {95}
Advancing to the place of danger, and entering within the fouled air, his
lighted lamp in hand, Stephenson held it finally out, in the full current
of the blower, and within a few inches of its mouth. Thus exposed, the
flame of the lamp at first increased, then flickered, and then went out;
but there was no explosion of the gas. Returning to his companions, who
were still at a distance, he told them what had occurred. Having now
acquired somewhat more confidence, they advanced with him to a point from
which they could observe him repeat his experiment, but still at a safe
distance. They saw that when the lighted lamp was held within the
explosive mixture, there was a great flame; the lamp became almost full
of fire; and then it smothered out. Again returning to his companions,
he relighted the lamp, and repeated the experiment several times with the
same result. At length Wood and Moodie ventured to advance close to the
fouled part of the pit; and, in making some of the later trials, Mr. Wood
himself held up the lighted lamp to the blower.
Before leaving the pit, Stephenson expressed his opinion that by an
alteration of the lamp which he then contemplated, he could make it burn
better; this was by a change in the slide through which the air was
admitted into the lower part, under the flame. After making some
experiments on the air collected at the blower, by bladders which were
mounted with tubes of various diameters, he satisfied himself that, when
the tube was reduced to a certain diameter, the foul air would not pass
through; and he fashioned his slide accordingly, reducing the diameter of
the tube until he conceived it was quite safe. In about a fortnight the
experiments were repeated, in a place purposely made foul as before; on
this occasion a larger number of persons ventured to witness them, and
they again proved successful. The lamp was not yet, however, so
efficient as the inventor desired. It required, he observed, to be kept
very steady when burning in the inflammable gas, otherwise it was liable
to go out, in consequence, as he imagined, of the contact of the burnt
air (as he then called it), or azotic gas, which lodged round the
exterior of the flame. If the lamp was moved horizontally, the azote
came in contact with the flame and extinguished it. "It struck me," said
he, "that if I put more tubes in, I should discharge the poisonous matter
that hung round the flame, by admitting the air to its exterior part."
Although he had then no access to scientific books, nor intercourse with
scientific men, nor anything that could assist him in his investigation,
besides his own indefatigable spirit of inquiry, he contrived a rude
apparatus by which he tested the explosive properties of the gas and the
velocity of current (for this was the direction of his inquiries)
necessary to enable the explosive gas to pass through tubes of different
diameters. In making these experiments in his humble cottage at the West
Moor, Nicholas Wood and George's son Robert usually acted as his
assistants, and sometimes the gentlemen of the neighbourhood interested
in coal-mining attended as spectators.
These experiments were not performed without risk, for on one occasion
the experimenting party had nearly blown off the roof of the cottage.
One of these "blows up" was described by Stephenson himself before the
Committee on Accidents in Coal Mines, in 1835: "I made several
experiments," said he, "as to the velocity required in tubes of different
diameters, to prevent explosion from fire-damp. We made the mixtures in
all proportions of light carburetted hydrogen with atmospheric air in the
receiver, and we found by the experiments that when a current of the most
explosive mixture that we could make was forced up a tube 4/10 of an inch
in diameter, the necessary current was 9 inches in a second to prevent
its coming down that tube. These experiments were repeated several
times. We had two or three blows up in making the experiments, by the
flame getting down into the receiver, though we had a piece of very fine
wire-gauze put at the bottom of the pipe, between the receiver and the
pipe through which we were forcing the current. In one of these
experiments I was watching the flame in the tube, my son was taking the
vibrations of the pendulum of the clock, and Mr. Wood was attending to
give me the column of water as I called for it, to keep the current up to
a certain point. As I saw the flame descending in the tube I called for
more water, and Wood unfortunately turned the cock the wrong way, the
current ceased, the flame went down the tube, and all our implements were
blown to pieces, which at the time we were not very able to replace."
Stephenson followed up those experiments by others of a similar kind,
with the view of ascertaining whether ordinary flame would pass through
tubes of a small diameter and with this object he filed off the barrels
of several small keys. Placing these together, he held them
perpendicularly over a strong flame, and ascertained that it did not pass
upward. This was a further proof to him of the soundness of the course
he was pursuing.
In order to correct the defect of his first lamp he resolved to alter it
so as to admit the air to the flame by several tubes of reduced diameter,
instead of by a single tube. He inferred that a sufficient quantity of
air would thus be introduced into the lamp for the purposes of
combustion, while the smallness of the apertures would still prevent the
explosive gas passing downwards, at the same time that the "burnt air"
(the cause, in his opinion, of the lamp going out) would be more
effectually dislodged. He accordingly took the lamp to a tinman in
Newcastle, and had it altered so that the air was admitted by three small
tubes inserted in the bottom of the lamp, the openings of which were
placed on the outside of the burner, instead of having (as in the
original lamp) the one tube opening directly under the flame.
This second or altered lamp was tried in the Killingworth pit on the 4th
November, and was found to burn better than the first, and to be
perfectly safe. But as it did not yet come quite up to the inventor's
expectations, he proceeded to contrive a third lamp, in which he proposed
to surround the oil vessel with a number of capillary tubes. Then it
struck him, that if he cut off the middle of the tubes, or made holes in
metal plates, placed at a distance from each other, equal to the length
of the tubes, the air would get in better, and the effect in preventing
explosion would be the same.
He was encouraged to persevere in the completion of his safety-lamp by
the occurrence of several fatal accidents about this time in the
Killingworth pit. On the 9th November a boy was killed by a blast in the
_A_ pit, at the very place where Stephenson had made the experiments with
his first lamp; and, when told of the accident, he observed that if the
boy had been provided with his lamp, his life would have been saved. On
the 20th November he went over to Newcastle to order his third lamp from
a plumber in that town. The plumber referred him to his clerk, whom
Stephenson invited to join him at a neighbouring public-house, where they
might quietly talk over the matter, and finally settle the plan of the
new lamp. They adjourned to the "Newcastle Arms," near the present High
Level Bridge, where they had some ale, and a design of the lamp was drawn
in pencil upon a half-sheet of foolscap, with a rough specification
subjoined. The sketch, when shown to us by Robert Stephenson some years
since, still bore the marks of the ale. It was a very rude design, but
sufficient to work from. It was immediately placed in the hands of the
workmen, finished in the course of a few days, and experimentally tested
in the Killingworth pit like the previous lamps, on the 30th November.
At that time neither Stephenson nor Wood had heard of Sir Humphry Davy's
experiments nor of the lamp which that gentleman proposed to construct.
An angry controversy afterwards took place as to the respective merits of
George Stephenson and Sir Humphry Davy in respect of the invention of the
safety-lamp. A committee was formed on both sides, and the facts were
stated in various ways. It is perfectly clear, however, that Stephenson
had ascertained _the fact_ that flame will not pass through tubes of a
certain diameter--the principle on which the safety-lamp is
constructed--before Sir Humphry Davy had formed any definite idea on the
subject, or invented the model lamp afterwards exhibited by him before
the Royal Society. Stephenson had actually constructed a lamp on such a
principle, and proved its safety, before Sir Humphry had communicated his
views on the subject to any person; and by the time that the first public
intimation had been given of his discovery, Stephenson's second lamp had
been constructed and tested in like manner in the Killingworth pit. The
_first_ was tried on the 21st October, 1815; the _second_ was tried on
the 4th November; but it was not until the 9th November that Sir Humphry
Davy presented his first lamp to the public. And by the 30th of the same
month, as we have seen, Stephenson had constructed and tested his _third_
safety-lamp.
[Picture: Davy's and Stephenson's Safety Lamps]
Stephenson's theory of the "burnt air" and the "draught" was no doubt
wrong; but his lamp was right, and that was the great fact which mainly
concerned him. Torricelli did not know the rationale of his tube, nor
Otto Gurike that of his air-pump; yet no one thinks of denying them the
merit of their inventions on that account. The discoveries of Volta and
Galvani were in like manner independent of theory; the greatest
discoveries consisting in bringing to light certain grand facts, on which
theories are afterwards framed. Our inventor had been pursuing the
Baconian method, though he did not think of that, but of inventing a safe
lamp, which he knew could only be done through the process of repeated
experiment. He experimented upon the fire-damp at the blowers in the
mine, and also by means of the apparatus which was blown up in his
cottage, as above described by himself. By experiment he distinctly
ascertained that the explosion of fire-damp could not pass through small
tubes; and he also did what had not before been done by any inventor--he
constructed a lamp on this principle, and repeatedly proved its safety at
the risk of his life. At the same time, there is no doubt that it was to
Sir Humphry Davy that the merit belonged of having pointed out the true
law on which the safety-lamp is constructed.
The subject of this important invention excited so much interest in the
northern mining districts, and Stephenson's numerous friends considered
his lamp so completely successful--having stood the test of repeated
experiments--that they urged him to bring his invention before the
Philosophical and Literary Society of Newcastle, of whose apparatus he
had availed himself in the course of his experiments on fire-damp. After
much persuasion he consented, and a meeting was appointed for the purpose
of receiving his explanations, on the evening of the 5th December, 1815.
Stephenson was at that time so diffident in manner and unpractised in
speech, that he took with him his friend Nicholas Wood, to act as his
interpreter and expositor on the occasion. From eighty to a hundred of
the most intelligent members of the society were present at the meeting,
when Mr. Wood stood forward to expound the principles on which the lamp
had been formed, and to describe the details of its construction.
Several questions were put, to which Mr. Wood proceeded to give replies
to the best of his knowledge. But Stephenson, who up to that time had
stood behind Wood, screened from notice, observing that the explanations
given were not quite correct, could no longer control his reserve, and,
standing forward, he proceeded in his strong Northumbrian dialect, to
describe the lamp, down to its minutest details. He then produced
several bladders full of carburetted hydrogen, which he had collected
from the blowers in the Killingworth mine, and proved the safety of his
lamp by numerous experiments with the gas, repeated in various ways; his
earnest and impressive manner exciting in the minds of his auditors the
liveliest interest both in the inventor and his invention.
Shortly after, Sir H. Davy's model lamp was received and exhibited to the
coal-miners at Newcastle, on which occasion the observation was made by
several gentlemen, "Why, it is the same as Stephenson's!"
Notwithstanding Stephenson's claim to be regarded as the first inventor
of the Tube Safety-lamp, his merits do not seem to have been generally
recognised; and Sir Humphry Davy carried off the larger share of the
_eclat_ which attached to the discovery. What chance had the unknown
workman of Killingworth with so distinguished a competitor? The one was
as yet but a colliery engine-wright, scarce raised above the
manual-labour class, pursuing his experiments in obscurity, with a view
only to usefulness; the other was the scientific prodigy of his day, the
most brilliant of lecturers, and the most popular of philosophers.
No small indignation was expressed by the friends of Sir Humphry Davy at
Stephenson's "presumption" in laying claim to the invention of the
safety-lamp. In 1831 Dr. Paris, in his 'Life of Sir Humphry Davy,' thus
wrote:--"It will hereafter be scarcely believed that an invention so
eminently scientific, and which could never have been derived but from
the sterling treasury of science, should have been claimed on behalf of
an engine-wright of Killingworth, of the name of Stephenson--a person not
even possessing a knowledge of the elements of chemistry."
But Stephenson was far above claiming for himself any invention not his
own. He had already accomplished a far greater feat than the making of a
safety-lamp--he had constructed a successful locomotive, which was to be
seen in daily work on the Killingworth railway. By the improvements he
had made in the engine, he might almost be said to have _invented_ it;
but no one--not even the philosophers--detected the significance of that
wonderful machine. What railways were to become, rested in a great
measure with that "engine-wright of Killingworth, of the name of
Stephenson," though he was scarcely known as yet beyond the bounds of his
own district.
As to the value of the invention of the safety-lamp there could be no
doubt; and the colliery owners of Durham and Northumberland, to testify
their sense of its importance, determined to present a testimonial to its
inventor. The friends of Sir H. Davy met in August, 1816, to take steps
for raising a subscription for the purpose. The advertised object of the
meeting was to present him with a reward for "the invention of _his_
safety-lamp." To this no objection could be taken; for though the
principle on which the safety-lamps of Stephenson and Davy were
constructed was the same; and although Stephenson's lamp was,
unquestionably, the first successful lamp that had been constructed on
such principle, and proved to be efficient,--yet Sir H. Davy did invent a
safety-lamp, no doubt quite independent of all that Stephenson had done;
and having directed his careful attention to the subject, and elucidated
the true theory of explosion of carburetted hydrogen, he was entitled to
all praise and reward for his labours. But when the meeting of
coal-owners proposed to raise a subscription for the purpose of
presenting Sir H. Davy with a reward for "his invention of _the_
safety-lamp," the case was entirely altered; and Stephenson's friends
then proceeded to assert his claims to be regarded as its first inventor.
Many meetings took place on the subject, and much discussion ensued, the
result of which was that a sum of 2000 pounds was presented to Sir
Humphry Davy as "the inventor of the safety-lamp;" but, at the same time,
a purse of 100 guineas was voted to George Stephenson, in consideration
of what he had done in the same direction. This result was, however very
unsatisfactory to Stephenson, as well as to his friends, and Mr.
Brandling, of Gosforth, suggested to him that, the subject being now
fairly before the public, he should publish a statement of the facts on
which his claim was founded.
This was not at all in George's line. He had never appeared in print;
and it seemed to him a more formidable thing to write a letter for "the
papers" than to invent a safety-lamp or design a locomotive. However, he
called to his aid his son Robert, set him down before a sheet of
foolscap, and told him to "put down there just what I tell you." The
composition of this letter, as we were informed by the writer of it,
occupied more evenings than one; and when it was at length finished,
after many corrections, and fairly copied out, the father and son set
out--the latter dressed in his Sunday's round jacket--to lay the joint
production before Mr. Brandling, at Gosforth House. Glancing over the
letter, Mr. Brandling said, "George, this will never do." "It is all
true, sir," was the reply. "That may be; but it is badly written."
Robert blushed, for he thought the penmanship was called in question, and
he had written his best. Mr. Brandling, however, revised the letter,
which was shortly after published in the local journals.
Stephenson's friends, fully satisfied of his claims to priority as the
inventor of the safety-lamp used in the Killingworth and other
collieries, held a public meeting for the purpose of presenting him with
a reward "for the valuable service he had thus rendered to mankind." A
subscription was immediately commenced with this object, and a committee
was formed, consisting of the Earl of Strathmore, C. J. Brandling, and
others. The subscriptions, when collected, amounted to 1000 pounds.
Part of the money was devoted to the purchase of a silver tankard, which
was presented to the inventor, together with the balance of the
subscription, at a public dinner given in the Assembly Rooms at
Newcastle. {105} But what gave Stephenson even greater pleasure than the
silver tankard and purse of sovereigns was the gift of a silver watch,
purchased by small subscriptions amongst the colliers themselves, and
presented by them as a token of their personal esteem and regard for him,
as well as of their gratitude for the perseverance and skill with which
he had prosecuted his valuable and lifesaving invention to a successful
issue.
However great the merits of Stephenson in connexion with the invention of
the tube safety-lamp, they cannot be regarded as detracting from the
reputation of Sir Humphry Davy. His inquiries into the explosive
properties of carburetted hydrogen gas were quite original; and his
discovery of the fact that explosion will not pass through tubes of a
certain diameter was made independently of all that Stephenson had done
in verification of the same fact. It even appears that Mr. Smithson
Tennant and Dr. Wollaston had observed the same fact several years
before, though neither Stephenson nor Davy knew it while they were
prosecuting their experiments. Sir Humphry Davy's subsequent
modification of the tube-lamp, by which, while diminishing the diameter,
he in the same ratio shortened the tubes without danger, and in the form
of wire-gauze enveloped the safety-lamp by a multiplicity of tubes, was a
beautiful application of the true theory which he had formed upon the
subject.
The increased number of accidents which have occurred from explosions in
coal-mines since the general introduction of the Davy lamp, have led to
considerable doubts as to its safety, and to inquiries as to the means by
which it may be further improved; for experience has shown that, under
certain circumstances, the Davy lamp is _not_ safe. Stephenson was
himself of opinion that the modification of his own and Sir Humphry
Davy's lamp, combining the glass cylinder with the wire-gauze, was the
most secure; at the same time it must be admitted that the Davy and the
Geordy lamps alike failed to stand the severe tests to which they were
submitted by Dr. Pereira, before the Committee on Accidents in Mines.
Indeed, Dr. Pereira did not hesitate to say, that when exposed to a
current of explosive gas the Davy lamp is "decidedly unsafe," and that
the experiments by which its safety had been "demonstrated" in the
lecture-room had proved entirely "fallacious."
It is worthy of remark, that under circumstances in which the wire-gauze
of the Davy lamp becomes red-hot from the high explosiveness of the gas,
the Geordy lamp is extinguished; and we cannot but think that this fact
testifies to the decidedly superior safety of the Geordy. An accident
occurred in the Oaks colliery Pit at Barnsley, on the 20th August, 1857,
which strikingly exemplified the respective qualities of the lamps. A
sudden outburst of gas took place from the floor of the mine, along a
distance of fifty yards. Fortunately the men working in the pit at the
time were all supplied with safety-lamps--the hewers with Stephenson's,
and the hurriers with Davy's. Upon this occasion, the whole of the
Stephenson's lamps, over a space of five hundred yards, were extinguished
almost instantaneously; whereas the Davy lamps were filled with fire, and
became red-hot--so much so, that several of the men using them had their
hands burnt by the gauze. Had a strong current of air been blowing
through the gallery at the time, an explosion would most probably have
taken place--an accident which, it will be observed, could not, under
such circumstances, occur from the use of the Geordy, which is
immediately extinguished as soon as the air becomes explosive. {107}
Nicholas Wood, a good judge, has said of the two inventions, "Priority
has been claimed for each of them--I believe the inventions to be
parallel. By different roads they both arrived at the same result.
Stephenson's is the superior lamp. Davy's is safe--Stephenson's is
safer."
When the question of priority was under discussion at the studio of Mr.
Lough, the sculptor, in 1857, Sir Matthew White Ridley asked Robert
Stephenson, who was present, for his opinion on the subject. His answer
was, "I am not exactly the person to give an unbiassed opinion; but, as
you ask me frankly, I will as frankly say, that if George Stephenson had
never lived, Sir Humphry Davy could and most probably would have invented
the safety-lamp; but again, if Sir Humphry Davy had never lived, George
Stephenson certainly would have invented the safety-lamp, as I believe he
did, independent of all that Sir Humphry Davy had ever done in the
matter."
[Picture: West Moor Pit, Killingworth]