Chapter XI (3)

"Gentlemen, allow me to observe, in conclusion, that it was in pursuing those methods of analogy and experiment, by which mystery had become science, that I was fortunately led to the invention of the Safety-lamp. The whole progress of my researches has been registered in the Transactions of the Royal Society, in papers which that illustrious body has honoured by their biennial medal;[47] in which I can conscientiously assert, that I have gratefully acknowledged even the slightest hints or offers of assistance which I have received during their composition.

[47] The Rumford Medal, to be hereafter noticed.

"I state this, Gentlemen, not from vain-glory, but on account of certain calumnious insinuations which have arisen--not in the scientific world, for to that the whole progress of my researches is well known, but in a colliery. I must ever treat these insinuations with contempt; and after the honest indignation which has been expressed against them by the Coal-owners in general, I cannot feel any anxiety on the subject, nor should I have referred to it at all, did I not believe that the very persons amongst whom these insinuations originated, were extensively benefited by, and were constantly using the invention they would seek to disparage. I could never have expected that such persons would have engaged their respectable connexions in mean attempts to impeach the originality of a discovery, given to them in the most disinterested manner, and for which no return was required but an honest acknowledgment of the benefit, founded upon truth and justice.

"I do not envy them their feelings, particularly at the present moment: I do not wish to enquire into their motives: I do hope, however, that their conduct has been prompted by ignorance rather than by malevolence, by misapprehension rather than by ingratitude.

"It was a new circumstance to me, that attempts to preserve human life, and to prevent human misery, should create hostile feelings in persons who professed to have similar objects in view.

"Gentlemen, I have had some opposition, much labour, and more anxiety, during the course of these researches; but had the opposition, the labour, and the anxiety been a thousand times as great, the events of this day would have been more than a compensation."

Sir Humphry, after drinking the health and happiness of the company, proposed as a sentiment--"Prosperity to the Coal-trade."

The healths of the Duke of Northumberland, the Bishop of Durham, and the Reverend Dr. Gray, were drunk in succession.

At ten o'clock, Sir Humphry, accompanied by the chairman, retired amidst the enthusiastic plaudits of a meeting, the object of which being one of convivial benevolence, the effect was that of unclouded hilarity.

The party which had supported the claims of Mr. Stephenson had also their meeting; and it was held on the 1st of November. At this meeting it was resolved, "That it was the opinion of the persons present, that Mr. G. Stephenson having discovered the fact, that explosions of hydrogen gas will not pass through tubes and apertures of small dimensions, and having been the first to apply the principle to the construction of a Safety-lamp, is entitled to some reward."

A committee was accordingly formed to carry this resolution into effect, at the head of which was placed the name of the Earl of Strathmore.

The respectable body of Coal-owners, under whose auspices the invention of Sir Humphry Davy had been introduced and rewarded, felt that they owed it to their own characters to repel assertions which amounted to a charge against themselves of ingratitude and injustice: a general meeting was accordingly summoned, at the Assembly-rooms in Newcastle, on the 26th of November 1817, J. G. Lambton, Esq. M.P. in the chair--when it was resolved,

"That the Resolutions passed at the Meeting of the friends of Mr. G. Stephenson on the 5th instant, impugn the justice and propriety of the proceedings of a meeting of the Coal-trade on the 31st of August 1816:

"That the present meeting, therefore, feel themselves called upon, as an act of justice to the character of their great and disinterested benefactor, Sir Humphry Davy, and as a proof that the Coal-trade of the North in no way sanctions the resolutions of Mr. Stephenson's friends, to state their decided conviction, that the merit of having discovered the fact, that explosions of fire-damp will not pass through tubes and apertures of small dimensions, and of having applied that principle to the construction of a Safety-lamp, _belongs to Sir Humphry Davy alone_.

"That this meeting is also decidedly of opinion, from the evidence produced in various publications by Mr. George Stephenson and his friends, subsequently to the meeting of the Coal-trade which was held on the 18th of March 1816, as well as from the documents which have been read at this meeting, that Mr. Stephenson _did not_ discover the fact, that explosions of fire-damp will not pass through tubes and apertures of small dimensions; and that he _did not_ apply that principle to the construction of a Safety-lamp; and that the latest lamps made by Mr. Stephenson are evident imitations of those of Sir Humphry Davy, and that, even with that advantage, they are so imperfectly constructed as to be actually unsafe.

"That the above resolutions be published thrice in the Newcastle papers, and in the Courier, Morning Chronicle, and Edinburgh Courant; and that printed copies thereof be sent to the Lords Lieutenants of the two counties, to the Lord Bishop of Durham, and to the principal owners and lessors of collieries upon the Tyne and Wear."

The following letter from Sir Humphry Davy announces the farther measures which he also had thought proper to pursue, in order to counteract the impression which the meeting of Mr. Stephenson's friends might have produced on the less informed part of the public.

TO J. G. LAMBTON, ESQ. M.P.

November 21, 1817.

MY DEAR SIR,

I shall send off by this post a copy of the resolutions, which
will appear to-morrow in the Chronicle and Courier.

The men of science who have signed these resolutions are the
first chemists and natural philosophers of the country, with
the President of the Royal Society, the most illustrious body
in Europe, at their head.

It is disagreeable to be thus obliged to use artillery for
the destruction of bats and owls; but it was necessary that
something should be done.

The Messrs. ---- have for a long time been endeavouring to
destroy my peace of mind; my offence being that of conferring a
benefit.

The only persons I knew in Newcastle, before I gave the
Safety-lamp to the Coal-owners, were Dr. Headlam and Mr. Bigge,
so that friends I had none; and the few persons with whom I
had a slight acquaintance, and who were civil to me before I
discovered the Safety-lamp, became my enemies. It requires a
deep metaphysician to explain this--Can it be that I did not
make them the medium of communication to the colliers?--But I
quit a subject to which I have no desire to return, and shall
only recollect that day when your eloquence touched my feelings
more than it flattered my self-love.

Believe me, &c. &c.

H. Davy.

The following are the Resolutions of a Meeting adverted to in the preceding letter, and which was held "for considering the Facts relating to the Discovery of the Lamp of Safety."

Soho Square, Nov. 20, 1817.

"An advertisement having been inserted in the Newcastle
Courant, of Saturday, November 7, 1817, purporting to contain
the Resolutions of 'A Meeting held for the purpose of
remunerating Mr. George Stephenson, for the valuable service he
has rendered mankind by the invention of his Safety-lamp, which
is calculated for the preservation of human life in situations
of the greatest danger,'

"We have considered the evidence produced in various
publications by Mr. Stephenson and his friends, in support of
his claims; and having examined his lamps, and enquired into
their effects in explosive mixtures, are clearly of opinion--

"First,--That Mr. George Stephenson _is not_ the author of the
discovery of the fact, that an explosion of inflammable gas
will not pass through tubes and apertures of small dimensions.

"Secondly,--That Mr. George Stephenson _was not_ the first to
apply that principle to the construction of a Safety-lamp,
none of the lamps which he made in the year 1815 having been
safe, and there being no evidence even of their having been
made upon that principle.

"Thirdly,--That Sir Humphry Davy not only discovered,
independently of all others, and without any knowledge of the
unpublished experiments of the late Mr. Tennant on Flame, the
principle of the non-communication of explosions through small
apertures, but that he has also the sole merit of having first
applied it to the very important purpose of a Safety-lamp,
which has evidently been imitated in the latest lamps of Mr.
George Stephenson.

(Signed) "JOSEPH BANKS, P.R.S.
"WILLIAM THOMAS BRANDE,
"CHARLES HATCHETT,
"WILLIAM HYDE WOLLASTON."

Thus terminated a controversy, the discussion of which, I am well aware, many of my readers will consider as having been protracted to a tedious, and perhaps to an unnecessary extent; but the biographer had no alternative. In passing it by without a notice, he would have violated his faith to the public, have given a tacit acknowledgment of the claims of Stephenson, and, in his judgment, have committed an act of gross injustice to the illustrious subject of his history; while by giving only an abridged statement, he would have furnished a pretext for doubt, and an opportunity for malevolence.

It is due also to Sir Humphry Davy to observe, that had he practised more reserve in the communication of his results, the spirit of rivalry would have expired without a struggle,--for it derived its only support and power from the generosity of its victim. Had he secured for himself the advantages of his invention by patent, he might have realized wealth to almost any extent; but to barter the products of his intellectual exertions for pecuniary profit, was a course wholly at variance with every feeling of Davy's mind; and we therefore find him, in the advancement, as at the commencement of his fleeting career, spurning the golden apples from his feet, and hastening to the goal for that prize which could alone reward all his labours--the meed of immortal fame.

From a letter dated Newcastle, August 1830, which I had the pleasure to receive from Mr. Buddle, I extract the following interesting passage:--

"In the autumn of 1815, Sir Humphry Davy accompanied me into some of our fiery mines, to _prove_ the efficacy of his lamp. Nothing could be more gratifying than the result of those experiments, as they inspired every body with perfect confidence in the security which his invention had afforded.

"Sir Humphry was delighted, and I was overpowered with feelings of gratitude to that great genius which had produced it.

"I felt, however, that he did not contemplate any pecuniary reward; and, in a private conversation, I remonstrated with him on the subject. I said, 'You might as well have secured this invention by a patent, and received your five or ten thousand a-year from it.' The reply of this great and noble-minded man was,--'No, my good friend, I never thought of such a thing; my sole object was to serve the cause of humanity; and, if I have succeeded, I am amply rewarded in the gratifying reflection of having done so.' I expostulated, saying, that his ideas were much too philosophic and refined for the occasion. He replied, 'I have enough for all my views and purposes; more wealth might be troublesome, and distract my attention from those pursuits in which I delight;--more wealth,' he added, 'could not increase either my fame or my happiness. It might, undoubtedly, enable me to put four horses to my carriage; but what would it avail me to have it said that Sir Humphry drives his carriage-and-four?'"

The present Bishop of Bristol, to whom the world is so greatly indebted for having first called the attention of Sir Humphry Davy to the subject of explosions from fire-damp, and who has kindly interested himself in my arduous and anxious undertaking, was desirous to obtain for me the latest accounts with respect to the Safety-lamp, as to the constancy of its use, and the extent of its security; and his Lordship informs me, that having applied to Mr. Buddle and Mr. Fenwick for information upon these points, their answers have been most satisfactory; at the same time, his Lordship transmitted me much valuable information, which was accompanied by the following letter from Mr. Buddle.

TO THE RIGHT REVEREND THE LORD BISHOP OF BRISTOL.

Wall's-End, August 11, 1830.

MY LORD,

I have the honour to acknowledge the receipt of your Lordship's
letter of yesterday's date. I am glad your Lordship has
interested yourself in Doctor Paris's work, and I hope that
he will be enabled, through the assistance of Sir Humphry's
friends, to do ample justice to the genius and worth of that
excellent man.

I should be very happy if any letters of mine could assist
Dr. Paris in doing justice to his merits in the invention of
the Safety-lamp; and I shall with pleasure submit to your
Lordship's better judgment and discretion the selection of such
of them as may seem to be conducive to that object.

I do not find that any improvement whatever has been made,
either in the principle or construction of the _original lamp_,
as presented to us by Sir Humphry. His transcendent genius
seems to have anticipated every thing belonging to the subject,
and has left nothing more to be done.

I have the honour to be,
My Lord, with great respect,
Your Lordship's most obedient, humble servant,
JOHN BUDDLE.

In consequence of some late reports of accidents in the mines, I requested my friend Sir Cuthbert Sharp to make certain enquiries in the mining districts; and for this purpose, I sent him a string of queries, to which I begged him to obtain answers. These questions were submitted to Mr. Buddle, and they produced the following letter.

TO SIR CUTHBERT SHARP.

Newcastle, August 28, 1830.

MY DEAR SIR CUTHBERT,

I return Dr. Paris's letter, and shall briefly answer his
enquiries.

If the Davy lamp was exclusively used, and due care taken in
its management, it is certain that few accidents would occur
in our coal mines; but the exclusive use of the "_Davy_" is
not compatible with the working of many of our mines, in
consequence of their not being workable without the aid of
gunpowder.

In such mines, where every collier must necessarily fire, on
the average, two _shots_ a-day, we are exposed to the risk of
explosion from the ignition of the gunpowder, even if no naked
lights were used in carrying on the ordinary operations of the
mine.

This was the case in Jarrow Colliery, at the time the late
accident happened. As the use of gunpowder was indispensable,
naked lights were generally used, and the accident was
occasioned by a '_bag_' of inflammable air forcing out a large
block of coal, in the face of a drift, from a fissure in which
it had been pent up, perhaps from the Creation, and firing at
the first naked light with which it came in contact, after
having been diluted down to the combustible point by a due
admixture of atmospheric air.

As to the number of old collieries and old workings which
have been renovated, and as to the quantity of coal which has
been, and will be saved to the public by the invention of the
"_Davy_," it is scarcely possible to give an account, or to
form an estimate.

In this part of the country, 'Walker's Colliery,' after having
been completely worked out, according to the former system,
with candles and steel-mills, and after having been abandoned
in 1811, was reopened in 1818 by the aid of the "_Davy_" and
has been worked on an extensive scale ever since, and may
continue to be worked for an almost indefinite period.

Great part of the formerly relinquished workings of Wall's-end,
Willington, Percy-main, Hebburn, Jarrow, Elswick, Benwell,
&c. &c., as well as several collieries on the Wear, have been
recovered, and are continued in work by the invention of the
"_Davy_."

If I had only what you know perfectly well I have not--TIME, I
could write a volume on this subject.

I shall shortly, through the medium of a friend, get an
important paper on the subject of the "_Davy_," put into Dr.
Paris's hands.

Believe me, my dear Sir Cuthbert,
To remain yours very faithfully,
JOHN BUDDLE.

The Bishop of Bristol has placed at my disposal a communication from Mr. Fenwick, a gentleman of much practical ability, which affords additional evidence of the utility of the lamp; from which the following is an extract.

"Sir H. Davy's safety-lamp has afforded much security in the general working of mines, particularly by enabling the coal-owner to work, in several situations, the pillars of coal formerly left therein, which, under the system of working by candles, or open flame, was deemed hazardous and impracticable; and, in consequence, one-sixth part more of coal may be estimated as obtainable from those mines which are subject to hydrogen gas. Also in the working of the pillars of coal, (commonly called the second working,) great advantages and securities, as well as saving of expenses, have resulted from the use of this lamp, not only to the lessees of collieries, inasmuch as more coal is obtained from a given space than before, (particularly in collieries subject to fire-damp,) but also to the lessor of such mines, by their being more productive, and of course more durable than heretofore.

"Another advantage results from the use of this Safety-lamp, and in the working of the pillars in particular. It is found now, through experience, that the changeable state of the atmosphere, which our barometers daily indicate, has a most powerful effect on the noxious air in mines; as, from a sudden change in the atmosphere, indicated by the rapid fall of the mercury in the barometrical tube, a rapid discharge of noxious gas into the workings and excavations of the mine is the consequence, caused by the want of the atmospheric equilibrium:[48] in which case the mine becomes suddenly surcharged with hydrogen, and if worked by the light of _open flame_, an explosion may take place before the possibility of such a circumstance can even be suspected; but if worked by the Safety-lamp, it is only shown by the gas in the lamp becoming a pillar of harmless flame. This circumstance frequently takes place when any atmospheric change causes the mercury in the barometer to sink to twenty-eight inches and a half or thereabouts."

[48] This is a very interesting fact, and gives much support to
the theory advanced at page 62 of this volume.

In the year 1825, Sir Humphry Davy had the honour to receive from the Emperor Alexander of Russia, a superb silver gilt vase, standing in a circular tray enriched with medallions. On the cover was a figure, of about sixteen or eighteen inches in height, representing the God of Fire, weeping over his extinguished torch.

The circumstances under which this vase was presented have been communicated to me by Mr. Smirnove, Secretary to the Embassy.

TO J. A. PARIS, M.D.

Wigmore Street, May 29, 1830.

DEAR SIR,

It was in the month of April, or May, 1815, that the late Sir
Humphry Davy expressed to Prince, then Count, Lieven, his wish
to offer to the Emperor of Russia a model of his Safety-lamp,
which he had recently improved, accompanied by an explanatory
pamphlet on the subject.

Prince Lieven of course complied with this request; and
the Emperor having been pleased to accept it, ordered the
Ambassador, in November of the same year, to thank Sir Humphry
for it in his Majesty's name, and to assure him how much his
Majesty appreciated the merit of an invention, the double
effect of which was to favour the progress of more than one
branch of industry, and to ensure the safety of persons
employed in the coal-mines, against those fatal accidents
which had hitherto so frequently occurred. The Ambassador,
at the same time, delivered to Sir Humphry a silver-gilt
Vase,[49] in the name of the Emperor, in testimony of the high
satisfaction with which that sovereign had been pleased to
accept the object in question. I beg you to believe me, with
regard and esteem,

Your faithful servant,
JOHN SMIRNOVE.

[49] Of the value of about one hundred and eighty guineas.

It is well known to the friends of Davy, that in his conversation as well as in his correspondence, he always dwelt with peculiar satisfaction and delight upon the invention of his Safety-lamp.

Mr. Poole, in a letter lately addressed to me, observes--"How often have I heard him express the satisfaction which this discovery had given him. 'I value it,' said he, 'more than any thing I ever did. It was the result of a great deal of investigation and labour; but, if my directions be only attended to, it will save the lives of thousands of poor labourers. I was never more affected,' he added, 'than by a written address which I received from the working colliers, when I was in the North, thanking me, in behalf of themselves and their families, for the preservation of their lives.' I remember how delighted he was when he showed me the service of plate presented to him by those very men and their employers, as a testimony of their gratitude."

The following letter evinces a similar feeling.

TO THOMAS POOLE, ESQ.

Queen's Square, Bath, Oct. 29, 1816.

MY DEAR POOLE,

It is very long since any letters have passed between us. The
affections and recollections of friendly intercourse are of a
very adhesive nature; and I think you will not be displeased at
being put in mind that there is an old friend not very far from
you, who will be very glad to see you.

Bath does not suit me much, nor should I remain here, but
my wife has been indisposed, and the waters seem to benefit
her, and promise to render her permanent service, and if that
happens, I shall be pleased even with this uninteresting city.

I have seen many countries and nations since we met.

* * * * *

I have just come from the North of England, where it has
pleased Providence to make me an instrument for preserving the
lives of some of my fellow-creatures. You, I know, are of that
complexion of mind that the civic crown will please you more
than even the victor's laurel wreath.

I have a bed, though a small one, at your service; if you can
come here for two or three days, I assure you we shall be most
happy to see you. We shall remain in Bath about three weeks.
I shall be absent for a few days in the beginning of next
week, and after that I shall be stationary till the middle of
November. Give me a few lines, and say when we may expect you.

I am, my dear Poole, very sincerely yours,
H. DAVY.

TO THE SAME.

Grosvenor Street, Dec. 3, 1817.

MY DEAR POOLE,

The late melancholy event[50] has thrown a gloom over London,
and indeed over England. The public feeling is highly
creditable to the moral tone of the people.

The loss of a Princess, known only by good qualities, living
in a pure and happy state of domestic peace, is in itself
affecting; but when it is recollected that two generations of
sovereigns of the first people in the world have been lost at
the same moment, the event becomes almost an awful one.

I go on always labouring in my vocation. I am now at work on a
subject almost as interesting as the last which I undertook.
It is too much to hope for the same success; at least I will
deserve it.

When you come to town in the spring, which I trust you will do,
I shall show you my service of plate. I do not think you will
like it the less for the cause of the gift.

I am not sure whether I shall not take a run down to Nether
Stowey and the west for a few days, if you encourage me with
any hopes of the estate[51] and of woodcocks. You will fix my
plans.

I shall be disengaged between the 15th and Christmas, and shall
like to revisit Lymouth, and above all to shake you by the
hand.

Lady D. is in better health than I have ever known her to
possess. She begs her kind remembrances.

I am, my dear Poole, most affectionately yours,
H. DAVY.

[50] The death of the Princess Charlotte.

[51] He here alludes to an estate in the neighbourhood of Nether
Stowey, which he wished to purchase, and about which he had
requested Mr. Poole to make enquiries.

In a strictly scientific point of view, the most interesting results which have arisen out of the investigation for constructing a Safety-lamp, are perhaps those which have made us better acquainted with the true nature of flame, and the circumstances by which it is modified; and which have led to some practical views connected with the useful arts.

It is, I think, impossible to enter into the details of those curious investigations[52] which, under the title of "Some Researches on Flame," were communicated to the Royal Society, and read before that body on the 16th of January 1817, without being forcibly struck with the address by which Davy, in the first instance, brought abstract science to promote and extend practical knowledge; and then, as it were by a species of multiplied reflection, applied the new facts thus elicited for the farther extension of speculative truth; which in its wider range became again instrumental in disclosing a fresh store of useful facts. It may be said to have been the power of dexterously combining such methods which constituted the felicity of his genius; for, in general, each of them requires for its successful application a mind of quite a distinct order and construction. Mr. Babbage has very justly observed, that those intellectual qualifications which give birth to new principles or to new methods, are of quite a different order from those which are necessary for their practical application. Davy furnished the exception that was necessary to make good the rule.

[52] A short notice of them first appeared in the third number
of the "Journal of Science and the Arts," edited at the Royal
Institution.

He detects, in the first instance, the general principle of inflammable gas, in a state of combustion, being arrested in its progress by capillary tubes; he next applies it to the construction of a Safety-lamp, and then, by observing the phenomena which this lamp exhibits, is led to novel views respecting the nature and properties of flame.--I shall endeavour to offer a popular view of the curious and interesting truths disclosed by this latter research.

He had observed that, when the coal gas burnt in the iron cage, its colour was pale, and its light feeble; whereas the fact is rendered familiar to us all by the flame of the gas lights, that in the open air carburetted hydrogen burns with great brilliancy. Upon reflecting on the circumstances of the two species of combustion, he was led to believe that the cause of the superiority of the light in the latter case might be owing to a _decomposition_ of a part of the gas towards the interior of the flame, where the air was in the smallest quantity; and that the consequent deposition of charcoal might first by its _ignition_, and afterwards by its _combustion_, contribute to this increase of light. A conjecture which he immediately verified by experiment.[53]

[53] This theory of Davy is well illustrated by the change
produced in the flame of gas-light, when acted upon by the
wind, as may be seen during an illumination. The loss of light
under these circumstances evidently arises from the more rapid
combustion of the gas, by its more complete admixture with air;
in consequence of which the decomposition above described does
not take place.

The intensity therefore of the light of flames depends principally upon the production and ignition of _solid_ matter in combustion, so that heat and light are in this process independent phenomena.

These facts, Davy observes, appear to admit of many applications; in explaining, for instance, the appearance of different flames--in suggesting the means of increasing or diminishing their light, and in deducing from their characters a knowledge of the composition of their constituent parts.

The point of the inner blue flame of a candle or lamp urged by the blow-pipe, where the heat is the greatest and the light the least, is the point where the whole of the charcoal is burnt in its gaseous combinations, without previous ignition. The flames of phosphorus and of zinc in oxygen, and that of potassium in chlorine, afford examples of intensity of light depending upon the production of _fixed_ solid matter in combustion; while on the contrary, the feebleness of the light of those flames, in which gaseous and volatile matter is alone produced, is well illustrated by those of hydrogen and sulphur in oxygen, or by that of phosphorus in chlorine.

From such facts, he is inclined to think that the luminous appearance of shooting stars and meteors cannot be owing to any inflammation of gas, but must depend upon the ignition of solid matter. Dr. Halley calculated the height of a meteor at ninety miles, and the great American meteor, which threw down showers of stones, was estimated at only seventeen miles high. The velocity of the motion of such bodies must in all cases be immensely great, and the heat thus produced by the compression of the most rarefied air, Davy thinks, must be sufficient to ignite the mass; and that all the phenomena may be explained by assuming that _falling stars_ are small solid bodies moving round the earth in very eccentric orbits, which become ignited only when they pass with immense velocity through the upper regions of the atmosphere, and which, when they contain either combustible or elastic matter, throw out stones with explosion.

By the application of such a principle did he also infer the composition of a body from the character of its flame: thus, says he, Ether, during its combustion, would appear to indicate the presence of _olefiant gas_. Alcohol burns with a flame similar to that of a mixture of carbonic oxide and hydrogen; so that the first is probably a binary compound of olefiant gas and water, and the second of carbonic oxide and hydrogen.

When the proto-chloride of copper is introduced into the flame of a candle or lamp, it affords a peculiar dense and brilliant red light, tinged with green and blue towards the edges, which seems to depend upon the separation of the chlorine from the copper by the hydrogen, and the ignition and combustion of the solid copper and charcoal.

The acknowledged fact of the brightest flames yielding the least heat is easily reconciled, when we learn that the light depends upon fixed matter which carries off the heat. It is equally obvious, that by art we may, for practical purposes, easily modify these phenomena.

In the next place, having observed that wire-gauze cooled down flame beyond its combustible point, he was led to enquire into the nature of pure flame; and he readily demonstrated it to be _gaseous matter heated so highly as to be luminous_; and that the temperature necessary for such an effect was much greater than had been imagined, varying, however, in different cases. The flame of a common lamp he proved, by a very simple experiment, to exceed even the white heat of solid bodies, and which is easily shown by the simple fact of heating a piece of platinum wire over the chimney of an Argand lamp fed with spirit of wine; when it will be seen that air, which is not of sufficient temperature to appear luminous, is still sufficiently hot to impart a white heat to a solid body immersed in it.

The fact of different gaseous bodies requiring different degrees of heat to raise them into flame, was an inference immediately deducible from the phenomena of his _safety gauze_. A tissue of one hundred apertures to the square inch, made of wire of one-sixtieth, will, at common temperatures, intercept the flame of a spirit-lamp, but not that of hydrogen; and, when strongly heated, it will no longer arrest the flame of the spirit-lamp. A tissue which, when red-hot, will not interrupt the flame of hydrogen, will still intercept that of olefiant gas; and a heated tissue, which would communicate explosion from a mixture of olefiant gas and air, will stop an explosion of fire-damp. Fortunately for the success of the Safety-lamp, carburetted hydrogen requires so high a temperature to carry on its combustion, that even metal, when white-hot, is far below it; and hence red-hot gauze, in sufficient quantity, and of the proper degree of fineness, will abstract heat enough from the flame to extinguish it.

The discovery of the high temperature which is necessary for the maintenance of flame, suggested to the philosopher the reason of its extinction under various circumstances. He considers, that the common operation of blowing out a candle principally depends upon the cooling power of the current of air projected into the flame;[54] and he observes, that the hottest flames are those which are least easily blown out. He farther illustrated this subject by surrounding a very small flame with a ring of _metal_, which had the effect of cooling it so far as to extinguish it; but a ring of _glass_, of similar dimensions and diameter, being a less perfect conductor of heat, produced no such effect.

[54] _Quere._ Is this theory correct? May not the effect be
mechanical, the appulse of the air separating the flame from
the wick.--Upon the principle suggested by Davy, how are we to
explain the fact of rekindling the flame by a blast?

It had been long known that flame ceased to burn in highly rarefied air; but the degree of rarefaction necessary for this effect had been very differently stated. The cause of the phenomenon was generally supposed to depend upon a deficiency of oxygen.

In the commencement of his enquiry into this subject, Davy observed that the flame of hydrogen gas, the degree of rarefaction and the quantity of air being the same, burnt longer when it issued from a larger than a smaller jet,--a fact the very reverse of that which must have happened had the flame expired for want of oxygen; he moreover observed, that when the larger jet was used, the point of the glass tube became white-hot, and continued red-hot till the flame was extinguished: he therefore concluded, that the heat communicated to the gas by this tube was the cause of its protracted combustion, and that _flame expired in rarefied air, not for want of nourishment from oxygen, but for want of heat, and that if its temperature could be preserved by some supplementary aid, the flame might be kept burning_. The experiment by which he confirmed this theory was as beautiful as it was satisfactory.

He burnt a piece of camphor in a _glass_ tube, under the receiver of an air-pump, so as to make the upper part of the tube red-hot; its inflammation was found to continue when the rarefaction was nine times; but by repeating the experiment in a _metallic_ tube, which could not be so considerably heated by it, it ceased after the rarefaction exceeded six times.

It follows then that by artificially imparting heat,[55] bodies may be made to burn in a rarefied air, when under other circumstances they would be extinguished.

[55] "It is upon this principle that, in the Argand lamp, the
Liverpool lamp, and in the best fire-places, the increase of
effect does not merely depend upon the rapid current of air,
but likewise upon the heat preserved by the arrangement of
the materials of the chimney, and communicated to the matters
entering into inflammation." The art of making a good fire
depends also upon the same principle of economising the heat.

The following may be considered as an _experimentum crucis_, in proof of the fact that combustibility is neither increased nor diminished by rarefaction.

He introduced the flame of hydrogen, in which was inserted a platinum wire, into a receiver of rarefied air, and he found that, as long as the metal remained at a dull red-heat, the flame continued to burn: now it so happens that the temperature, at which platinum approaches a red-heat, is precisely that at which hydrogen inflames under the ordinary pressure of the atmosphere; whence it follows, that its combustibility is not altered by rarefaction.

The same law was found to apply to the flames of other bodies; those requiring the least heat for their combustion always sustaining the greater rarefaction without being extinguished.[56]

[56] From a calculation of the ratio in which the density of the
atmosphere decreases with its altitude, and from that of the
relative combustibility of different bodies, it follows that
the taper would be extinguished at a height of between nine and
ten miles--hydrogen, between twelve and thirteen--and sulphur,
between fifteen and sixteen.

Hitherto he had only considered the effects of rarefaction, when produced by the diminution of pressure; he had next to investigate the phenomena of rarefaction when occasioned by expansion from heat.

The experiments of M. de Grotthus had apparently shown that rarefaction by heat destroys the combustibility of gaseous mixtures; those of Davy, however, proved that it enables them to explode at a lower temperature.

In the progress of this research, while passing mixtures of hydrogen and oxygen through heated tubes, the heat being still below redness, he observed that steam was formed without any combustion.

Here was a slow combination without combustion, as long since observed with respect to hydrogen and chlorine, and oxygen and metals; and he believes that such a phenomenon will happen at certain temperatures with most substances that unite by heat. On trying charcoal, he found that at a temperature which appeared to be a little above the boiling point of quicksilver, it converted oxygen pretty rapidly into carbonic acid, without any luminous appearance, and that, at a dull red-heat, the elements of olefiant gas combined in a similar manner with oxygen, slowly and without explosion.

It occurred to Davy, in the progress of these experiments, that, during this species of slow combination, although the increase of temperature might not be sufficient to render the gaseous matters luminous, or to produce flame, it might still be adequate to ignite solid matters exposed to them. It was while engaged in devising experiments to ascertain this fact, that he was accidentally led to the discovery of the continued ignition of platinum wire, during the slow combination of coal gas with atmospheric air; the circumstances of which have been already related, as well as the curious invention to which the application of the fact gave origin.[57]

[57] See page 100 of this volume.

For this and his preceding papers on the subjects of flame and combustion, the President and Council of the Royal Society adjudged to Sir Humphry Davy the gold and silver medals, on the donation of Count Rumford;[58] and never, I will venture say, did a society in awarding a prize more faithfully comply with the intentions of its founder.

[58] At the Anniversary of the Royal Society, November 1796,
Count Rumford transferred one thousand pounds, Three per Cent.
Consols, to the use of the Society, on condition that a premium
should be biennially awarded to the author of the most important
discovery, or useful invention, made known in any part of Europe
during the preceding two years, on the subject of HEAT AND LIGHT.
In regard to the form in which this premium was to be conferred,
he requested that it might always be given in two medals, struck
in the same die, the one of gold, and the other of silver.

Should not any discovery or improvement be made during any terms
of years, he directed that the value of the medals should be
reserved, and being laid out in the purchase of additional stock,
go in augmentation of the capital of this premium.

Medals upon this foundation have been successively voted to
Professor Leslie, for his Experiments on Heat, published in
his work entitled "An Experimental Enquiry into the Nature
and Properties of Heat;"--To Mr. William Murdoch, for his
publication "On the Employment of Gas and Coal for the purpose of
Illumination;"--to M. Malus, for his discoveries of certain new
properties of reflected light;--to Dr. Wells, for his Essay on
Dew;--to Sir Humphry Davy, as above stated;--to Dr. Brewster, for
his Optical Investigations;--and, lastly, to Mr. Fresnel, for his
optical researches.

On the completion of these laborious enquiries, it was thought expedient to give a wider circulation to their results than the publication of them in the Philosophical Transactions was calculated to afford; and Sir Humphry Davy was therefore induced to reprint his principal memoirs, so as to form an octavo volume,[59] which might be accessible to the practical parts of the community.

[59] "On the Safety-lamp for Coal Mines, with some Researches on
Flame.--London, 1818."

The enlightened friends of science very reasonably expected that a service of such importance to society as the invention of the Safety-lamp, would have commanded the gratitude of the State, and obtained for its author a high parliamentary reward; nor were there wanting zealous and disinterested persons to urge the claims of the Philosopher: but a Government which had bestowed a splendid pension upon the contriver of an engine[60] for the destruction of human life, refused to listen to any proposition for the reward of one who had invented a machine for its preservation. It is true that, in consideration of various scientific services, they tardily and inadequately acknowledged the claims of Davy, by bestowing upon him the dignity of Baronetcy[61]--a reward, it must be confessed, that neither displayed any regard to his condition, nor implied the just estimate of his merits. The measure of value, however, enables us to judge of the standard by which the State rates the various services to society; and deeply is it to be lamented that the disproportioned exaltation of military achievement, crowned with the highest honours, depresses respect for science, and raises a false and fruitless object of ambition.

[60] Sir William Congreve, in addition to other marks of favour,
received a pension of twelve hundred a-year, for the invention of
his Rocket; or, in the exact terms of the grant, "for inventions
calculated to destroy or annoy the enemy."

[61] He was created a Baronet on the 20th of October, 1818.

The passion for arms is a relict of barbarity derived from the feudal ages; the progress of civilization, and the cultivation of the mind, should have led us to prefer intellectual to physical superiority, and to recognise in the successes of science the chief titles to honour. This reversal of the objects of importance can never be redressed until the aristocracy shall be possessed of a competent share of scientific knowledge, and instructed to appreciate its value. To effect such a change, the system of education so blindly and obstinately continued in our great public schools, must be altered; for minds exclusively applied to classical pursuits, and trained to recognise no other objects of liberal study, are indisposed and indeed disqualified for enquiries ministering to the arts of life, and arrogantly despised for their very connexion with utility. It is in the early ignorance of the rudiments of science that the after negligence of science has its source.

The instances in proof of the extent of the ignorance and indifference I have noted, and of their pernicious effects upon the most important interests of society, especially legislation, and the administration of justice, are abundant. In Parliament, how is a question of science treated? In our courts of law, and criminal investigation, it is lamentable to observe the frequent defeat of justice, arising from erroneous conception, or from the utter absence of the requisite knowledge. In the ordinary affairs of life, we see conspicuous, amongst the dupes of quackery and imposture, those whose stations should imply the best instruction, and whose conduct, unfortunately, has the effect of example.

A contempt far-spreading, and proceeding from the well-springs of truth, is rapidly rising against this exalted ignorance; the industrious classes of society are daily becoming more imbued with knowledge upon scientific subjects, and the nobility, if they would preserve their superiority in social consideration, must descend to the popular improvement.

* * * * *

Before concluding the present chapter, I must carry back my history to the year 1815, for the purpose of recording a circumstance in the life of Davy, which, while it exemplifies his general love of science, evinces the local attachment he retained for the town of his birth.

In the year 1813, the Geological Society of Cornwall was established at Penzance. Its objects are to cultivate the sciences of Mineralogy and Geology, in a district better calculated perhaps for such pursuits than any other spot in Europe,--to register the new facts which are continually presenting themselves in the mines, and to place upon permanent record, the history of phenomena which had hitherto been entrusted to oral tradition; but, above all, its object was to bring science in alliance with art; to prevent the accidents which had so frequently occurred from explosion in the operation of blasting rocks; and, in short, to render all the resources of speculative truth subservient to the ends of practical improvement.

No sooner had the establishment of so useful an institution been communicated to Davy, than he testified his zeal for its welfare by a handsome donation to its funds; which was followed by a present of a very extensive suite of specimens, illustrative of the volcanic district of Naples, and which had been collected by himself. He also afterwards communicated to the Society a memoir on the Geology of Cornwall, which has been published in the first volume of its Transactions.

In this paper, he discusses several of the more difficult questions connected with the origin of veins.

He first observed the granitic veins, which have called forth so much attention from geologists, about the year 1797; probably before they had excited much scientific notice: he is disposed to regard them as peculiar to the low metalliferous granite and mica formations; he had seen several cases of granite veins near Dublin, in the Isle of Arran, and in other parts of Scotland; he had also observed several instances near Morlaix in Brittany, but he had in vain searched for them in the points of junction of the schist and granite, both in the Maritime, Savoy, Swiss, and Tyrolese Alps, and likewise in the Oriental Pyrenees.

The _serpentine_ district of Cornwall, he thinks, has not yet met with the attention it deserves. "I have seen no formation," says he, "in which the nature of serpentine is so distinctly displayed. The true constituent parts of this rock appear to be _resplendent hornblende_ and _felspar_; it appears to differ from _sienite_ only in the nature of the _hornblende_, and in the chemical composition of its parts, and in being intersected by numerous veins of _steatite_ and _calcareous spar_."

The nature and origin of the veins of _steatite_ in serpentine, he considers as offering a very curious subject for enquiry. "Were they originally crystallized," he asks, "and the result of chemical deposition? or have they been, as for the most part they are now found, mere mechanical deposits?" He is inclined to the latter opinion. The felspar in serpentine, he observes, is very liable to decomposition, probably from the action of carbonic acid and water on its alkaline, calcareous, and magnesian elements; and its parts washed down by water and deposited in the chasms of the rocks, he thinks would necessarily gain that kind of loose aggregation belonging to steatite.

He had some years before made a rude, comparative analysis of the felspar in serpentine, and of the soap-rock, when he found the same constituents in both of them, except that there was not any alkali or calcareous earth in the latter substance. It is very difficult to conceive, he says, that steatite was originally a crystallized substance which has been since decomposed; for, in that case, it ought to be found in its primitive state in veins which are excluded from the action of air and water; whereas it is easy to account for the hardness of some species of steatite on the former hypothesis; for mere mechanical deposits, when very finely divided, and very slowly made, adhere with a very considerable degree of force. A remarkable instance of this kind occurred to him amongst the chemical preparations of the late Mr. Cavendish, which, on the decease of that illustrious philosopher, had been presented to him by Lord George Cavendish: there was a bottle which had originally contained a solution of silica by potash; the cork, during the lapse of years, had become decayed, and the carbonic acid of the atmosphere had gradually precipitated the earth, so that it was found in a state of solid cohesion; the upper part was as soft as the steatite, but the lower portion was extremely hard, was broken with some difficulty, and presented an appearance similar to that of chalcedony.

In speaking generally of the mineralogical interest of Cornwall, he observes, that "it may be regarded, [Greek: kat' exochên], as the country of veins; and that it is in veins that the most useful as well as the most valuable minerals generally exist, that the pure specimens are found which serve to determine the mineralogical species, and that the appearances seem most interesting in their connexion with geological theory. Thus veins, which now may be considered in the light of the most valuable cabinets of nature, were once her most active laboratories; and they are equally important to the practical miner, and to the mineralogical philosopher."

With regard to the general conformation of Cornwall, he states it to be in the highest degree curious, and he considers that the facts which it offers are illustrative of many important points of geological theory. "It exhibits very extraordinary instances of rocks broken in almost every direction, but principally from east to west, and filled with veins again broken in, diversified by cross lines, and filled with other veins, and exhibiting marks of various successive phenomena of this kind.

"Respecting the agents that produced the chasms in the primary strata, and the power by which they were filled with stony and metallic matter, it would be easy to speculate, but very difficult to reason by legitimate philosophical induction."

In the concluding passage, however, he very freely admits his preference for the doctrine of fire.

"It is amongst extinct volcanoes, the surfaces of which have been removed by the action of air and water, and in which the interior parts of strata of lavas are exposed, that the most instructive examples of the operation of slow cooling upon heated masses are to be found. It is difficult to conceive that water could have been the solvent of the different granitic and porphyritic formations; for, in that case, some combinations of water with the pure earths ought to be found in them. Quartz ought to exist in a state of _hydrate_, and Wavellite, not Corundum, ought to be the state of alumina in granite.

"To suppose the primary rocks, in general, to have been produced by the slow cooling of a mass formed by the combustion of the metallic bases of the earths, appears to me the most reasonable hypothesis; yet aqueous agency must not be entirely excluded from our geological views. In many cases of crystallization, even in volcanic countries, this cause operates; thus in Ischia, siliceous _tufas_ are formed from hot springs; and in the lake Albula, or the lake of Solfaterra, near Tivoli, crystals of calcareous spar and of sulphur separate from water impregnated with carbonic acid and hepatic gas; and large strata of calcareous rocks, formed evidently in late times by water impregnated with carbonic acid, exist in various parts of Europe. The Travertine marble (_Marmor Tiburtinum_) is a production of this kind; and it is of this species of stone that the Colosseum at Rome, and the cathedral of St. Peter, are built. It is likewise employed in the ancient temple of Pæstum, and it rivals in durability, if not in beauty, the primary marble of Paris and Carrara."