The Age of Wonder (63 page)

The methane passed freely through the iron gauze to the naked flame inside the lamp, ignited there and burnt vividly. ‘The lower part of the flame is green, the middle purple, and the upper part blue.’ But it could not pass back at sufficient temperature to ignite and explode the firedamp outside in the mine. Even when the gauze became red hot, the flame would not pass through it. Moreover, provided the lamp was entirely enclosed in the iron gauze, it did not have to have an airtight glass chimney. It was much less vulnerable, and could be redesigned as a much cheaper and more robust instrument. Davy wrote dramatically of confining ‘this destructive element flame like a bird in a cage’.
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Holding an iron gauze over a Bunsen burner, and observing that, against all expectation, the flame does not pass through it, is now one of the elementary experiments performed in school chemistry classrooms. It is easy to forget how startling this effect is on seeing it for the first time.

The final version of the lamp was wonderfully simple and surprisingly small. It was a standard uninsulated oil lamp, approximately sixteen inches high, with an adjustable cotton wick, enclosed in a tall column or ‘chimney’ of fine iron mesh. Astonishingly, the lamp required no other protection. In later models Davy added various improvements, largely designed to withstand rough use in the mine.

Yet the fundamental notion that flame would not pass through gauze appeared so unlikely, so completely counter-intuitive, that Davy had to lay out the stages of his discovery with absolute clarity, step by step. The result was a new kind of scientific narrative. The uncertainty and false starts of the experimental laboratory disappeared. Faraday’s sketches showed that trial models had originally included a piston-bellows lamp, a spring-valve lamp and a hinged lamp, none of which was subsequently mentioned.
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Instead the account was transformed into a gripping, single-track narrative of progressive, seemingly inevitable, discovery.

In trying my first tube-lamp in an explosive mixture I found that it was safe; but unless the tubes were very short and numerous, the flame could not well be supported…I arrived at the conclusion that
a metallic tissue,
however thin and fine, of which the apertures filled more space than the cooling surface, so as to be permeable to air and light, offered a perfect barrier to explosion…In plunging a light surrounded by a cylinder of fine wire gauze into an explosive mixture I saw the whole cylinder become quietly and gradually filled with flame, the upper part of it soon appeared red hot; yet
no
explosion was produced…I immediately made a number of experiments to perfect this invention, which was evidently the one to be adopted…I placed my lighted lamps in a large glass receiver, and by means of a gasometer filled with coal gas, I made the current of air which passed into the lamp more or less explosive, and caused it to change rapidly or slowly at pleasure, so as to produce all possible varieties of inflammable and explosive mixtures: and I found that iron wire-gauze…was safe under all circumstances…and I consequently adopted this material in guarding lamps for the coal mines, where in January 1816, they were immediately adopted, and have long been in general use.
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When he republished the papers, Davy remarked: ‘Every step was furnished by experiment and induction, in which nothing can be said to be owing to accident, and in which the most simple and useful combination arose out of the most complicated circumstances.’
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In this way he insisted on the Baconian method of stage-by-stage, logical scientific induction, while tacitly admitting the existence of ‘complicated’ versions of the lamp which he had tried and rejected.

This refusal to allow anything to chance, ‘accident’ or good fortune was exactly the same as Herschel’s insistence that chance played no part in his discovery of Uranus. Coleridge had taken this up as one of the key philosophical problems associated with science, in an essay provokingly entitled ‘Does Fortune Favour Fools?’, which he republished in
The Friend
in 1818. Here he described Davy, perhaps mischievously, as ‘the illustrious Father and Founder of Philosophic Alchemy’. But he praised his great discoveries without reservation, and denied that his scientific research could ever have depended on ‘accident’ or ‘luck’. Yet this left him in a philosophical quandary: did that imply that ‘genius’ and ‘inspiration’ had no place in Davy’s science?
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The essay was originally written in 1809, in response to Davy’s work with the voltaic battery. Coleridge argued that Davy’s discoveries always depended on ‘preconcerted mediation…evolved out of his own intellect’, never on external accident. Davy’s scientific method was always conscious, skilful and deliberate, the fruit of deep knowledge and experience. But the essay raised other issues about scientific research. Coleridge’s way of describing the experimental process betrayed a certain uneasiness. Chemical experiments-using fire or electricity-contained a kind of violence. Davy’s aim was ‘to bind down material Nature under the Inquisition of Reason,
and force from her, as by torture,
unequivocal answers to prepared and preconceived questions’. Coleridge also wondered if scientific laws could ever truly ‘bind down’ all the phenomena of nature. Newtonian laws could define the phases of the moon, for instance, but could they ever define the movements and appearance of
clouds
? ‘The number and variety of their effects baffle our powers of calculation: and that the sky is clear or obscured at any particular time, we speak of, in common language, as a matter of
accident
’.
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5

The Davy Safety Lamp, the greatest public achievement of his career, would soon be in use all over Britain and Europe. The prototype gauzeenclosed lamp (’the Davy’) was presented to the Royal Society on 25 January 1816, after being successfully tested at Walls End, Hebburn and several other collieries that month.
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John Buddle, who had witnessed the full horror of several earlier explosions at Walls End, and understood the deep, suppressed fears of miners working in shafts 600 or 1,000 feet beneath the surface, never forgot his first trial with the new Davy Lamp. He later gave a verbatim account to a Parliamentary Committee: ‘On the strength of [Davy’s] authority I took this lamp, without hesitation, into an explosive mixture. I first tried it in an explosive mixture on the surface, and then took it into a mine; and to my astonishment and delight, it is impossible for me to express my feelings at the time when I first suspended the lamp in the mine, and saw it red hot; if it had been a monster destroyed, I could not have felt more exultation than I did. I said to those around me, “We have at last subdued this monster!” ’
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Davy went up to Northumberland in March to observe the lamps in action in the mines, and to work on refinements. These would include a platinum coil which relit the wick when it was extinguished by pure methane (’one of the most beautiful and magical experiments in the science of chemistry experiment’, remarked Faraday), tin draught shields, double gauze at the top of the chimney, and a reinforced open iron frame to protect the gauze if the lamp was struck or dropped.

He went down ‘G’ pit at Walls End, spent some two hours beneath the surface, and according to Buddle delivered an impromptu fifteen-minute lecture on using the lamp safely, stressing the need to avoid strong air currents or clouds of coal dust, which could still risk freak explosions. He also pointed out that the state of the flame indicated the presence, and even the strength, of fire-damp in a shaft. His lamp not only caged the flame, it transformed it into a canary.
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During this visit Davy received a deputation from the mine-owners, with a public letter of thanks describing his lamp as ‘a discovery unparalleled in the history of mining’. It was hoped that ‘this great and unrivalled discovery for preserving the lives of our fellow creatures, will be rewarded by some mark of national distinction’.
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Many individual miners also signed tributes or letters of thanks. In September 1816 ‘we, the undersigned miners at the Whitehaven Collieries’ thanked Davy for his ‘invaluable discovery of the safe lamps, which are to us life preservers’. They humbly wished it was in their power to offer more than this ‘tribute of gratitude’. The wording of the letter was obviously drawn up by an overseer, but the signatures were genuine, and must have moved Davy. The crumpled paper was laboriously signed by eighty-two miners, forty-seven of whom were illiterate, and put ‘x’ against their names.
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John Buddle, now entirely won over by Davy, was also concerned about a reward. By August there were 144 safety lamps ‘in daily use’ at Walls End, and they were rapidly spreading to all the other collieries in the North-East.
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Buddle urged Davy to take out a patent, pointing out that he could not only make his fortune but control the quality of the lamps issued to miners. Davy consistently refused, although he knew his colleague William Wollaston had made a fortune with a patent on processing platinum. Yet Davy was hugely proud of his achievement, and was never modest about it. On Banks’s recommendation he received the Rumford Medal from the Royal Society in 1817, and the following year was made a baronet by the Prince Regent. Davy designed his own coat of arms, showing the safety lamp encircled with a Latin motto which announced: ‘I Built the Light which brings Safety’.
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His reputation was now international. He received acknowledgements from miners in Alsace, Flanders, Austria and Poland. Some years later the Tsar of Russia, Alexander I, sent him a large silver goblet. At home the
Edinburgh Review
ran an enormous article in praise of his work, written by none other than the brilliant geologist who had once paid court to Jane Apreece, Professor John Playfair. ‘It may fairly be said that there is hardly in the whole compass of art or science a single invention of which one would rather wish to be the author.’ Playfair described the discovery as the result of pure inductive science, ‘in no degree the effect of accident’, and ‘as wonderful as it is important’. Its historic significance was unmistakeable. ‘This is exactly such a case as we should choose to place before Bacon, were he to revisit the earth, in order to give him, in a small compass, an idea of the advancement which philosophy has made, since the time when he pointed out to her the route which she ought to pursue.’ Here the word ‘philosophy’ was used exclusively to mean ‘science’ in the modern sense: what Playfair defined as ‘the immediate and constant appeal to experiment’.
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Davy published in 1818 a beautiful account of his discovery,
On the Safety Lamp for Coal Miners, with Some Researches into Flame.
Edited from the series of papers he had sent so hurriedly to the Royal Society, this has some claims to be one of the prose masterpieces of English Romanticism. Davy transformed his feverish, often chaotic work at the Royal Institution laboratory in the winter of 1815-16 into a classic piece of scientific storytelling. The prose is clear, pointed, and sometimes of poetical intensity.

The treatise begins with a dispassionate account of the terrible series of explosion accidents in the mines, the human suffering they had caused over decades, and the way they had terrorised the mining communities in the north of England: ‘The phenomena are always of the same kind. The miners are either immediately destroyed by the explosion, and thrown with the horses and machinery through the shaft into the air, the mine becoming as it were an enormous piece of artillery, from which they are projected; or they are gradually suffocated, and undergo a more painful death, from the carbonic acid and azote [nitrogen] remaining in the mine, after the inflammation of the firedamp; or what, though it appears the mildest, is perhaps the most severe fate, they are burnt or maimed, and often rendered incapable of labour, and of healthy enjoyment of life.’
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Davy then moves to the sequence of experiments he performed in the laboratory in London, producing a narrative as logical and thrilling as a detective story. He describes the previous work of Clanny and Humboldt, his experiences with Faraday in the Apennines,
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his assembling of his laboratory equipment, the meticulous process of chemical analysis (often highly dangerous), the varied appearances of slow flame and violent explosions, and the final triumphant sight of the prototype gauze lamp burning brightly and safely within the huge glass flask of lethal methane.

By relating the human predicament to the scientific solution, Davy produced one of the great demonstrations of scientific ‘Hope’. He showed that applied science could be a force for good previously unparalleled in human society, and might gradually liberate mankind from untold misery and suffering. Deliberately echoing Bacon-as Lavoisier had once done-he claimed that scientific knowledge was a disinterested power for good: ‘The results of these labours will, I trust, be useful to the cause of science, by proving that even the most apparently abstract philosophical truths may be connected with applications to the common wants and purposes of life. The gratification of the love of knowledge is delightful to every refined mind; but a much higher motive is offered in indulging it, when that knowledge is felt to be practical power, and when that power may be applied to lessen the miseries or increase the comforts of our fellow-creatures.’
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This would become the central credo of the next generation of young Victorian scientists, and notably of Michael Faraday.
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