09/11/1815
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Explosion /
Methane Explosion
01 June 2015
Safety Underground:
Mining and the Miners’ Lamp
Professor Frank James
Towards the end of this year we will be marking the bicentenary of the simultaneous, and almost certainly independent, inventions of versions of the miners’ safety lamp by Humphry Davy and George Stephenson, and in 2016 the anniversary of its first deployment.
During the eighteenth century, the counties of Northumberland and Durham produced more coal than any other region in the British Isles. Even by the middle of the nineteenth century following the expansion of mining elsewhere, the north-east coal field still produced more than a fifth of the country’s coal. But such production came at a heavy cost to the lives of mineworkers. The opening years of the nineteenth century saw an exponential increase in coal mine fatalities caused by the explosion of what was then termed fire-damp, now known as methane (CH4). On 25 May 1812 ninety-two men and boys (including four aged under ten) were killed by an explosion at Felling colliery, near Gateshead. This was in the parish of Jarrow-with-Heworth, whose Rector, John Hodgson, was horrified at the loss of life, especially as virtually all the victims were buried in Heworth church.
One result of this disaster was the formation, in the autumn of 1813, of ‘A Society for preventing Accidents in Coal-Mines’, generally known as the Sunderland Society. The formation of this Society had been prompted by the Durham born London lawyer James Wilkinson who happened to be present at the time of the Felling explosion and had been appalled at the length of the funeral cortège. The former Whig MP for one of the County Durham seats and Lord Byron’s prospective father-in-law, Ralph Milbanke, was President of the Society in which the Rector of Bishopwearmouth, Robert Gray, played an active role. Its object to raise funds to provide premiums ‘for the discovery of new methods of lighting and ventilating mines’ was never realised. However, in early 1814 the Society issued its first report which argued that ‘it is to scientific men only that we must look up for assistance in providing a cheap and effectual remedy’.
Doubtless with this injunction in mind, Wilkinson called on Davy at the Royal Institution, which had been founded in 1799 with the practical remit of promoting ‘the application of science to the common purposes of life’, an agenda which Davy fully supported during his time at the institution. However, between late 1813 and early 1815 Davy was travelling on the Continent and the letter that Wilkinson subsequently wrote to him was returned as lacking sufficient postage. At a meeting of the Sunderland Society on 4 July 1815, chaired by Gray, who appears to have been ‘generally acquainted’ with Davy, it was resolved to approach him again about preventing explosions in mines. Gray’s letter has not been found, but judging by Davy’s reply sent from Melrose on 3 August 1815, he had asked Davy if there were any chemical means of destroying fire-damp. On his way south Davy spent some time in the north-east, collected sample of fire-damp which he had bottled and sent to London for future analysis.
During the week beginning 9 October, Davy, helped by the Royal Institution’s laboratory assistant, Michael Faraday, commenced an intense period of research on the problem. By the end of the month, Davy believed that he had developed a safe lamp which was basically a standard horn lamp with very narrow glass tubes acting as a chimney. He worked on the principle of endeavouring to construct a lamp which would allow light to pass, but would reduce the temperature of the heat reaching the surrounding atmosphere to below the point which would ignite the fire-damp. He told his patron, the President of the Royal Society of London, Joseph Banks, of his work for which Banks congratulated him heartily ‘on defending Society from a Tremendous Scourge of humanity’. With the same principle in mind Davy developed other lamps with a variety of chimney shapes (some with bimetallic valves) and lamps where their air was delivered by bellows, syringes or multiple narrow air intakes.
So confident was he of having achieved success that it was agreed his paper describing the lamps would be read to the Royal Society of London on 9 November and the prototype lamps were displayed in Banks’s Soho Square house. Although the figures for Davy’s paper were engraved (at some expense) for publication in the Philosophical Transactions, the paper as read was never published since Davy and Faraday continued work and soon developed the idea of what Davy called a fire sieve. This was a series of nested metal cylinders or rectangles, which would absorb the heat and thus reduce the external temperature of the lamp. From this it was only a short time before Davy realised that the same effect could be obtained by just using wire gauze, tell Hodgson right at the end of December:
When a candle or lamp is enclosed in a wire gauze cylinder & introduced into an explosive mixture the flame of the wick is extinguished but the mixed gas burns steadily within the wire gauze vessel. … I can confine this destructive element flame like a bird in a cage.
A few days later, Davy sent Hodgson five of his lamps on and 9 January 1816, Hodgson with others descended into Hebburn colliery (also in his parish) to test the lamps which was
entirely successful.