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Seventy six

There's a light that never goes out.

 

into the second decade of the 21st century, it is hard to see any evidence of the Kent coal industry. Snowdown colliery still stands, all behind fences and barbed wire and there is the truncated East Kent preserved railway.

 

Northbourne s near to Betteshanger, which was abandoned in August 1989.

 

This Davy Lamp hangs in the Chancel of St Augustine.

 

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Diagram of a Davy lamp

The Davy lamp is a safety lamp for use in flammable atmospheres, invented in 1815 by Sir Humphry Davy.[1] It consists of a wick lamp with the flame enclosed inside a mesh screen. It was created for use in coal mines, to reduce the danger of explosions due to the presence of methane and other flammable gases, called firedamp or minedamp.

 

Davy's invention was preceded by that of William Reid Clanny, an Irish doctor at Bishopwearmouth, who had read a paper to the Royal Society in May 1813. The more cumbersome Clanny safety lamp was successfully tested at Herrington Mill, and he won medals, from the Royal Society of Arts.[2]

 

Despite his lack of scientific knowledge, engine-wright George Stephenson devised a lamp in which the air entered via tiny holes, through which the flames of the lamp could not pass. A month before Davy presented his design to the Royal Society, Stephenson demonstrated his own lamp to two witnesses by taking it down Killingworth Colliery and holding it in front of a fissure from which firedamp was issuing.

 

The first trial of a Davy lamp with a wire sieve was at Hebburn Colliery on 9 January 1816.[3] A letter from Davy (which he intended to be kept private) describing his findings and various suggestions for a safety lamp was made public at a meeting in Newcastle on 3 November 1815,[4] and a paper describing the lamp was formally presented at a Royal Society meeting in London on 9 November.[5] For it, Davy was awarded the Society's Rumford Medal. Davy's lamp differed from Stephenson's in that the flame was surrounded by a screen of gauze, whereas Stephenson's prototype lamp had a perforated plate contained in a glass cylinder (a design mentioned in Davy's Royal Society paper as an alternative to his preferred solution).[5] For his invention Davy was given £2,000 worth of silver (the money being raised by public subscription), whilst Stephenson was accused of stealing the idea from Davy, because the fully developed 'Geordie lamp' had not been demonstrated by Stephenson until after Davy had presented his paper at the Royal Society and (it was held) previous versions had not actually been safe.[4][6][a]

 

A local committee of enquiry gathered in support of Stephenson exonerated him, showing that he had been working separately to create the Geordie lamp,[8] and raised a subscription for him of £1,000.[9] Davy and his supporters refused to accept their findings, and would not see how an uneducated man such as Stephenson could come up with the solution he had: Stephenson himself freely admitted that he had arrived at a practical solution on the basis of an erroneous theory.[9] In 1833 a House of Commons committee found that Stephenson had equal claim to having invented the safety lamp.[9] Davy went to his grave believing that Stephenson had stolen his idea. The Stephenson lamp was used almost exclusively in North East England, whereas the Davy lamp was used everywhere else. The experience gave Stephenson a lifelong distrust of London-based, theoretical, scientific experts

 

The lamp consists of a wick lamp with the flame enclosed inside a mesh screen. The screen acts as a flame arrestor; air (and any firedamp present) can pass through the mesh freely enough to support combustion, but the holes are too fine to allow a flame to propagate through them and ignite any firedamp outside the mesh. It originally burned a heavy vegetable oil.

 

The lamp also provided a test for the presence of gases. If flammable gas mixtures were present, the flame of the Davy lamp burned higher with a blue tinge. Lamps were equipped with a metal gauge to measure the height of the flame. Miners could place the safety lamp close to the ground to detect gases, such as carbon dioxide, that are denser than air and so could collect in depressions in the mine; if the mine air was oxygen-poor (asphyxiant gas), the lamp flame would be extinguished (black damp or chokedamp). A methane-air flame is extinguished at about 17% oxygen content (which will still support life), so the lamp gave an early indication of an unhealthy atmosphere, allowing the miners to get out before they died of asphyxiation.

 

en.wikipedia.org/wiki/Davy_lamp

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Uploaded on March 17, 2018
Taken on March 17, 2018