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Davy's Safety Lamp
From: Science Museum
| By:
Jane Kirk |
EDITOR'S INTRODUCTION |
Sir Humphry Davy's famous legacy is the safety lamp--an invention which transformed mining practices in the early nineteenth century. Before this time, miners worked by the light of naked flames and large numbers lost their lives in explosions when the flames ignited firedamp, a gas found in the coal seams. Unfortunately Davy's lamp did not actually reduce the numbers of accidents and fatalities, but it did allow the exploitation of deeper mines. Jane Kirk, former registrar at the Science Museum, tells the story of the first safety lamp ever used in a coal mine. |
 hese lamps, designed by Sir Humphry Davy (1778-1829) are said to be the first safety lamps actually used in a coal mine. |
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| Sir Humphry Davy (1778-1829) | |
In the eighteenth century miners worked by the light of candles or other naked flames. As mines became deeper a new hazard appeared--firedamp. This is a gas, composed mainly of methane, produced by the decomposition of vegetable matter when coal seams are formed and retained in fissures and molecular interstices. The gas is not poisonous but when mixed with air in certain proportions it is explosive and can be ignited by a naked flame. |
An increasing number of miners lost their lives in these pit explosions and several attempts were made to develop a lamp that would be safe underground. Carlisle Spedding (c. 1696-1755) invented a steel and flint mill where light was obtained in the form of a stream of sparks created by rotating a thin steel disc against flint. This was quite widely adopted in the north of England and was safer than a candle. However, explosions still occurred and a boy was needed to operate it so it was expensive. |
On 28 May 1812 an explosion at Felling Colliery killed 92 men and boys. The publicity given to it by the vicar of the parish, the Reverend John Hodgson, resulted in the establishment, on 1 October 1813, of the Sunderland Society for Preventing Accidents in Coal Mines. The Society approached Sir Humphry Davy for help. Davy met John Hodgson and John Buddle, the leading mining engineer of the day, and visited Hebbum Colliery where he carried out some experiments. After Davy returned to London Hodgson sent him some firedamp in six wine bottles and shortly afterwards Davy wrote, |
I have already discovered that explosive mixtures of mine damp will not pass through small apertures or tubes; and that if a lamp, or lanthorn be made air tight on the sides, and furnished with apertures to admit the air, it will not communicate flame to the outward atmosphere. |
 Subsequently on 9 November Davy read a paper to the Royal Society entitled 'On the firedamp of coal mines and on methods of lighting the mines so as to prevent its explosion'. Three lamps were described in the paper. They were glass lanterns but with the air feed through concentric metal cylinders or, in one case, through wire gauze. The top of the glass chimneys was similarly equipped. By this time he had discovered the principle on which the safety lamp was to be constructed but it was another month or so before he conceived the idea of surrounding the flame of the lamp with wire gauze. |
The first Davy safety lamps were complete at the end of 1815 or early 1816 and sent to John Buddle. They were tested in Hebbum Colliery on 9 and 17 January. John Buddle recorded his reactions: |
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'. |
Each lamp has a cylinder of brass wire gauze of one and a half inches in diameter and five inches high screwed to the top of a reservoir of oil. In one there is also a spout for filling the vessel and a pricker to trim the wick. |
Davy was well aware that in certain circumstances, such as a strong current of firedamp, his lamp could be unsafe and he himself suggested some modifications. These included a gauze cap over the top of the main gauze to cool the burnt gases and a tin shield sliding on the frame wires of the lamp to protect it from draughts. |
 The Davy lamp was widely adopted and over the years many modifications and improvements were made. Davy was awarded a service of silver plate valued at £2,500 in recompense for his efforts. Unfortunately, the Davy lamp did not reduce the number of accidents and fatalities: it merely allowed deeper and less safe mines to be exploited. |
At about the same time as Davy was engaged in his experiments, George Stephenson (1781-1848) was working on a safety lamp also based on the principle of explosive gases not passing through small tubes and apertures. There arose considerable controversy, never fully resolved, about whose was the first safety lamp. In practice Davy's lamp was far more significant because it was his understanding of the scientific principles and application of the wire gauze that was so valuable and which formed the basis for the design of virtually all flame safety lamps. Indeed Stephenson also soon adopted a wire gauze for his lamps. |
In 1830, John Hodgson gave these early Davy lamps to a friend by whom they were presented to the Museum of Practical Geology. They were transferred to the Science Museum in 1895. |
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