The Davy lamp was invented in 1815 by Sir Humphry Davy as a safe source of light in coal mines that were prone to explosions due to the presence of flammable gases. His lamp also served as a gas detector, ironically leading to more coalmine explosions. Another safety light, the Geordie lamp, was introduced in 1816, sparking a debate about which lamp was safer and more effective. A modern version of the Davy lamp is still used in modern coal mines.
Davy discovered that the gases found in coal mines, called firedamp or minedamp, would not be ignited by a lamp whose flame was contained within a fine wire mesh. The mesh screen surrounding the Davy lamp's flame allowed air to pass through to support combustion while preventing the lamp from igniting the firedamp. Miners also used the Davy lamp as a gas detector; in the presence of flammable gases, the lamp's flame grew in height and became more blue. The Davy lamp was also used to signal a lack of oxygen, as its flame would extinguish before the lack of oxygen posed a threat to miners.
An increase in coal mine explosions occurred following the introduction of the Davy lamp. This was in part due to owners mining areas previously abandoned due to safety concerns. The wire mesh used in the lamps was prone to rust and breakage, permitting an explosion, so the lamps tended to create a false sense of security. They also served to delay the introduction of more expensive ventilation measures.
A similar safety lamp developed by George Stephenson and introduced in 1816 caused some debate among miners about which design was more effective. Critics of the Geordie lamp, as it was called, maintained that if the glass tube surrounding its mesh and flame was broken, it would cause an explosion. Geordie lamp supporters pointed to the fact that a single broken or missing wire in the Davy lamp would ignite firedamp. The reality was both designs had significant flaws that were not completely resolved until the introduction of electric lamps.
A descendant of the Davy lamp, called the Protector Garforth GR6s safety lamp, is still required in coalmines throughout the United Kingdom. Although it is only used as an adjunct to more sophisticated electronic gas-detection devices in modern coalmines, the lamp's essential design has been put to new uses. The Olympic Games flame is also relayed using a modified version of the Davy design.