Davy lamp

In 1815 Humphry Davy devised a safety lamp for use in coal mines, allowing deep seams to be mined despite the presence of methane and other flammable gases, called firedamp or minedamp.

He had discovered that, to explode, the gas must be heated to its ignition temperature and that if such heating is prevented combustion cannot occur. If the flame in a lamp is surrounded by metal gauze to distribute the heat over a large area, the maximum temperature of the screen is below the ignition temperature of the gas. The first trial of a Davy lamp with a wire sieve was at Hebburn Colliery on January 9, 1816.

The lamp also provided a crude test for the presence of gases. If inflammable gas mixtures were present, the flame of the Davy lamp burned higher with a blue tinge. Miners could also place a 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, the lamp flame would be extinguished (chokedamp).

There was some controversy, since George Stephenson also produced a similar safety lamp in 1815.