"The heroic is for hereafter... for labors of pick and spade by Davy lamp down below."
George Meredith, The Amazing Marriage (1895)
Miners' safety lamps are still referred to generically as "Davy lamps," after Sir Humphry Davy (1778-1829) who pioneered their design. He was not, however, alone in this endeavor. At the same time as Davy was developing his lamp, railway pioneer George Stephenson and Dr. William R. Clanny were also designing a lamp for miners.
The invention of the miner's lamp allowed for penetration to deeper mining seams, by providing light, albeit dim. More importantly, the lamp also gave an indication of the presence of flammable gases such as methane, by its flame burning suddenly more brightly with a blue tinge. It also indicated areas where oxygen was low, by the flame simply extinguishing, and so also functioned as a safety device.
The greatest design problem was to create a light that would not cause an explosion in the proximity of flammable gases. Through experiments Davy realized that flammable gases would only explode if they were heated to their igniting temperature, so he devised a wire mesh to enclose the flame in his lamp. The wire absorbed the heat from the flame, spreading it over a large area and so keeping the temperature below the level at which the gases would ignite. Although Davy's lamp did not give off much light due to the surrounding wire mesh, it did cut down greatly on the number of explosions, and his wire mesh system was used effectively for a hundred years or more.
By around 1900 electric lamps had started to be used, and by the 1930s they had all but replaced the original open-flame lamp, providing more light and being much safer. Despite this, the original Davy lamps continued to be used to determine the presence of gases and levels of oxygen, rather than for their lightgiving properties.
