Coal mine, 1908. Miners sitting on a railroad engine in a coal mine. They are carrying Davy safety lamps. The Davy lamp was invented in 1815 by Sir Humphrey Davy to prevent explosions in coal mines caused by pockets of methane gas and naked flames. The Davy lamp's flame is enclosed in a metal gauze that distributes the flame's heat over a large area. This prevents the temperature from the flame reaching the ignition temperature of methane. Photographed in Gary mine, Gary, West Virginia, USA.