A Welsh coal miner's safety lamp. The safety lamp evolved from a need to prevent the numerous fatal mining accidents of the late eighteenth century that were caused by explosions of methane/air mixtures ignited by the flames of miners' candles. Sir Humphrey Davy's original design was a simple oil burner enclosed in wire gauze cylinder. The heat of the flame was effectively contained by conduction through the wires of the gauze, whose temperature never rose to the ignition point of the methane/air mixture. A later modification (shown here) possessed a thick glass window around the flame and a brass shroud surrounding the upper gauze to protect it from damage.