Safety lamp

Safety lamp, oil-burning lamp used in coal mines that indicates the presence of explosive methane gas without igniting it. Designed in 1815 by English chemist Sir Humphry Davy, it uses a double wire gauze cylinder to enclose the flame, preventing heat from escaping and causing an explosion. In the presence of firedamp, the methane-air mixture commonly released in coal mining operations, the flame burns with a blue center, warning miners to leave the mine immediately. The safety electric lamps now used to light mines are designed so that if the bulb is broken the current shuts off, thus preventing ignition of firedamp. But although electric lamps are safe, they do not indicate the presence of the gas, and Davy lamps are still used to warn miners of the danger.

See also: Mining.