Safety lamp was a lamp designed to warn coal miners of the presence of firedamp, a gas that can cause destructive mine explosions. Firedamp is composed chiefly of methane and air. It is colorless and odorless. The methane forms when plants decay during the coal-forming process. Coal-mining operations can release firedamp.
The safety lamp burned oil. Inside the lamp, a wire gauze cylinder of fine mesh formed a cage around the flame. Firedamp could be detected by lowering the wick on the lamp. If firedamp was present, a pale blue flame would appear around the central flame. This blue flame warned a miner to leave that part of the mine immediately.
The heat of the flame would not pass beyond the gauze covering and light the gas on the outside until the wire became as hot as the flame. The wire around the miner’s safety lamp had good conducting power and would not heat up before the miner had time to escape. Most safety lamps were locked to prevent miners from opening them. Some of the lamps went out when they were opened.
The safety lamp, also known as the Davy lamp, was based on a principle discovered by the English chemist Sir Humphry Davy. He made the first successful safety lamp in 1815. Electronic gas detectors have largely replaced safety lamps in mines.
