Gas detector early detection methods relied on less precise detectors. Through the 19th and early 20th centuries, coal miners would bring canaries down to the tunnels with them as an early detection system against life-threatening gases such as carbon dioxide, carbon monoxide and methane. The canary, normally a very songful bird, would stop singing and eventually die if not removed from these gases, signaling the miners to exit the mine quickly. The first gas detector in the industrial age was the "flame safety lamp" (or Davy lamp) was invented by Sir Humphry Davy (of England) in 1815 to detect the presence of
Safety lamp was surrounded by gauze so that in the event of a glass breakage the Geordie became a Davy. If the current of air forced in through the tubes (later holes and gallery) by the lamp's situation was too strong, the flame grew, and the lamp could get red-hot. The lamp becomes unsafe in a current of from 8 to 12 feet per second, about twice the limit of the Davy's safe operating conditions. However, this variation in the flame was not entirely bad. The intensity of the flame, air currents being equal, gives an indication of firedamp levels, so it