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
Tensor lamp Tensor lamp Tensor lamp is a small high-intensity and low-voltage desk lamp invented by Jay Monroe. The lamp was mainly popular during the 1960s and 1970s. The lamp was originally used by doctors and dentists, and later became more widely used. The first Tensor lamp consisted of assembling together a 12-volt automobile parking light bulb and reflector made from an ordinary kitchen measuring cup. Monroe fixed the cup to a metal tube that was attached to a transformer, which reduced 115-volt house current to 12 volts. Because of the small bulb, the entire lamp could be made smaller with a