History of chemistry iodine first, but both scientists acknowledged Courtois as the first to isolate the element. In 1815, Humphry Davy invented the Davy lamp, which allowed miners within coal mines to work safely in the presence of flammable gases. There had been many mining explosions caused by firedamp or methane often ignited by open flames of the lamps then used by miners. Davy conceived of using an iron gauze to enclose a lamp's flame, and so prevent the methane burning inside the lamp from passing out to the general atmosphere. Although the idea of the safety lamp had already been demonstrated by
Signal lamp lamps are still used today, as a backup device in case of a complete failure of an aircraft's radio. Light signals can be green, red, or white, and steady or flashing. Messages are limited to a handful of basic instructions (e.g., "land", "stop", etc.); they are not intended to be used for transmitting messages in Morse code. Aircraft can acknowledge signals by rocking their wings or flashing their landing lights. Signal lamp A signal lamp (sometimes called an Aldis lamp, after Arthur Cyril Webb Aldis who invented a widely used design, or a Morse lamp) is a visual signaling device