"A safety lamp is any of several types of lamp that provides illumination in coal mines and is designed to operate in air that may contain ...
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coal dust or gases, both of which are potentially flammable or explosive. Until the development of effective electric lamps in the early 1900s, miners used flame lamps to provide illumination. Open flame lamps could ignite flammable gases which collected in mines, causing explosions; safety lamps were developed to enclose the flame and prevent it from igniting the surrounding atmosphere. Flame safety lamps have been replaced in mining with sealed explosion-proof electric lights." - (en.wikipedia.org 09.08.2021)
