Brief History of the Miner's Flame Safety Lamp
While the introduction of the steam engine for dewatering and hoisting had led to the deepening of the collieries in England, the ventilation technology to control the increased dangers of methane fell behind. In the early 1800's, several large colliery explosions in the North of England had killed many pit men. Attention was called for the need of a flame lamp that would not ignite "firedamp".
Although there is a dispute to who invented the "first" miner's flame lamp that was safe to use in fiery mines, the success of the flame safety lamp was a culmination of the principles discovered by Dr. William R. Clanny, Sir Humphrey Davy, and George Stephenson. All three men worked independently on the problem at about the same time, and all had some knowledge of the other's work.
The principle of isolating the flame of the lamp was evolved by Dr. Clanny in 1813. Clanny's first lamp designs involved enclosing the flame, and pressurizing the lamp via bellows that would use water reservoirs to isolate the flame. The lamp was rather clumsy, and saw no practical use in the mines. But the feature of a glass window would be later a common feature on safety lamps.
At about the same time, Sir Humphrey Davy was performing several experiments of his own for the development of a safety lamp. In 1815, Davy discovered that if two vessels were filled with explosive gas, they might be connected together by a narrow tube, and the gas in one of the chambers could be exploded without transmitting the explosion to the adjoining chamber. This meant that a flame in a lamp, fed mine air through small orifices, would not ignite the surrounding air of the mine.
Davy's further experiments found that mesh-holes of fine metallic gauze acted the same way as narrow tubes. The adjacent drawing depicts Davy's principle utilizing a Bunsen-burner. The flame will burn on one side of the gauze without igniting the gas on the under side of the gauze. This is because the gauze will dissipate heat fast enough that the temperature of the gas beneath is unable to rise to the point of ignition.
Davy built a lamp that totally enclosed the flame with a cylinder of gauze. While it did not give off much light, it was success in minimizing, although not eliminating, explosions from flame lamps. Davy's wire gauze principle was used in almost every type of flame safety lamp that was developed for near 200 years.
While Clanny and Davy were working on their safety lamps, George Stephenson (who would later go on to invent the steam locomotive) was working on his safety lamp. In 1815 , Stephenson was an enginewright at the Killingworth colliery near New Castle. Stephenson started developing and testing lamps designed on 2 principles: 1)"burnt air" (carbonic gas, CO2) would prevent transmission of explosions. 2) The velocity of burning firedamp was slow. So, if an air draft opposite to the direction of combustion of great enough velocity could be created, transmission of explosion would not occur. Stephenson's third lamp was a success, and with modifications was successfully used in coal mines mainly in the North of England.
There has been a long dispute to as who really invented the first "safety lamp". Clanny, Davy, and Stephenson each contributed to the evolution of the safety lamp. To summarize their contributions:
Dr. Clanny- Separated the flame from the mine's firedamp atmosphere.
Sir Humphrey Davy- Enclosed the flame in a wire gauze.
George Stephenson- Leave space above the flame for "burnt air".
Clanny eventually incorporated Davy's wire gauze.
Stephenson eventually incorporated Davy's wire gauze in his famous "Geordie" lamp.
The overpowering element that perpetrated almost all flame safety lamp designs was Davy's wire gauze. In fact, Clanny and Stephenson eventually incorporated Davy's wire gauze in their design. This is why, even to this day, a miner's flame safety lamp has generically been called a "Davy Lamp".
Early on in the development of the flame safety lamp, it was realized that it could be used for gas measuring purposes. Eventually, many lamps where developed for the sole purpose of measuring the amount of methane in a mine atmosphere. Thus, safety lamps where categorized as either for lighting or gas measuring.
The safety lamp started to be replaced with electric mine lighting devices after 1900. By 1930 or so, almost all flame safety lamps were replaced by electric lamps. But, safety lamps still continued to be use for detecting and measuring gas long after their use for lighting was obsolete.
The Miner's Flame Light Book, Henry Pohs, 1995, Flame Publishing Company.