Dangers of the Mine, 145 



and crush him ; sometimes the choke-damp 

 (coal-gas, or carbonic acid) comes and chokes 

 him to death ; and sometimes the " fire-damp " 

 (explosive gas) comes, and blows him like a 

 bullet along the gallery or up the shaft, and 

 sometimes it is strong enough to blow the 

 mine to pieces, shattering the steam-engine 

 and breaking into little sticks the house that 

 covers it. 



3. Sir Humphry Davy, who was once a poor boy, in- 

 vented a safety-lamp for the miners. He surrounded a 

 common lamp with fine wire gauze,"so that the flame could 

 not get through it to set fire to the explosive gas ; yet, 

 strange to say, the gas will go through the wire gauze and 

 burn quietly in the lamp, thus helping the miner by giving 

 him light instead of blowing him to pieces. 



4. This fire-damp that kills these miners is pretty much 

 the same as the gas that burns so quietly in our houses (be- 

 ing carbureted hydrogen mixed with some olenant gas). 

 If, when ordinary gas (carbureted hydrogen) has been leak- 

 ing to a certain extent in a room, any person enters that 

 room with a lighted candle, just such an explosion takes 

 place in that room as at the bottom of a mine. Explo- 

 sions in mines happen every year in this country, especi- 

 ally in Pennsylvania, also in England and Wales, 

 and many persons have been thus injured. 



5. It is curious to get into one of these 

 big coal-buckets and be lowered down to the 

 bottom of the shaft. What seemed from the 

 top to be like little stars or glow-worms moving 

 about below, turn out to be little lamps fast- 



