methods of lighting the mines without producing its explosion. 19 
lighted in a part of the mine where there is no fire-damp, and 
by a person charged with the care of the lights : and by these 
inventions, used with such simple precautions, there is every 
reason to believe a number of lives will be saved, and much 
misery prevented. Where candles are employed in the open 
air in the mines, life is extinguished by the explosion ; with 
the safe lantern or safe lamp the light is only put out, and 
no other inconvenience will occur. 
It does not appear, by what I have learnt from the miners, 
that breathing, an atmosphere containing a certain mixture of 
fire-damp near or even at the explosive point, is attended with 
any bad consequence. I ascertained that a bird lived in a 
mixture of equal parts of fire-damp and air ; but he soon 
began to show symptoms of suffering. I found a slight head 
ache produced by breathing for a few minutes an explosive 
mixture of fire-damp and air : and if merely the health of 
the miners be considered, the fire-damp ought always to be 
kept far below the point of its explosive mixture. 
Miners sometimes are found alive in a mine after an explo- 
sion has taken place : this is easily explained, when it is 
considered that the inflammation is almost always limited to a 
particular spot, and that it mixes the residual air with much 
common air; and supposing 1 of fire-damp to 13 of air to be 
* exploded, there will still remain nearly ~ of the original quan- 
tity of oxygene in the residual gas : and in some experiments, 
made 16 years ago, I found that an animal lived though with 
suffering, for a short time, in a gas containing 100 parts of 
azote, 14 parts of carbonic acid, and 7 parts of oxygene. 
v 
