567 
The task of ventilation, if it had reference only to the 
supply of fresh air to the workpeople engaged in the mine, 
would become one of the simplest character, and would 
scarcely continue to be one beyond the reach of the most 
ordinary capacity to deal with it. 
Besides contributing the vital element of respiration to the 
workmen, however, ventilation also embraces the removal of 
gases given out by the coal, and other strata exposed in the 
mine, and which, if not removed, are by their presence and 
accumulation ever surrounding the entire operations with 
danger and death. 
Of the general character of the most important gas exuded 
from coal strata, known familiarly as fire-damp, or the carbu- 
retted hydrogen of chemistry, but little need be said. Its 
specific gravity, slightly more than half the weight of atmos- 
pheric air, renders it under certain conditions, peculiarly easy 
of removal by ventilation, although under other conditions, 
and those perhaps most commonly found in practice, this 
quality of lightness increases the difficulty with which it is 
expelled from the mine. Nature, however, in which we trace 
such inexhaustible evidences of Providential arrangement and 
design, has given another peculiarity to this gas, as if to 
stimulate the ingenuity of man, in providing for its effectual 
escape from the place where its presence might originate such 
fearful disaster and distress. It has neither colour nor smell, 
and hence may exist in the most dangerous proximity, without 
attracting the notice of the workman by whose light it may be 
instantly ignited, carrying ruin and death by its explosion, to 
every part of the mine. Surely we recognise in these pecu- 
liarities, admonitions, as of Providence, warning us of the kind 
of arrangements we ought to provide, in order to the free and 
voluntary exit of an agent, whose habit would be to escape 
from our presence rather than linger to our peril, if the con- 
ditions were not opposed to its retreat, which almost univer- 
