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sally ally themselves to the systems of winning coal, now 
practised in this country. 
Released as this gas is, by the continual getting and break- 
ing down of the coal, and by the exposure of innumerable 
fissures and openings, through which it discharges itself from 
the strata into the mine, its natural and irresistible tendency 
is to lodge in the most elevated cavities which can be found 
for its reception, — and hence a powerful opposition is exerted 
by its own specific gravity to any channel of escape, which 
does not present the features of an ascending plane. And 
here we meet the grand parent of all our difficulties, and 
perhaps of all our woes. For the system of laying out 
collieries, now most commonly acted upon, by placing the 
down-cast and up-cast shafts in near proximity to each other, 
gives, after the works have been a short time in operation, a 
descending rather than an ascending way of escape, which 
the explosive gas or fire-damp is made to pursue (so far as its 
escape is effected at all), by being united in the air supplied 
from the surface for the respiratory and ventilating require- 
ments of the miners, and of the Limbo of their arduous toil. 
Beyond that which escapes along the return-air-courses, 
there is necessarily in every mine a considerable generation 
of gas, which exudes at places where no admixture with the 
return-air can take place ; and this gas, with portions which 
escape admixture, even in the air-courses themselves, goes to 
furnish the supply, which, lodging in the " goafs" or places 
from which the coal has been exhausted, and in other parts 
of the mine, creates and perpetuates a magazine of explosive 
element, almost too fearful to contemplate. 
It is not intended here to allege that a state of things, of 
which this statement affords a picture, obtains in all collieries, 
even of this district ; or that abstraction of explosive gases, 
or fire-damp is impossible, or may not be effected, both from 
the " goafs " and other parts of the mine, along descending 
