626 
realizing the security and convenience so necessary to be 
attained. 
It is scarcely necessary to incorporate in this paper, a dis- 
cussion of the details of particular systems, resorted to in the 
merely mechanical operation of getting coal. They are to a 
great extent, quite independent of the scheme, and theory, 
upon which the ventilation of the mine is established. Assum- 
ing them, therefore, as applicable to one direction or the other, 
it must be evident, that the most active and important facili- 
ties may be obtained, by allying them to current^ which 
follow an ascending plane, and that all such advantages are 
frustrated, when the isolation is produced, which descending 
currents of necessity give rise to. 
Without wishing to diminish the censure sought to be 
stamped on what may be termed the unnatural or downward 
direction of ventilating currents, for the operative parts of a 
mine, there may be sufficient to justify in practice, the adop- 
tion of a descending plane for the final course, by which the 
return air is directly expelled from the mine. The operation 
of coal-getting should, however, be so manipulated, as that 
each separate working "face" should have access to the 
return air-course at the highest point to which the face may 
be carried ; the fresh, air admitted at the lowest part, being 
made to sweep out the goaf in its passage to the face, and so 
prevent the accumulation of secreted gas, in places to which 
it is attracted by repose, rather than habit or natural choice. 
The vast importance of improved systems of ventilation, 
might be urged as a necessity of winning coal from far 
greater depths than we have hitherto been accustomed to; 
the proposition is, however, too self-evident to warrant 
further observation. 
The events of the present moment in connection with the 
recent explosion, and the recovery now in progress of the vast 
multitude who perished at the Oaks Colliery in December 
