594 
3rd. That a continuously ascending ventilation towards 
the furnace and up-cast pit is not only practicable, but is the 
only means by which the light inflammable gases can be 
expelled from a mine so as to render it safe. 
These are the general principles of the mode of working 
and ventilating coal mines that I recommend. The first 
thing to be considered in opening a new colliery is the posi- 
tion of the pits — the engine, the drawing, and up-cast pits — 
in relation to each other, and with reference to the field of 
coal to be laid dry and wrought by them. The engine pit 
will of course be sunk at or near the lowest point of the 
coal field ; and generally, unless obstructed by the locality 
or formation of the surface, it will be found most convenient 
to have the drawing pit within a short distance to the rise of 
the engine pit. Until the colliery is fully opened, and the 
up-cast pit sunk, the engine pit will serve as a down-cast and 
the drawing pit as an up-cast ; but afterwards, when fully 
opened, and the ventilation through the up-cast pit complete, 
they should both be used as down-cast pits. The up-cast pit 
should be sunk, and the ventilating furnace placed at the 
highest part of the field of coal to be drained and wrought 
by means of these pits, engine, and plant. The next step 
is to drive the working, water, and counter levels, and 
consecutively the double board-gates, first the pit board 
and the north back board, and the double cross headings 
up to the furnace and up-cast pit, and then the other board- 
gates set out at such distances from each other as the 
convenient hurrying of the coal, the nature of the roof, 
or other circumstances may require. In the sketch I have 
prepared, the board-gates are set out 120 yards apart, they 
are each yards wide, and the pillar of coal betwixt them 
16 yards wide. As soon as the levels, the pit board, the 
cross heading's, the back boards and two of the others, the 
up-cast pit and furnace, are constructed, the ventilation will be 
