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amount of unnecessary expense. All I consider necessary 
is to build a strong pillar opposite each of the slits from 
the board-gates through the narrow rim of coal left on each 
side of the banks to preserve the board-gates open. These 
pillars strengthen the rims and keep the slits open for 
ventilation. The pitmen are protected by strong stanchions 
of oak or cast iron, according to the nature of the roof and 
thickness of the seam — generally three rows, the third or 
back row being drawn out by a crane and chain as another 
front row is being set. The roof and overlaying strata 
gradually breaks or expands itself down, one fall towards 
the preceding, into the space from which the coal has been 
excavated. When the coal of the board-gate pillars and 
of the sixteen yard bank betwixt them is wrought out, it is 
in the same manner 44 down bank," — the gas being drained 
off, the ventilation, as in driving the 44 board-gates " is up 
one and down the other to the last. This mode of working 
greatly aids and simplifies the process of ventilation, because 
the course or stream of air is uniformly ascending con- 
currently with the natural impulse of the gas, as it is 
liberated from the coal, towards the furnace and up-cast pit, 
without any necessity of returning the current of air down 
the " banks" or 4 4 board-gates." And here I cannot abstain 
from remarking that the process of sending air up one side 
of a 44 bank" across the face and down the other side and 
at the same time through the goaves betwixt them, with the 
view of carrying off a light elastic gas, has always appeared 
to me to be alike contrary to science and the nature of things 
(I may add, it is many years since I heard an eminent 
mining engineer say it was alike contrary to science and to 
common sense), and I doubt that any mine containing gas 
ever was, by that mode of ventilating, rendered so safe but 
that, by a mistake or act of carelessness, it might have been 
at any time exploded. It could only be by forcing in such 
