ast. The latter, where the coals are drawn
up to the surface, are in the lowest part of the mine, and all the
passages are on a gentle ascent towards the furnace, so that the air
down the shafts is drawn that way. The furnace consists of a number of
iron bars placed horizontally across the end of a large brick arch, and
the roof and sides are built of the best fired bricks. On the iron bars
nearly a ton of coals is kept constantly burning and throws out a great
heat, relays of men being employed in replenishing it. At the back of
the furnace is a shaft to carry off the smoke. Thus the cool air
circulates all over the mine. When a large supply of air is required in
any particular part of the mine, the doors are closed at the entrance to
the other parts, thus directing the current where it is most wanted.
This current is so strong that on opening one of these doors, care is
necessary in shutting it, as it would slam with a force sufficient to
knock a man down.

These and other arrangements, and the vast amount of machinery now
employed, had not, however, been introduced when Mark Gilbart began life
as a "trapper." The most dangerous operation is the opening of a new
passage, from which foul air may suddenly escape and poison the miners
inhaling it, or a stream of water may rush forth, rilling up the
gallery, and drowning all within its reach. Numberless, indeed, are the
dangers to which miners are exposed. Their condition is now improved,
but they formerly worked eleven or twelve hours a-day, and occasionally
even from thirteen to sixteen, far down in the depths of the earth, in a
heavy and noxious atmosphere, in a half naked state and in unnatural
positions, kneeling, stooping, lying upon their sides and backs, at any
moment liable to the loss of life. The miner has not only to undergo
bodily labour, but must exercise skill, patience, presence of mind,
coolness, and thoughtfulness. Countless, also, are the dangers to which
they are exposed. To accidents as they come down or go up the shafts by
the breaking of ropes, or the giving way of machinery, from the falling
in of the roof or walls, as also from accidents in blasting, from
spontaneous combustion, from explosion of fire-damp, suffocation from
choke-damp, and eruptions of water, and even quicksands. Sometimes
floods or heavy rains find their way down unknown crevices into the pit,
where the miner is working, and forming a rapid torrent, suddenly
inundate