of this regulation in each and every pit necessarily devolves
on the managers, many of whom in the absence of an inspector leave the
requirement a dead letter. Every improvement which results in the better
ventilation of a coal-mine tends to leave the dust in a more dangerous
condition. The air, as it descends the shaft and permeates the workings,
becomes more and more heated, and licks up every particle of moisture it
can touch. Thorough ventilation results in more greatly freeing a mine of
the dangerous fire-damp, but the remedy brings about another disease,
viz., the drying-up of all moisture. The dust is thus left in a
dangerously inflammable condition, acting like a train of gunpowder, to
be started, it may be, by the slightest breath of an explosion. There is
apparently little doubt that the presence of coal-dust in a dry state in
a mine appreciably increases the liability of explosion in that mine.

So far as Great Britain is concerned, a Royal Commission was appointed by
Lord Rosebery's Government to inquire into and investigate the facts
referring to coal-dust. Generally speaking, the conclusion arrived at was
that fine coal-dust was inflammable under certain conditions. There was
considerable difference of opinion as to what these conditions were. Some
were of opinion that coal-dust and air alone were of an explosive nature,
whilst others thought that alone they were not, but that the addition of
a small quantity of fire-damp rendered the mixture explosive. An
important conclusion was come to, that, with the combustion of coal-dust
alone, there was little or no concussion, and that the flame was not of
an explosive character.

Coal-dust was, however, admittedly dangerous, especially if in a dry
condition. The effects of an explosion of gas might be considerably
extended by its presence, and there seems every reason to believe that,
with a suitable admixture of air and a very small proportion of gas, it
forms a dangerous explosive. Legislation in the direction of the report
of the Commission is urgently needed.

We have seen elsewhere what it is in the dust which makes it dangerous,
how that, for the most part, it consists of the dust-like spores of the
_lepidodendron_ tree, fine and impalpable as the spores on the backs of
some of our living ferns, and the fact that this consists of a large
proportion of resin makes it the easily inflammable substance it is.
Nothing but an incessant watering of the workings i