n such cases will
render the dust innocuous. The dust is extremely fine, and is easily
carried into every nook and crevice, and when, as at Bridgend in 1892, it
explodes, it is driven up and out of the shaft, enveloping everything
temporarily in dust and darkness.

In some of the pits in South Wales a system of fine sprays of water is in
use, by which the water is ejected from pin-holes pricked in a series of
pipes which are carried through the workings. A fine mist is thus caused
where necessary, which is carried forward by the force of the ventilating
current.

A thorough system of inspection in coal-mines throughout the world is
undoubtedly urgently called for, in order to ensure the proper carrying
out of the various regulations framed for their safety. It is extremely
unfortunate that so many of the accidents which happen are preventable,
if only men of knowledge and of scientific attainments filled the
responsible positions of the overlookers.

CHAPTER V.

EARLY HISTORY--ITS USE AND ITS ABUSE.

The extensive use of coal throughout the civilised world for purposes of
heating and illumination, and for the carrying on of manufactures and
industries, may be regarded as a well-marked characteristic of the age in
which we live.

Coal must have been in centuries past a familiar object to many
generations. People must have long been living in close proximity to its
outcrops at the sides of the mountains and at the surface of the land,
yet without being acquainted with its practical value, and it seems
strange that so little use was made of it until about three centuries
ago, and that its use did not spread earlier and more quickly throughout
civilised countries.

A mineral fuel is mentioned by Theophrastus about 300 B.C., from which it
is inferred that thus early it was dug from some of the more shallow
depths. The Britons before the time of the Roman invasion are credited
with some slight knowledge of its industrial value. Prehistoric
excavations have been found in Monmouthshire, and at Stanley, in
Derbyshire, and the flint axes there actually found imbedded in the layer
of coal are reasonably held to indicate its excavation by neolithic or
palaeolithic (stone-age) workmen.

The fact that coal cinders have been found on old Roman walls in
conjunction with Roman tools and implements, goes to prove that its use,
at least for heating purposes, was known in England prior to the Saxon
invasion, whilst some