en 1100 miners were killed. A somewhat similar
apparatus called the "weg," after the initials of the inventor, is due
to W. E. Garforth of Wakefield. In another form of apparatus advantage
is taken of the property possessed by sodium-potassium peroxide of
giving off oxygen when damped; the residue of caustic soda and potash
yielded by the reaction is used to absorb the carbonic acid of the
expired air. Experiments have also been made with a device in which the
air-supply is obtained by the evaporation of liquid air absorbed in
asbestos.

Underground fires are not uncommon accidents in coal-mines. In the thick
coal workings in South Staffordshire the slack left behind in the sides
of work is especially liable to fire from so-called spontaneous
combustion, due to the rapid oxidization that is set up when finely
divided coal is brought in contact with air. The best remedy in such
cases is to prevent the air from gaining access to the coal by building
a wall round the burning portion, which can in this way be isolated from
the remainder of the working, and the fire prevented from spreading,
even if it cannot be extinguished. When the coal is fired by the blast
of an explosion it is often necessary to isolate the mine completely by
stopping up the mouths of the pits with earth, or in extreme cases it
must be flooded with water or carbonic acid before the fire can be
brought under. There have been several instances of this being done in
the fiery pits in the Barnsley district, notably at the great explosion
at the Oaks colliery in 1866, when 360 lives were lost.

Methods of winding.

The drawing or winding of the coal from the pit bottom to the surface is
one of the most important operations in coal mining, and probably the
department in which mechanical appliances have been brought to the
highest state of development.

Cage.

The different elements making up the drawing arrangements of a colliery
are--(1) the cage, (2) the shaft or pit fittings, (3) the drawing-rope,
(4) the engine and (5) the surface arrangements. The cage, as its name
implies, consists of one or more platforms connected by an open
framework of vertical bars of wrought iron or steel, with a top bar to
which the drawing-rope is attached. It is customary to have a curved
sheet iron roof or bonnet when the cage is used for raising or lowering
the miners, to protect them from injury by falling materials. The number
of platforms or decks varies con