which registers the contents of the cylinders in atmospheres and minutes
of duration. The two cartridges used for absorbing the carbonic acid gas
are of no value after having been in use for two hours.

If inhalation is through the mouth alone, a mouthpiece is attached to
the end of the breathing tube by which the air or oxygen is supplied,
the nose is closed by a clip, and the eyes are protected by goggles. To
inhale through both nose and mouth, the miner wears a helmet or headgear
which can be made to fit tightly around the face. The helmet has two
tubes attached, one for inspiration and the other for expiration. In the
oxygen-cylinder apparatus these tubes lead to and from rubber sacks used
for pure-air and bad-air reserves.

Mine-Rescue Training.

It has been found in actual service that when a miner, equipped with
breathing apparatus for the first time, enters a mine in which an
explosion has occurred, he is soon overcome by excitement or nervousness
induced by the artificial conditions of breathing imposed by the
apparatus, the darkness and heat, and the consciousness that he is
surrounded with poisonous gases. It has also been found that a brief
period of training in the use of such apparatus, under conditions
simulating those encountered in a mine after a disaster, gives the miner
confidence and enables him to use the apparatus successfully under the
strain of the vigorous exertion incident to rescue work.

The rescue corps consists of five or six miners under the direction of
a mining engineer who is experienced in rescue operations and familiar
with the conditions existing after mine disasters. The miners work in
pairs, so that one may assist the other in case of accident, or of