made with several stages, in which either the tubs
or waggons can be placed, or where the miners can stand or sit. If a
rope breaks, a spring placed above the cage and kept taut by the tension
of the rope, is set free, and acts upon a double clutch made of the best
tempered steel. This catch or wedge falls between the wooden guide and
a part of the cage, and brings the latter immediately to a stand-still.
By this means numberless accidents have been prevented. The man-engines
which have been described are dangerous for novices, for should a person
stop at the wrong time, he may be hurled to the bottom, or crushed at
the return stroke.

One of the most frequent accidents to which miners are exposed arises
from an outbreak of fire-damp. To avoid this, various safety-lamps have
been invented. The most celebrated is that known as Sir Humphrey Davy's
lamp. The flame is enclosed in a fine wire gauze, through which, under
ordinary circumstances, the gas cannot penetrate. There are other lamps
in use constructed on the same principle, but superior in some respects.
Too often, however, the miners open them at some fatal moment, or enter
the mine, against orders, with naked candles. Still, by means of these
lamps, when properly employed, many accidents have been prevented.
Another invention exists by which a person can enter in the midst of
impure air. The apparatus was devised by Monsieur Kouquayrol, a French
engineer. It consists of a reservoir made of sheet iron, into which the
air is forced, and, by an ingeniously contrived pump, is secured like a
knapsack to a man's back, and the air is conveyed by means of a tube to
the mouth of a nose, and thus into the lungs at the ordinary pressure,
while a small external valve allows of the escape of the air after it
has been respired.

A still more simple apparatus has been invented by Monsieur Galibert.
The system for condensing the pure air is more perfect, while the
reservoir consists of a well-prepared goat-skin, which, when inflated, a
man can with ease carry on his back. It is furnished with a similar
contrivance to the former, a tube passing from the reservoir to the
mouth, while the nostrils are compressed, the eyes and head are
protected, so that provided with it, a person may exist for a quarter of
an hour in the foulest atmosphere, or in the midst of dense smoke.
Although the metal miner is subjected to fewer accidents than are his
brethren working in coal mines,