heir best in the
struggle against the difficulty; and yet the water has beaten them.
Rich as are the lodes which lie beneath the water, the mining engineer
is compelled to confess that the metal value which they contain would
not leave, after extraction, a sufficient margin to pay for the
enormous cost of draining the shafts. In some instances, indeed, it
remains exceedingly doubtful whether pumps of the largest capacity
ever attained in any part of the world would cope with the task
entailed in draining the abandoned shafts. The underground workings
have practically tapped subterranean rivers which, to all intents and
purposes, are inexhaustible. Or it may be that the mine has penetrated
into some hollow basin of impermeable strata filled only with porous
material which is kept constantly saturated. To drain such a piece of
country would mean practically the emptying of a lake.

Subaqueous mining is therefore one of the big problems which the
mining engineer of the twentieth century must tackle. To a certain
extent he will receive guidance in his difficult task from the
experiences of those who have virtually undertaken submarine mining
when in search of treasure lost in sunken ships. The two methods of
pumping and of subaqueous mining will in some places be carried out
conjointly.

In such instances the work assigned to the pumping machinery will be
to keep free of water those drives in which good bodies of ore were
exposed when last profitable work was being carried on. All below that
level will be permitted to fill with water, and the work of boring by
means of compressed air, of blasting out the rock and of filling the
trucks, will all be performed under the surface. For the shallower
depths large tanks, open at the top, will be constructed and slung
upon trucks run on rails along the lowest drives. Practically this
arrangement means that an iron shaft, closed at the sides and bottom,
and movable on rails laid above the surface, will be employed to keep
the water out. Somewhat similar appliances have been found very
useful in the operations for laying the foundations of bridges.

The details requiring to be worked out for the successful working of
subaqueous systems of mining are numerous and important. Chief among
these must be the needful provision for enabling the miner to see
through strong glass windows near the bottom of the iron shaft, by the
aid of electric lights slung in the water outside, and thus to