f hundreds of
immense forests. One secret of the unprecedented late growth of cities is
discovered in the steam engine, or the coal which feeds it.

A pound of good coal, used in a good engine, stands for the work of six
horses for an hour; a ton of coal for the work of thirteen hundred horses
for a day of ten hours; ten thousand tons of coal, used in a day by
single lines of railways, stand for the work of thirteen million horses,
working ten hours a day. In 1894 the English mines produced 188,277,525
tons of coal. In Great Britain alone, coal does the work of more than a
hundred millions of men, and adds proportionately to the fabulously
increasing wealth of those fortunate islands.

The Ingrams had solved two important problems, and on their practicable
application depended the success of the great Harris-Ingram experiment.
The more important of the two was the unlocking of the sun's stored
energy, electricity, at the coal mines. The second was a device for
conveying this energy from the mines to the steel plant, and it had been
patented to protect it.

Since electricity possibly travels on the surface of wires or metals, the
Ingrams patented a valuable device of small corrugated copper tubes,
strengthened in the center by steel wires, and thus the carrying capacity
of electricity was greatly increased, and the amount of costly copper
much decreased. These corrugated tubes enclosed in cheap glass, and
surrounded with oil, were laid in properly prepared conduits of vitrified
fire-clay sewer pipes. Without the intervention of the steam engine, by
a surprisingly simple process, electrical force was liberated chemically
at the mines and transferred for multiple uses at the steel plant.
Expensive coal-freights were thus saved. All the slack coal was utilized,
and instead of the waste of nine-tenths of the stored energy of the coal,
only one tenth was now lost. To husband properly the fruits of so great a
discovery, it was decided not to patent this latter invention, which if
disclosed would give too great publicity to the details.

The electrical works at the mines were constructed of safe-steel walls
and roof, and so built that the operations of generating electricity
directly from coal were conducted in secret in several separate
apartments, so that no single operator without the knowledge of all the
initiated employees would be able to successfully work the inventions.
The dozen initiated employees had made life lon