. From the poles the
wires overflowed to the housetops, increasing the difficulty of the
engineers. How to protect the wires so that they could be placed
underground was the problem.

We have noticed that Theodore Vail had been brought to the head of
the Bell system in its infancy and had led the fight against the rival
companies until it was thoroughly established. Now he was directing
his genius and executive ability to so improving the telephone that
it should serve every need of communication. While the engineers
discussed theories Vail began actual tests. A trench five miles long
was dug beside a railway track by the simple expedient of hitching a
plow to a locomotive. In this trench were laid a number of wires, each
with a different covering. The gutta-percha and the rubber coverings
which had been used in cable construction predominated. It was found
that these wires would carry the telephone currents, not as well as
might be desired, but well enough to assure Vail that he was on the
right track. The companies began to place their wires underground, and
Vail saw to it that the experiments with coverings for telephone wires
were continued. The result was the successful underground cables in
use to-day.

At the same time Vail and his engineers were seeking to improve the
wires themselves. Iron and steel wires had been used, but they proved
unsatisfactory, as they rusted and were poor conductors. Copper was
an excellent conductor, but the metal in the pure state is soft and
no one then knew how to make a copper wire that would sustain its own
weight. But Vail kept his men at the problem and the hard-drawn copper
wire was at length evolved. This proved just what was needed for the
telephone circuits. The copper wire was four times as expensive as the
iron, but as it was four times as good Vail adopted it.

John Carty had rather more than kept pace with these improvements. He
was but twenty-six years of age when Union N. Bethell, head of the New
York company, picked Carty to take charge of the telephone engineering
work in the metropolis. Bethell was Vail's chief executive officer,
and under him Carty received an invaluable training in executive work.
Carty's largest task was putting the wires underground, and here again
he was a tremendous success. He found ways to make cables cheaper
and better, and devised means of laying them at half the former cost.
Having solved the most pressing problems in this field, his e