simple process. Vail bought thirty
pounds of it and scattered it in various parts of the United States,
to note the effect upon it of different climates. One length of it may
still be seen at the Vail homestead in Lyndonville, Vermont. Then this
hard-drawn wire was put to a severe test by being strung between Boston
and New York. This line was a brilliant success, and the new wire was
hailed with great delight as the ideal servant of the telephone.

Since then there has been little trouble with copper wire, except
its price. It was four times as good as iron wire, and four times as
expensive. Every mile of it, doubled, weighed two hundred pounds and
cost thirty dollars. On the long lines, where it had to be as thick as
a lead pencil, the expense seemed to be ruinously great. When the first
pair of wires was strung between New York and Chicago, for instance,
it was found to weigh 870,000 pounds--a full load for a twenty-two-car
freight train; and the cost of the bare metal was $130,000. So enormous
has been the use of copper wire since then by the telephone companies,
that fully one-fourth of all the capital invested in the telephone has
gone to the owners of the copper mines.

For several years the brains of the telephone men were focussed upon
this problem--how to reduce the expenditure on copper. One uncanny
device, which would seem to be a mere inventor's fantasy if it had not
already saved the telephone companies four million dollars or more, is
known as the "phantom circuit." It enables three messages to run at the
same time, where only two ran before. A double track of wires is made
to carry three talk-trains running abreast, a feat made possible by the
whimsical disposition of electricity, and which is utterly inconceivable
in railroading. This invention, which is the nearest approach as yet to
multiple telephony, was conceived by Jacobs in England and Carty in the
United States.

But the most copper money has been saved--literally tens of millions of
dollars--by persuading thin wires to work as efficiently as thick ones.
This has been done by making better transmitters, by insulating the
smaller wires with enamel instead of silk, and by placing coils of a
certain nature at intervals upon the wires. The invention of this last
device startled the telephone men like a flash of lightning out of a
blue sky. It came from outside--from the quiet laboratory of a Columbia
professor who had arrived in the United States