undeveloped; but
not in the United States. Here in one year it had become famous, and
in three years it had become rich. Bell's invincible patent was soon
buttressed by hundreds of others. An open-door policy was adopted for
invention. Change followed change to such a degree that the experts of
1880 would be lost to-day in the mazes of a telephone exchange.

The art of the telephone engineer has in thirty years grown from the
most crude and clumsy of experiments into an exact and comprehensive
profession. As Carty has aptly said, "At first we invariably approached
every problem from the wrong end. If we had been told to load a herd of
cattle on a steamer, our method would have been to hire a Hagenbeck to
train the cattle for a couple of years, so that they would know enough
to walk aboard of the ship when he gave the signal; but to-day, if we
had to ship cattle, we would know enough to make a greased chute and
slide them on board in a jiffy."

The telephone world has now its own standards and ideals. It has a
language of its own, a telephonese that is quite unintelligible to
outsiders. It has as many separate branches of study as medicine or law.
There are few men, half a dozen at most, who can now be said to have
a general knowledge of telephony. And no matter how wise a telephone
expert may be, he can never reach perfection, because of the amazing
variety of things that touch or concern his profession.

"No one man knows all the details now," said Theodore Vail. "Several
days ago I was walking through a telephone exchange and I saw something
new. I asked Mr. Carty to explain it. He is our chief engineer; but
he did not understand it. We called the manager. He did n't know, and
called his assistant. He did n't know, and called the local engineer,
who was able to tell us what it was."

To sum up this development of the art of tele-phony--to present a
bird's-eye view--it may be divided into four periods:

1. Experiment. 1876 to 1886. This was the period of invention, in which
there were no experts and no authorities. Telephonic apparatus consisted
of makeshifts and adaptations. It was the period of iron wire, imperfect
transmitters, grounded circuits, boy operators, peg switchboards, local
batteries, and overhead lines.

2. Development. 1886 to 1896. In this period amateurs became engineers.
The proper type of apparatus was discovered, and was improved to a
high point of efficiency. In this period came the multipl