ble swiftness to
the receiving instrument, and these are translated back into the
vibrations that produce speech. This is really what takes place when you
talk over a toy telephone made by a string stretched between the two tin
mouth-pieces held at opposite sides of the room, with the difference
that in the telephone the vibrations are carried electrically, while the
toy carries them mechanically and not nearly so perfectly.

For once the world realised immediately the importance of a
revolutionising invention, and telephone stations soon began to be
established in the large cities. Quicker than the telegraph, for there
was no need of an operator to translate the message, and more accurate,
for if spoken clearly the words could be as clearly understood, the
telephone service spread rapidly. Lines stretched farther and farther
out from the central stations in the cities as improvements were
invented, until the outlying wires of one town reached the outstretched
lines of another, and then communication between town and town was
established. Then two distant cities talked to each other through an
intermediate town, and long-distance telephony was established. To-day
special lines are built to carry long-distance messages from one great
city to another, and these direct lines are used entirely except when
storms break through or the rush of business makes the roundabout route
through intermediate cities necessary.

As the nerves reaching from your finger-tips, from your ears, your eyes,
and every portion of your body come to a focus in your brain and carry
information to it about the things you taste, see, hear, feel, and
smell, so the wires of a telephone system come together at the central
station. And as it is necessary for your right hand to communicate with
your left through your brain, so it is necessary for one telephone
subscriber to connect through the central station with another
subscriber.

The telephone has become a necessity of modern life, so that if through
some means all the systems were destroyed business would be, for a time
at least, paralysed. It is the perfection of the devices for connecting
one subscriber with another, and for despatching the vast number of
messages and calls at "central," that make modern telephony possible.

To handle the great number of spoken messages that are sent over the
telephone wires of a great city it is necessary to divide the territory
into districts, which vary in s