Telephone,
the device, that played a vital role in turning the world in a 'global village' is not
just an instrument, but a revolution in itself. The invention of telephone makes an
interesting reading. It enables people to talk to each other over great
distances by means of electricity. It was mankind’s dream realized by Alexander
Graham Bell.
It was Robert Hooke who
first suggested the model of string telephone in 1667. Two persons connected by a light
piece of string having a tin at each end, and were able to send verbal messages over it.
However, it was not a very practical device and didn’t work over long distances. The
device, suggested by Robert Hooke, was working on this principle – When you speak,
the vocal chords in your throat vibrate. This causes tiny changes in the air pressure, and
sound waves radiate from your mouth. When you listen to someone, the sound waves coming
from the person’s mouth enter your ear. The small pressure changes are converted into
nerve signals, which are sent to your brain. But air does not transmit sound waves very
well over a distance. So some other alternative was needed.
In order to find out such
alternative, two Americans working independently of each other, invented telephones at the
same time. We know Alexander Graham Bell as the inventor of the telephone because he got
to the Patent Office a few hours before Elisha Gray, the other inventor, on February 14,
1876.
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Bell brought together the work of several scientists to invent the telephone. His telephone was based on electromagnets. He used two of them joined together by two wires. This worked, but not efficiently. However, it was the discovery of the carbon microphone that ensured the early success of the telephone. Bell’s telephone was working on this principle - When you speak into the microphone of the telephone, the sound waves from your mouth make the diaphragm vibrate. The diaphragm presses on to carbon granules and this affects the electric current that flows through them. The microphone converts the sound waves into the electric current. This electric current is fed down a pair of wires to the receiving telephone. Here, the fluctuating current passes through the coil of wire and makes the diaphragm vibrate. This reproduces the sound waves, which entered the microphone. Thus, enabling the messenger and the recipient to communicate through this device. |
 The first
telephone systems had no telephone exchange. Like some small internal office telephone
systems today, wires to every other telephone connected each telephone in the system. For
example, in a network of 50 telephones, each one had to have 49 pairs of wires connected
to it, each with a switch. A much simpler arrangement was to link each telephone by a
single pair of wires to a central exchange where all the switching took place. In most
early telephone exchanges, operators made the connections by plugging wires into numbered
sockets in a switchboard.
Bell promoted his telephone very
enthusiastically. He demonstrated his wonderful device all over America and also in
England. Due to Bell’s efforts, the development of the telephone was rapid in
America. However, in those days, in the countries like England and France, people were not
so enthusiastic about the telephone. They preferred usage of messenger boys. One of the
reasons being sound quality of the early telephone being poor and it failed working over
long distances. Another factor was that it was very expensive. In 1878, the cost of
connecting two offices with telephones was more than a year’s wages for a servant. At
that time, a lot of money had been invested in the Telegraph system. So the investors did
not want to encourage something, which would affect their business. Since the telephone
was to carry speech, it had to be of a higher quality than telegraph lines. Telephones had
to be connected by pairs of copper wires. These wires were carried overhead from pole to
pole. But there was a possible danger of natural factors like gales, thunderstorm and
freezing of wires due to snow. The best solution was underground wiring (cabling), but it
was very expensive. This problem was solved gradually with the development of modern
communication technology.
Another limitation of the
system was that the telephone just linked two houses or offices, together. There was no
alternative of connecting one pair of telephones to the other pair. Obviously, this was
inconvenient. So very quickly, exchanges were built and installed to enable this to
happen. The first exchanges were called Manual Exchanges that were operated by the people
called Operators. The first Automatic Exchange was patented in 1891, following Manual
Exchanges. It was called ‘Strowger Exchange’ and was named after its inventor
Almon B. Strowger.
Today, there are over two hundred million
telephones in use throughout the world. Anybody can talk to anyone, whether he is in the
next street, the next city, next country or half–way round the globe. In some cases,
a user may have to ask a telephone operator in his local telephone exchange to connect the
call for him. But more and more calls can now be connected automatically. The caller
signaling the telephone number he wants to get in touch through his telephone dialed is
the required telephone number. Some of the latest telephones called videophones have a
small display screen so that the callers can see each other as they talk. Now a days, the
advanced technology Cellular Telephones have transformed the living standards of the
world. |
