Invented by : Alexander Graham Bell
Invented in year : 1876
The Telephone is a telecommunications device that transmits and receives sound, most commonly the human voice. The device operates principally by converting sound waves into electrical signals, and electrical signals into sound waves. Such signals when conveyed through telephone networks and often converted to electronic and/or optical signals - enable nearly every telephone user to communicate with nearly every other worldwide. The telephone operates on simple principles. A telephone mouthpiece contains a thin metallic coating separated from an electrode by a thin barrier (today we use plastic) which connects to a wire carrying an electric current. When a person speaks into the mouthpiece, the acoustic vibrations from her speech push the metallic coating slightly closer to the electrode, resulting in variations in voltage and therefore a speedy conversion from acoustic to electric energy. The electric pulses are conveyed through a wire to the speaker on the other end, where electric pulses are converted into acoustic energy again.
History of the Invention
There are many who were considered to be credited with inventing the telephone include Antonio Meucci, Philip Reis, Elisha Gray and Alexander Graham Bell. But in the 1870s two main contenders were Elisha Gray and Alexander Graham Bell. Both independently designed devices that could transmit speech electrically (the telephone). Both men rushed their respective designs to the patent office within hours of each other, Alexander Graham Bell patented his telephone first. Elisha Gray and Alexander Graham Bell entered into a famous legal battle over the invention of the telephone, which Bell won. The telegraph and telephone are both wire-based electrical systems, and Alexander Graham Bell's success with the telephone came as a direct result of his attempts to improve the telegraph.
When Bell began experimenting with electrical signals, the telegraph had been an established means of communication for some 30 years. Although a highly successful system, the telegraph, with its dot-and-dash Morse code, was basically limited to receiving and sending one message at a time. Bell's extensive knowledge of the nature of sound and his understanding of music enabled him to conjecture the possibility of transmitting multiple messages over the same wire at the same time. Although the idea of a multiple telegraph had been in existence for some time, Bell offered his own musical or harmonic approach as a possible practical solution. His "harmonic telegraph" was based on the principle that several notes could be sent simultaneously along the same wire if the notes or signals differed in pitch.
On June 2, 1875, Alexander Graham Bell while experimenting with his Harmonic Telegraph technique discovered he could hear sound over a wire. The sound was that of a twanging clock spring. Bell's greatest success was achieved on March 10, 1876, when he conducted the first successful telephone transmission of clear speech using a liquid transmitter when Bell spoke into his device, “Mr. Watson, come here, I want to see you.” and Watson heard each word distinctly. And on 30th January, 1877 - Bell is granted U.S. patent 186,787 for an electromagnetic telephone using permanent magnets, iron diaphragms, and a call bell.
Development in the Invention of the Telephone
First Exchange - In 1877, the first telephone system, known as an Exchange, which is a practical means of communicating between many people who have telephones, was installed in Hartford, Connecticut. In 1883 and the first exchange linking two major cities was established between New York and Boston The first exchange outside the United States was built in London in 1879. The exchange involved a group of operators working at a large switchboard. The operators would answer an incoming telephone call and connect it manually to the party being called. The first automatic telephone exchange was patented by Almon Strowger of Kansas City in 1891 and installed in 1892, but manual switchboards remained in common use until the middle of the twentieth century.
Pay Telephone - In 1889, the coin operated pay telephone was patented by William Gray of Hartford .
Rotary Dial Telephone - In 1923, the First Rotary Dial Telephone was developed by Antoine Barnay in France.
Mobile Telephone - In 1924, the mobile telephone was invented by Bell Telephone Company and introduced into New York City police cars . Although the first commercial mobile telephone service became available in St. Louis, Missouri in 1946, the mobile telephone would not become common for another four decades.
Touch-Tone System - In 1941, the First Touch-Tone System was installed in Baltimore, MD. These phones used tones in the voice frequency range rather than pulses generated by rotary dials. Operators in a central switching office pushed the buttons; it was much too expensive for general use. However, the Bell System was intrigued by touch-tone because it increased the speed of dialing.
Picturephone - In 1956, the First Picturephone test system was built Despite improvements, Picturephone was big and expensive, therefore rejected by people.
Cell Phone - In 1978, American Telephone and Telegraph’s (AT&T) Bell Laboratories began testing a mobile telephone system based on hexagonal geographical regions called cells. As the caller’s vehicle passed from one cell to another, an automatic switching system would transfer the telephone call to another cell without interruption. The cellular telephone system began nationwide usage in the United States in 1983.
Role of Telephone in the Improvement Of Human Life
- It facilitated Communication
- It became indispensable part of business, industry and government.
- It also became one of the most common household appliances in the world
