Telephone and Multiple Telegraph
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.
By October 1874, Bell's research had progressed to the extent that he could inform his future father-in-law, Boston attorney Gardiner Greene Hubbard, about the possibility of a multiple telegraph. Hubbard, who resented the absolute control then exerted by the Western Union Telegraph Company, instantly saw the potential for breaking such a monopoly and gave Bell the financial backing he needed. Bell proceeded with his work on the multiple telegraph, but he did not tell Hubbard that he and Thomas Watson, a young electrician whose services he had enlisted, were also exploring an idea that had occurred to him that summer - that of developing a device that would transmit speech electrically. Original drawing of the telephone
While Bell and Watson worked on the harmonic telegraph at the insistent urging of Hubbard and other backers, Bell nonetheless met in March 1875 with Joseph Henry, the respected director of the Smithsonian Institution, who listened to Bell's ideas for a telephone and offered encouraging words. Spurred on by Henry's positive opinion, Bell and Watson continued their work. By June 1875 the goal of creating a device that would transmit speech electrically was about to be realized. They had proven that different tones would vary the strength of an electric current in a wire. To achieve success they therefore needed only to build a working transmitter with a membrane capable of varying electronic currents and a receiver that would reproduce these variations in audible frequencies.
Bell's great success, achieved on March 10, 1876, marked not only the birth of the telephone but the death of the multiple telegraph as well. The communications potential contained in his demonstration of being able to "talk with electricity" far outweighed anything that simply increasing the capability of a dot-and-dash system could imply.
A telephone, also called phone is a communicationtool. Originally it was an electric tool transmitting analoguespeech along wires. Now it is an electronic tool sending digital signals on wires or radio transmission. Using a telephone, twopeople who are in different places can talk to each other. Early telephones needed to be connected with wires which are called fixed or landline telephones. Now telephone calls can be sent with radio. This is called wireless or cordless.
History[change | change source]
Alexander Graham Bell was the first person to patent the telephone, in 1876. Early telephones were wired directly to each other and could only talk to the phone that they were connected to. Later, telephone exchanges allowed connecting to other telephones. During the 20th century the machines that made the connections were automated.
Types of telephones[change | change source]
There are many different types of telephone. A telephone that can be carried around is called a mobile phone or cell phone. These became popular in the late 1980s. It has become common for people carry mobile phones and in some places it is unusual to not have one. The majority are smartphones, which can be used as computers. Some mobile phones are able to make telephone calls using communications satellites instead of masts on the ground, which means people can make calls from anywhere in the world.
In most countries there are public payphones. To use one, people pay with coins, a credit card or a prepaid card.
Computers can use a machine called a modem or a Digital subscriber line router to talk to other computers over a telephone line. This allows a computer to connect to other computer networks including the Internet.
Most countries have a telephone network. The telephones in one place are connected to a telephone exchange, and the exchanges are connected together. In less developed countries cell phones are used as a cheaper and faster way to bring modern communications to the countryside.
Telephone number[change | change source]
Most telephones have their own number. Today, telephone numbers are about seven to ten digits long. In many countries, part of the telephone number is called the area code. Area codes are used to make sure the numbers are not the same in two different places. Areas have their own area code, and countries have their own country code.
Usage[change | change source]
By the end of 2009, there were a total of nearly 6 billion mobile and fixed-line telephone subscribers worldwide. This included 1.26 billion fixed-line subscribers and 4.6 billion mobile subscribers.
References[change | change source]
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