In 1873, Alexander Graham Bell, a professor of vocal physiology, obtained financial backing for an invention that he was working on from Gardiner Greene Hubbard, a lawyer, and George Sanders, a businessman.
The proposed invention was a “harmonic telegraph” which would transmit several morse code messages simultaneously at different frequencies. Bell used some of the money to hire Thomas Watson, a talented young machinist, to assist him.
On 2 June 1875, Bell and Watson were testing a harmonic telegraph when Bell heard the transmitted sound of Watson plucking a tuned string. Bell realised that the device had been adjusted incorrectly allowing a constant current to flow and that this was the key to transmitting sound and speech. Bell and Watson were still unable to make a working telephone but, nevertheless on 14 February 1876, Bell filed a patent.
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Samuel Morse spent 40 years developing the telegraph and morse code because he failed to get a message by mail informing him that his wife was dying in time to see her.
A few hours later Elisha Grey, a professional inventor, also lodged a notice of intent to patent a telephone. In Bell’s application, the key principle of variable resistance was scrawled in the margin as though it was an afterthought. It was speculated that Bell had heard about Grey’s invention and rushed to amend his patent. Many other patent applications and some 600 lawsuits followed Bell’s, most claiming either a prior invention or that the device Bell described would not work.
In any case, within a week of lodging his patent, Bell and Watson produced their first working telephone. In July 1877, Bell, Sanders and Hubbard formed the Bell Telephone Company and decided to lease, rather than sell, telephones. Within the next 17 years, over 1700 other telephone companies had been formed.
In 1878, the first commercial switchboard was installed in New Haven, Conneticut. It served 8 lines and 21 telephones. Prior to this there had to an individual line had to be laid between each pair of telephones that were to communicate.The first automatic telephone switch, allowing subscribers to dial a number themselves, rather than have an operator make the connection, was patented in 1889 in Almon Strowger. This required a new type of telephone with a dialling mechanism. The rotating finger-wheel dial was invented by A.E. Keith, J. Erickson and C.J. Erickson – no relation to Lars Magnis Ericsson, the owner of a small telegraph repair business in Stockholm. In the same year, L.M. Ericsson manufactured its first telephones.
In 1906, Lee de Forest invented the vacuum tube. This made electronic amplification and true long distance telephony possible. The first American transcontinental telephone line, between New York and San Francisco, was opened in 1915. Intercontinental telephone communications began with the first radio telephony link between the United States and Great Britain in 1927. However, because of the intervening Depression and Second World War, it was not until 1956 that the first Transatlantic cable was completed.