Revolutionary Discovery of Telephone by Alexander Graham Bell

Alexander Graham Bell was working on a method of sending multiple tones on a telegraph wire using a multi-reed device. Bell thought it might be possible to generate undulating electrical currents that corresponded to sound waves. Bell also thought that multiple metal reeds tuned to different frequencies like a harp would be able to convert the undulatory currents back into sound. But he had no working model to demonstrate the feasibility of these ideas.

In March 1875, Bell visited the famous scientist Joseph Henry, who was then director of the Smithsonian Institution, and asked Henry's advice on the electrical multi-reed apparatus that Bell hoped would transmit the human voice by telegraph. Henry replied that Bell had "the germ of a great invention". When Bell said that did not have the equipment needed to continue his experiments, nor the ability to create a working model of his ideas, Henry replied, "Get it!"

Bell hired Thomas A. Watson, an experienced electrical designer and mechanic as his assistant and the two of them experimented with acoustic telegraphy. On 2 June 1875, Watson accidentally plucked one of the reeds and Bell, at the receiving end of the wire, heard the overtones of the reed; overtones that would be necessary for transmitting speech. That demonstrated to Bell that only one reed or armature was necessary, not multiple reeds. This led to the "gallows" sound-powered telephone, which was able to transmit indistinct, voice-like sounds, but not clear speech.

In 1875, Bell developed an acoustic telegraph and drew up a patent for it. Three days after his patent was issued, Bell succeeded in getting his telephone to work. Vibration of the diaphragm caused a needle to vibrate in the water which varied the electrical resistance in the circuit. When Bell spoke the famous sentence "Mr Watson — Come here — I want to see you" into the liquid transmitter, Watson, listening at the receiving end in an adjoining room, heard the words clearly.

Continuing his experiments in Brantford, Bell brought a working model of his telephone home. On 3 August 1876, from the telegraph office in Mount Pleasant five miles (eight km) away from Brantford, Alexander sent a tentative telegram indicating he was ready. With curious onlookers packed into the office as witnesses, faint voices were heard replying. The following night, he amazed guests as well as his family when a message was received at the Bell home from Brantford, four miles (six km) distant along an improvised wire strung up along telegraph lines, fences, and laid through a tunnel. This time, guests at the household distinctly heard people in Brantford reading and singing. These experiments clearly proved that the telephone could work over long distances.

Bell and his partners, Hubbard and Sanders, offered to sell the patent outright to Western Union for $100,000. The president of Western Union balked, countering that the telephone was nothing but a toy. Two years later, he told colleagues that if he could get the patent for $25 million he would consider it a bargain. By then, the Bell company no longer wanted to sell the patent. Bell began a series of public demonstrations and lectures in order to introduce the new invention to the scientific community as well as the general public. The enthusiasm surrounding Bell's public displays laid the groundwork for universal acceptance of the revolutionary device.

The Bell Telephone Company was created in 1877, and by 1886, over 1,50,000 people in the U.S. owned telephones. In 1879, the Bell company acquired Edison's patents for the carbon microphone from Western Union. This made the telephone practical for long distances and it was no longer necessary to shout to be heard at the receiving telephone.