In 1876, Alexander Graham Bell (1847-1922) was working on devices to help the hearing-impaired. Bell then developed a simple combination receiver and transmitter using a bar magnet, a coil of fine wire and a thin metal disk. Bell's device worked both as a microphone and an earphone. Its urgent use was demonstrated by Bell when he spilled some acid on his trousers, and exclaimed, summoning his Laboratory assistant in the next room -- 'Come here. Watson. I need you!' Unfortunately, the sound was quite weak and could not serve as the basis of a commercial telephone. However, the receiver portion of his device worked very well and since has been used in virtually all commercial telephones around the world.
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.
David Edward Hughes invented the carbon microphone, which was essential to the development of the telephone.
The missing element was a better transmitter or microphone. A device that would generate a strong electrical equivalent of the voice would complete a telephone that could be used for long distance communication. This device, the carbon microphone, was invented by both Edison and Francis Blake in 1877 and patented by Edison. It is still in use in many phones today. A battery provided the necessary electrical power and two copper wires strung on telephone poles connected the interested parties. Additional people could tap into these wires with their own phone units, and thus all be able to talk to one another - even at the same time. Perhaps this presaged the current Internet.
For a number of years, telephones operated without the use of amplifiers to step up the power going out on...