Invention of the telephone
The carbon microphone was independently developed around 1878 by David Edward Hughes in England and Emile Berliner and Thomas Edison in the US. Although Edison was awarded the first patent in mid-1877, Hughes had demonstrated his working device in front of many witnesses some years earlier, and most historians credit him with its invention.
Invention of the telephone
After Bell and Watson discovered on June 2, 1875, that movements of the reed alone in a magnetic field could reproduce the frequencies and timbre of spoken sound waves, Bell reasoned by analogy with the mechanical phonautograph that a skin diaphragm would reproduce sounds like the human ear when connected to a steel or iron reed or hinged armature. On July 1, 1875, he instructed Watson to build a receiver consisting of a stretched diaphragm or drum of goldbeater's skin with an armature of magnetized iron attached to its middle, and free to vibrate in front of the pole of an electromagnet in circuit with the line. A second membrane-device was built for use as a transmitter. This was the "gallows" phone. A few days later they were tried together, one at each end of the line, which ran from a room in the inventor's house, located at 5 Exeter Place in Boston, to the cellar underneath. Bell, in the work room, held one instrument in his hands, while Watson in the cellar listened at the other. Bell spoke into his instrument, "Do you understand what I say?" and Watson answered "Yes". However, the voice sounds were not distinct and the armature tended to stick to the electromagnet pole and tear the membrane.