Telecommunication
The conventional telephone was invented independently by Alexander Bell and Elisha Gray in 1876. Antonio Meucci invented the first device that allowed the electrical transmission of voice over a line in 1849. However Meucci's device was of little practical value because it relied upon the electrophonic effect and thus required users to place the receiver in their mouth to "hear" what was being said. The first commercial telephone services were set-up in 1878 and 1879 on both sides of the Atlantic in the cities of New Haven and London.
Invention of the telephone
Bell exhibited a working telephone at the Centennial Exhibition in Philadelphia in June 1876, where it attracted the attention of Brazilian emperor Pedro II plus the physicist and engineer Sir William Thomson (who would later be ennobled as the 1st Baron Kelvin). In August 1876 at a meeting of the British Association for the Advancement of Science, Thomson revealed the telephone to the European public. In describing his visit to the Philadelphia Exhibition, Thomson said, "I heard [through the telephone] passages taken at random from the New York newspapers: 'S.S. Cox Has Arrived' (I failed to make out the S.S. Cox); 'The City of New York', 'Senator Morton', 'The Senate Has Resolved To Print A Thousand Extra Copies', 'The Americans In London Have Resolved To Celebrate The Coming Fourth Of July!' All this my own ears heard spoken to me with unmistakable distinctness by the then circular disc armature of just such another little electro-magnet as this I hold in my hand."