Quick facts
turn: The first two-way telephone call over external lines
date: October 9, 1876
where: Cambridgeport to Boston, Massachusetts
from: Alexander Graham Bell and Thomas Watson
On the afternoon of October 9, 1876, Alexander Graham Bell was in Boston when he had an accident Three hour conversation With his assistant and fellow inventor Thomas Watson. The matter would not have been noteworthy, had Watson not been located across the Charles River, at Cambridgeport.
Bell and Watson spoke over their devices early in March of that year, shortly after Bell’s improved “telegraph” device was patented. but Cracked order “Mr. Watson, come here; I want to see you,” it sounded only a short distance away.
In contrast, the call on that October day lasted a few hours and was broadcast Over long telegraph wires.
Bell was in the middle of a crowded field of inventors who were dreaming up new ways to transmit sound via electricity. A few decades ago, Antonio Meucci created… Take preliminary steps to obtain a patent – “Telephone” to communicate with his wife, who is bedridden in another room. In 1861, German inventor Johann Philipp Reiss coined the term “telephone” to describe his device, which converted sound waves into an electrical signal and back. His transfers Faithfully reproduced melodiesBut the words were too distorted to be understood. At about the same time as Bell, Elisha Gray developed a similar design based on a water microphone.
Key to Bell’s ability to transmit sound was the idea of transmitting multiple frequencies simultaneously, which he did using what he called “undulating”—or variable—current rather than the intermittent pulses of current that Samuel Morse used in his telegraph.
Bell’s patent states that “the rate of oscillation of the electric current corresponds to the rate of vibration of the stimulated body, that is, to the pitch of the sound produced.” “The intensity of the current varies with the amplitude of the vibration, that is, with the loudness of the sound.” In short, current encryption features are audio features.
Bell’s prototype used a diaphragm, an inductor (an iron core surrounded by a coil of wire), a permanent magnet, and conducting wires. When a sound wave strikes the diaphragm, pressure waves cause the diaphragm to vibrate. These vibrations moved the inductor, changing the magnetic field it produced, which in turn caused current to flow in the coiled wire. This current is then transmitted through wires to the receiver, which contains the same elements in the opposite direction.
That first long-distance conversation was interesting, but the first telephone line, which was laid in April 1877, was only connected The merchant’s shop with his house. Telephone lines were initially rented in pairs and used to connect separate locations. But the opening “Central exchangesAbout a year later switchboards enabled calls to be routed between sites, greatly improving the utility of the invention.
It would be decades before the first intercontinental and intercontinental calls were made, and the first undersea calls were made Transatlantic telephone cables Developed in 1956.
The telephone industry helped stimulate a number of other modern innovations, including… Keys, The transistor that would usher in the age of computing, Fiber optic cables for data transmissionand Communications satellites.