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Who Invented the Telephone?
It's widely recognized that Alexander Graham Bell invented the telephone. Unless you're aware that Elisha Gray, Antonio Meucci, Johann Philipp Reis, Amos Dolbear and others also may have invented it. Thomas Edison was an important contributor to early telephone technologies. Ever since that same day in February 1876 when both Bell and Gray submitted competing patent documents to the U.S. Patent Office, debates have persisted regarding the paternity of the telephone.
The question is not easy to answer. There have been some 600 legal cases (Beauchamp) related to the invention. Bell was the victor in the cases that mattered. Who invented the telephone has as much to do with patents, lawyers, political maneuvering, and intrigue as with inventors. See [Aitken] for a wonderful logical development of the main players and related controversies.
Gray's Caveat
On February 14, 1876, Gray signed and submitted a Caveat document that described a telephone that used a liquid transmitter. A Caveat was similar to a patent application with figures and a detailed description but with no request for an examination. So, in some ways Gray's submission was considered of lesser stature than Bell's full patent application.
Which document arrived first is contentious and has fueled numerous discussions and legal battles over the years, with both sides presenting compelling arguments and evidence in support of their claims. Gray's assertion was not without its supporters, but Bell's patent ultimately secured his place in history.
Fig 1 (upper) is an image from Gray's notebook. It is similar to a drawing in one of Bell's notebooks (lower). Liquid-based transmitters were among several early methods to convert sound waves to electrical signals.
Comparing Gray and Bell's methods
Fig 1, Liquid transmitters from Gray and Bell, 1876 [Hounshell]
The text below is from [Hounshell] and describes Fig 1.
Striking parallels between the telephones envisioned by Elisha Gray and Alexander Graham Bell are evident in their respective sketches of the instruments. Both Gray's transmitter (top) and Bell's (bottom) depended on varying the resistance to the flow of current from a battery.
Both variations would be caused by the vertical movement of a needle in a liquid (electrolyte) bath; the motion would be due to the response of a diaphragm to the sound waves of the human voice. In Gray's transmitter the variation in resistance would depend on changes in the distance between the tip of the needle and the bottom electrode.
In Bell's the variation would depend on the changes in the area of the wedge-shaped needle tip immersed in the bath. The varying current would then pass through an electromagnet (right) at the receiving end of the circuit; variations in the magnetic field would cause a second diaphragm (in Gray's scheme) or a metal reed (in Bell's) to vibrate, thereby reproducing the sound waves that actuated the transmitter.
Gray made the sketch of his device on February 11, 1876, some two months after he conceived the idea. Bell made his sketch on March 9, 24 days after filing his patent application.
Fig 2, portrait of Elisha Gray (NIHF)
For more on the telephone see the article on transmitters.
Quick advancements
Naturally, there is much more to the story. The first two years from 1876-1878 produced exponential advancements in the quality of transmitted and received speech. Bell and Watson quickly moved from liquid transmitters to using electromagnetic or carbon granule types. Both the transmitter and receiver were difficult to perfect for practical commercialization.
Bell's first fully developed telephone used a horseshoe magnet, seen in Fig 3. The magnet is "in series" with 2 coils (seen with the wires). Together with the metal diaphragm, the coils and magnet form the basics of the telephone. See [Meyer] for more on the details of this telephone
Fig 3, Bell's first practical telephone, 1876. Smithsonian Museum USA
This device served as both a transmitter and a receiver. From Bell's patent US186,787 he states: The operation and use of this instrument are as follows: I would premise by saying that this instrument is and may be used both as a transmitter and as a receiver. That is to say, the sender of the message will use an instrument in every particular identical in construction and operation with that employed by the receiver, so that the same instrument can be used.
It did not take long before a much improved version was invented by Bell and Watson. Fig 4 [Meyer] shows a set with separate transmitter and receiver. The ringer bell was invented by Thomas Watson.
Fig 4, Typical telephone set from 1877-1878 (AT&T Archive and History Center)
It's impressive how quickly the Fig 4 telephone was developed, just 18-24 months after the Fig 3 version. The Fig 4 telephone was likely built by a Bell contractor. In 1881 Bell purchased a factory from Charles Williams where the first several thousand telephones were made [Fred De Land]. He also bought an interest in the Western Electric Manufacturing Company of Chicago and merged the two into one organization, which became the Western Electric Company.
Others including Blake and Edison greatly improved (1878-9) on Bell's first transmitter. [Fred De Land] said, "It is a fact that no modern transmitter exceeds the Blake in clearly and distinctly reproducing the articulation of the subscriber."
Experts in early telephony continue to argue about the paternity of the telephone. But no one can deny that Bell and Watson made the first practical and reliable telephones that shaped the future of communications.
References
Aitken, William, Who Invented the Telephone, 1939
Beauchamp, Christopher, Invented by Law: Alexander Graham Bell and the Patent That Changed America, 2015.
Fred De Land, Popular Science Monthly, May 1907, Notes on the Development of Telephone Service VI.
Hounshell, David, Two Paths to the Telephone, Scientific American, Vol. 244, January 1981
Meyer, Ralph, Bell, Watson, Soft Iron, and the Insight That Commercialized the Magneto Telephone, PROCEEDINGS OF THE IEEE, Vol. 108, No. 12, December 2020 .
Meszar, J., The New Splendor of Switching, Bell Laboratories Record, Nov 1953
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