Elisha Gray

Elisha Gray (August 2, 1835 – January 21, 1901) was an American electrical engineer who co-founded the Western Electric Manufacturing Company. Gray is best known for his development of a telephone prototype in 1876 in Highland Park, Illinois. Some recent authors have argued that Gray should be considered the true inventor of the telephone because Alexander Graham Bell allegedly stole the idea of the liquid transmitter from him,[1] although Gray had been using liquid transmitters in his telephone experiments for more than two years previously. Bell's telephone patent was upheld in numerous court decisions.

Gray is also considered to be the father of the modern music synthesizer,[2] and was granted over 70 patents for his inventions.[3] He was one of the founders of Graybar, purchasing a controlling interest in the company shortly after its inception.

Elisha Gray
Portrait elisha gray
BornAugust 2, 1835
DiedJanuary 21, 1901 (aged 65)
OccupationEngineer/Inventor
AwardsElliott Cresson Medal (1897)

Biography and early inventions

Born into a Quaker family in Barnesville, Ohio, Gray was brought up on a farm. He spent several years at Oberlin College where he experimented with electrical devices. Although Gray did not graduate, he taught electricity and science there and built laboratory equipment for its science departments.

In 1862 while at Oberlin, Gray met and married Delia Minerva Shepard.

In 1865 Gray invented a self-adjusting telegraph relay that automatically adapted to varying insulation of the telegraph line. In 1867 Gray received a patent for the invention, the first of more than seventy.

In 1869, Elisha Gray and his partner Enos M. Barton founded Gray & Barton Co. in Cleveland, Ohio to supply telegraph equipment to the giant Western Union Telegraph Company. The electrical distribution business was later spun off and organized into a separate company, Graybar Electric Company, Inc. Barton was employed by Western Union to examine and test new products.

In 1870 financing for Gray & Barton Co. was arranged by General Anson Stager, a superintendent of the Western Union Telegraph Company. Stager became an active partner in Gray & Barton Co. and remained on the board of directors. The company moved to Chicago near Highland Park. Gray later gave up his administrative position as chief engineer to focus on inventions that could benefit the telegraph industry. Gray's inventions and patent costs were financed by a dentist, Dr. Samuel S. White of Philadelphia, who had made a fortune producing porcelain teeth. White wanted Gray to focus on the acoustic telegraph which promised huge profits instead of what appeared to be unpromising competing inventions such as the telephone, White made the decision in 1876 to redirect Gray's interest in the telephone.

In 1870, Gray developed a needle annunciator for hotels and another for elevators. He also developed a microphone printer which had a typewriter keyboard and printed messages on paper tape.

In 1872 Western Union, then financed by the Vanderbilts and J. P. Morgan, bought one-third of Gray and Barton Co. and changed the name to Western Electric Manufacturing Company of Chicago. Gray continued to invent for Western Electric.

In 1874, Gray retired to do independent research and development. Gray applied for a patent on a harmonic telegraph which consisted of multi-tone transmitters, that controlled each tone with a separate telegraph key. Gray gave several private demonstrations of this invention in New York and Washington, D.C. in May and June 1874.

Gray was a charter member of the Presbyterian Church in Highland Park, Illinois. At the church, on December 29, 1874, Gray gave the first public demonstration of his invention for transmitting musical tones and transmitted "familiar melodies through telegraph wire" according to a newspaper announcement. This was one of the earliest electric musical instruments using vibrating electromagnetic circuits that were single-note oscillators operated by a two-octave piano keyboard. The "Musical Telegraph" used steel reeds whose oscillations were created by electromagnets and transmitted over a telegraph wire. Gray also built a simple loudspeaker in later models consisting of a vibrating diaphragm in a magnetic field to make the oscillator tones audible and louder at the receiving end. In 1900 Gray worked on an underwater signaling device. After his death in 1901 officials gave the invention to Oberlin College. A few years later he was recognized as the inventor of the underwater signaling device.

On July 27, 1875, Gray was granted U.S. Patent 166,095 for "Electric Telegraph for Transmitting Musical Tones" (acoustic telegraphy).

Telephone

Because of Samuel White's[4] opposition to Gray working on the telephone, Gray did not tell anybody about his invention for transmitting voice sounds until February 11, 1876 (Friday). Gray requested that his patent lawyer William D. Baldwin prepare a "caveat" for filing at the US Patent Office. A caveat was like a provisional patent application with drawings and description but without a request for examination.

Bell-gray-smoking-gun
Excerpts from Elisha Gray's patent caveat of February 14 and Alexander Graham Bell's lab notebook entry of March 9, demonstrating their similarity.

On Monday morning February 14, 1876, Gray signed and had notarized the caveat that described a telephone that used a liquid transmitter. Baldwin then submitted the caveat to the US Patent Office. That same morning a lawyer for Alexander Graham Bell submitted Bell's patent application. Which application arrived first is hotly disputed, although Gray believed that his caveat arrived a few hours before Bell's application.[5] Bell's lawyers in Washington, DC, had been waiting with Bell's patent application for months, under instructions not to file it in the USA until it had been filed in Britain first. (At the time, Britain would only issue patents on discoveries not previously patented elsewhere.)

According to Evenson, during the weekend of February 12–14, 1876, before either caveat or application had been filed in the patent office, Bell's lawyer learned about the liquid transmitter idea in Gray's caveat that would be filed early Monday morning February 14.[5] Bell's lawyer then added seven sentences describing the liquid transmitter and a variable resistance claim to Bell's draft application. After the lawyer's clerk recopied the draft as a finished patent application, Bell's lawyer hand-delivered the finished application to the patent office just before noon Monday, a few hours after Gray's caveat was delivered by Gray's lawyer. Bell's lawyer requested that Bell's application be immediately recorded and hand-delivered to the examiner on Monday so that later Bell could claim it had arrived first. Bell was in Boston at this time and was not aware that his application had been filed.[6]

Five days later, on February 19, Zenas Fisk Wilber, the patent examiner for both Bell's application and Gray's caveat, noticed that Bell's application claimed the same variable resistance feature described in Gray's caveat. Wilber suspended Bell's application for 90 days to give Gray time to submit a competing patent application. The suspension also gave Bell time to amend his claims to avoid an interference with an earlier patent application of Gray's that mentioned changing the intensity of the electric current without breaking the circuit, which seemed to the examiner to be an "undulatory current" that Bell was claiming. Such an interference would delay Bell's application until Bell submitted proof, under the first to invent rules, that Bell had invented that feature before Gray.[7]

Bell's lawyer telegraphed Bell, who was still in Boston, to come to Washington, DC. When Bell arrived on February 26, Bell visited his lawyers and then visited examiner Wilber who told Bell that Gray's caveat showed a liquid transmitter and asked Bell for proof that the liquid transmitter idea (described in Bell's patent application as using mercury as the liquid) was invented by Bell. Bell pointed to an application of Bell's filed a year earlier where mercury was used in a circuit breaker. The examiner accepted this argument, although mercury would not have worked in a telephone transmitter. On February 29, Bell's lawyer submitted an amendment to Bell's claims that distinguished them from Gray's caveat and Gray's earlier application.[8][9] On March 3, Wilber approved Bell's application and on March 7, 1876, U.S. Patent 174,465 was published by the U.S. Patent Office.

Bell returned to Boston and resumed work on March 9, drawing a diagram in his lab notebook of a water transmitter being used face down, very similar to that shown in Gray's caveat.[10] Bell and Watson built and tested a liquid transmitter design on March 10 and successfully transmitted clear speech saying "Mr. Watson – come here – I want to see you." Bell's notebooks became public when they were donated to the Library of Congress in 1976.[11]

Although Bell has been accused of stealing the telephone from Gray[12] because his liquid transmitter design resembled Gray's, documents in the Library of Congress indicate that Bell had been using liquid transmitters extensively for three years in his multiple telegraph and other experiments. In April, 1875, ten months before the alleged theft of Gray's design, the U.S. Patent Office granted U.S. Patent 161,739 to Bell for a primitive fax machine, which he called the "autograph telegraph." The patent drawing includes liquid transmitters.

After March 1876, Bell and Watson focused on improving the electromagnetic telephone and never used Gray's liquid transmitter in public demonstrations or commercial use.[13] When Bell demonstrated his telephone at the Centennial Exhibition in June 1876, he used his improved electromagnetic transmitter, not Gray's water transmitter.

Although Gray had abandoned his caveat, Gray applied for a patent for the same invention in late 1877. This put him in a second interference with Bell's patents. The Patent Office determined, "while Gray was undoubtedly the first to conceive of and disclose the [variable resistance] invention, as in his caveat of February 14, 1876, his failure to take any action amounting to completion until others had demonstrated the utility of the invention deprives him of the right to have it considered."[14] Gray challenged Bell's patent anyway, and after two years of litigation, Bell was awarded rights to the invention, and as a result, Bell is credited as the inventor.

In 1886, Wilber stated in an affidavit[15] that he was an alcoholic and deeply in debt to Bell's lawyer Marcellus Bailey with whom Wilber had served in the Civil War. Wilber stated that, contrary to Patent Office rules, he showed Bailey the caveat Gray had filed. He also stated that he showed the caveat to Bell and Bell gave him $100. Bell testified that they only discussed the patent in general terms, although in a letter to Gray, Bell admitted that he learned some of the technical details. Wilbur's affidavit contradicted his earlier testimony, and historians have pointed out that his last affidavit was drafted for him by the attorneys for the Pan-Electric Company which was attempting to steal the Bell patents and was later discovered to have bribed the U.S. Attorney General Augustus Garland and several Congressmen.

Bell's patent was disputed in 1888 by attorney Lysander Hill who accused Wilber of allowing Bell or his lawyer Pollok to add a handwritten margin note of seven sentences to Bell's application that describe an alternate design similar to Gray's liquid microphone design.[16] However, the marginal note was added only to Bell's earlier draft, not to his patent application that shows the seven sentences already present in a paragraph. Bell testified that he added those seven sentences in the margin of an earlier draft of his application "almost at the last moment before sending it off to Washington" to his lawyers. Bell or his lawyer could not have added the seven sentences to the application after it was filed in the Patent Office, because then the application would not have been suspended.[17]

Gray's further inventions

In 1887 Gray invented the telautograph, a device that could remotely transmit handwriting through telegraph systems. Gray was granted several patents for these pioneer fax machines, and the Gray National Telautograph Company was chartered in 1888 and continued in business as The Telautograph Corporation for many years; after a series of mergers it was finally absorbed by Xerox in the 1990s. Gray's telautograph machines were used by banks for signing documents at a distance and by the military for sending written commands during gun tests when the deafening noise from the guns made spoken orders on the telephone impractical. The machines were also used at train stations for schedule changes.

Gray displayed his telautograph invention in 1893 at the 1893 Columbian Exposition and sold his share in the telautograph shortly after that. Gray was also chairman of the International Congress of Electricians at the World's Columbian Exposition of 1893.

Gray conceived of a primitive closed-circuit television system that he called the "telephote". Pictures would be focused on an array of selenium cells and signals from the selenium cells would be transmitted to a distant station on separate wires. At the receiving end each wire would open or close a shutter to recreate the image.

In 1899 Gray moved to Boston where he continued inventing. One of his projects was to develop an underwater signaling device to transmit messages to ships. One such signaling device was tested on December 31, 1900. Three weeks later, on January 21, 1901, Gray died from a heart attack in Newtonville, Massachusetts.

Some modern authors[18][19] incorrectly[20] attribute the Gray code to Elisha Gray, whereas this code was actually named after Frank Gray, who, however, did not invent the code either.

Gray's publications

Gray wrote several books including:

  • Experimental Researches in Electro-Harmonic Telegraphy and Telephony, 1867–1876 (Appleton, 1878)
  • Telegraphy and Telephony (1878)
  • Electricity and Magnetism (1900) and
  • Nature's Miracles (1900) a nontechnical discussion of science and technology for the general public.

See also

References

Notes

  1. ^ Shulman 2008.
  2. ^ "What is a Synthesizer and how does it work? |". Playpiano.com. Retrieved 2013-09-02.
  3. ^ "Elisha Gray". Oberlin.edu. Retrieved 2013-09-02.
  4. ^ Dr. Samuel S. White of Philadelphia was a wealthy dentist who paid the legal costs and shared in any profits from Elisha Gray's inventions.
  5. ^ a b Evenson 2000, pp. 68–69.
  6. ^ Shulman 2008, pp. 71.
  7. ^ Evenson 2000, pp. 80–81.
  8. ^ Evenson 2000, pp. 81–82.
  9. ^ Baker 2000, pp. A43–A44.
  10. ^ Shulman 2008, pp. 36-37.
  11. ^ "Alexander Graham Bell family papers". LOC.gov. Library of Congress. Archived from the original on 2013-02-16.
  12. ^ Shulman 2008, p. 211.
  13. ^ Evenson 2000, p. 100.
  14. ^ Baker 2000, pp. 90–91.
  15. ^ Evenson 2000, pp. 167–171.
  16. ^ Evenson 2000, pp. 92, 180.
  17. ^ Evenson 2000, pp. 73–74.
  18. ^ Cattermole, Kenneth W. (1969). Principles of Pulse Code Modulation. New York, USA: American Elsevier. ISBN 0-444-19747-8.
  19. ^ Edwards, Anthony William Fairbank (2004). Cogwheels of the Mind: The Story of Venn Diagrams. Baltimore, Maryland, USA: Johns Hopkins University Press. pp. 48, 50. ISBN 0-8018-7434-3.
  20. ^ Knuth, Donald Ervin (2004-10-15). "Generating all n-tuples". The Art of Computer Programming, Volume 4A: Enumeration and Backtracking. pre-fascicle 2a.

Bibliography

  • Shulman, Seth (2008). The Telephone Gambit. New York, New York: W. W. Norton. ISBN 0-393-06206-6.
  • Evenson, A. Edward (2000). The Telephone Patent Conspiracy of 1876: The Elisha Gray - Alexander Bell Controversy. North Carolina: McFarland. ISBN 0-7864-0883-9.
  • Baker, Burton H. (2000). The Gray Matter: The Forgotten Story of the Telephone. St. Joseph, Mi.: Telepress. ISBN 0-615-11329-X.
  • Coe, Lewis (1995). The Telephone and Its Several Inventors. North Carolina: McFarland Publishers. ISBN 0-7864-0138-9.
  • Patterson, Boyd Crumrine (January 1969). "The Story of Elisha Gray". Western Pennsylvania History. 52 (1): 29–41.
  • Dr. Lloyd W. Taylor, an Oberlin physics department head, began writing a Gray biography, but the book was never finished because of Taylor's accidental death in July 1948. Dr Taylor's unfinished manuscript is in the College Archives at Oberlin College.

External links

Gray's patents

Patent images in TIFF format

1876 in science

The year 1876 in science and technology involved some significant events, listed below.

Acoustic telegraphy

Acoustic telegraphy (also known as harmonic telegraphy) was a name for various methods of multiplexing (transmitting more than one) telegraph messages simultaneously over a single telegraph wire by using different audio frequencies or channels for each message. A telegrapher used a conventional Morse key to tap out the message in Morse code. The key pulses were transmitted as pulses of a specific audio frequency. At the receiving end a device tuned to the same frequency resonated to the pulses but not to others on the same wire.

Inventors who worked on the acoustic telegraph included Charles Bourseul, Thomas Edison, Elisha Gray, and Alexander Graham Bell. Their efforts to develop acoustic telegraphy, in order to reduce the cost of telegraph service, led to the invention of the telephone.Some of Thomas Edison's devices used multiple synchronized tuning forks tuned to selected audio frequencies and which opened and closed electrical circuits at the selected audio frequencies. Acoustic telegraphy was similar in concept to present-day FDMA, or Frequency Division Multiple Access, used with radio frequencies.

The word acoustic comes from the Greek akoustikos meaning hearing, as with hearing of sound waves in air. Acoustic telegraphy devices were electromechanical and made musical or buzzing or humming sound waves in air for a few feet. But the primary function of these devices was not to generate sound waves, but rather to generate alternating electrical currents at selected audio frequencies in wires which transmitted telegraphic messages electrically over long distances.

Alexander Graham Bell

Alexander Graham Bell ('Graham' pronounced ) (March 3, 1847 – August 2, 1922) was a Scottish-born scientist, inventor, engineer, and innovator who is credited with inventing and patenting the first practical telephone. He also founded the American Telephone and Telegraph Company (AT&T) in 1885.Bell's father, grandfather, and brother had all been associated with work on elocution and speech and both his mother and wife were deaf, profoundly influencing Bell's life's work. His research on hearing and speech further led him to experiment with hearing devices which eventually culminated in Bell being awarded the first U.S. patent for the telephone in 1876. Bell considered his invention an intrusion on his real work as a scientist and refused to have a telephone in his study.Many other inventions marked Bell's later life, including groundbreaking work in optical telecommunications, hydrofoils, and aeronautics. Although Bell was not one of the 33 founders of the National Geographic Society, he had a strong influence on the magazine while serving as the second president from January 7, 1898, until 1903.

Anthony Pollok

Anthony Pollok (1829 – July 4, 1898) was an American patent attorney who, with Marcellus Bailey, helped prepare Alexander Graham Bell's patents for the telephone and related inventions.

Elisha Gray and Alexander Bell telephone controversy

The Elisha Gray and Alexander Graham Bell controversy concerns the question of whether Gray and Bell invented the telephone independently. This issue is narrower than the question of who deserves credit for inventing the telephone, for which there are several claimants.

At issue are roles of each inventor's lawyers, the filing of patent documents, and allegations of theft.

Enos M. Barton

Enos Melancthon Barton (Dec 2, 1842 – May 3, 1916) was an American electrical engineer who, with Elisha Gray, co-founded Western Electric Manufacturing Company.

Graybar

Graybar is an American employee-owned corporation, based in Clayton, Missouri. It conducts a wholesale distribution business for electrical, communications and data networking products, and is a provider of related supply-chain management and logistics services. It is included on the Fortune 500 list of the largest United States corporations.Founded in 1869 in Cleveland, Ohio, by Elisha Gray and Enos Barton, it was the origin of the Western Electric Company. On December 11, 1925, it was separately incorporated as Graybar Electric Company, Inc.

Hazel Avenue/Prospect Avenue Historic District

The Hazel Avenue/Prospect Avenue Historic District is a historic area of Highland Park, Illinois, United States. It was home to some of Highland Park's most notable residents, including telephone inventor Elisha Gray.

History of the telephone

This history of the telephone chronicles the development of the electrical telephone, and includes a brief review of its predecessors.

Index of telephone-related articles

These are some of the links to articles that are telephone related.

See Category:Telephony for many more links

Invention of the telephone

The invention of the telephone was the culmination of work done by many individuals, and led to an array of lawsuits relating to the patent claims of several individuals and numerous companies. The first telephone was invented by Antonio Meucci, but Alexander Graham Bell is credited with the development of the first practical telephone.

List of scientific priority disputes

This is a list of priority disputes in science and science-related fields (such as mathematics).

Outline of telecommunication

The following outline is provided as an overview of and topical guide to telecommunication:

Telecommunication – the transmission of signals over a distance for the purpose of communication. In modern times, this process almost always involves the use of electromagnetic waves by transmitters and receivers, but in earlier years it also involved the use of drums and visual signals such as smoke, fire, beacons, semaphore lines and other optical communications.

Patent caveat

A patent caveat, often shortened to caveat, was a legal document filed with the United States Patent Office. Caveats were instituted by the U.S. Patent Act of 1836, but were discontinued in 1909, with the U.S. Congress abolishing the system formally in 1910. A caveat was similar to a patent application with a description of an invention and drawings, but without examination for patentable subject matter and without a requirement for patent claims. A patent caveat was an official notice of intention to file a patent application at a later date. A caveat expired after one year, but could be renewed by paying an annual fee of $10.Caveats were similar to provisional applications used today in the United States Patent and Trademark Office (USPTO) which also expire after one year. However, provisional applications today are non-renewable under any circumstances.

According to the Guide to the Practice of the Patent Office 1853, the primary objective of a caveat was to prevent the issuing of a rival patent for the same invention to a subsequent inventor. Before the issuing of a patent, the caveats filed within the preceding year were searched. If one was found for the same invention as the proposed patent, the Patent Office notified the holder of the caveat, who then had three months to submit a formal patent application with claims. If the two patent applications claimed the same invention, an interference would then be declared and neither patent could be issued until it was determined which was the first to invent.Perhaps the most famous example of such a conflict was on 14 February 1876, when Elisha Gray filed a patent caveat and Alexander Graham Bell filed a patent application on the same day, both relating to the telephone. Gray ended up abandoning his patent caveat, but the case was extremely controversial and continued in the courts for many years. A deaf patent examiner (Bell was well known for his work with the deaf and had a deaf wife) had met with Bell on the matter, and a handwritten marginal note including one of Gray's critical technical innovations appeared on Bell's patent, which had not been there on the original filing.This case contributed to the perception that patent caveats were potential leaks of valuable inventions to other applicants with friends in the Patent Office, without providing a solid legal recourse when confidentiality of the caveat was so abused. Gray did eventually win a judgement in a US court vindicating his claims, but long after: Bell was forever after known as inventor of the telephone. See the articles on Gray and Bell for details.The filing fee of $10 for a caveat was less costly than the filing fee $15 for a full patent application. As stated by the USPTO: "In 1861, the fee for obtaining a full patent was $35, of which $15 was to be paid at the time of application and $20 when the patent was granted. In 1922, the patent filing fee increased from $15 to $20." However the patent caveat fee remained $10 per year until the caveat system was abolished.

TIMARA

TIMARA (Technology in Music and Related Arts) is a program at the Oberlin Conservatory of Music notable for its importance in the history of electronic music. Established in 1967, TIMARA is well known as the world's first conservatory program in electronic music. Department alumni have included Cory Arcangel, Christopher Rouse, Dary John Mizelle, Dan Forden and Amy X Neuburg.The major in Technology in Music and Related Arts is intended for students who desire a career in which traditional musical skills and understanding are combined with the exploration of the very latest techniques for musical expression. The program prepares a student for specialized graduate study in computer music, digital media and new performance.

Telautograph

The telautograph, an analog precursor to the modern fax machine, transmits electrical impulses recorded by potentiometers at the sending station to servomechanisms attached to a pen at the receiving station, thus reproducing at the receiving station a drawing or signature made by the sender. It was the first such device to transmit drawings to a stationary sheet of paper; previous inventions in Europe had used rotating drums to make such transmissions.

The telautograph's invention is attributed to Elisha Gray, who patented it on July 31, 1888. Gray's patent stated that the telautograph would allow "one to transmit his own handwriting to a distant point over a two-wire circuit." It was the first facsimile machine in which the stylus was controlled by horizontal and vertical bars. The telautograph was first publicly exhibited at the 1893 World's Columbian Exposition held in Chicago.

While the patent schema's geometry implies vertical and horizontal coordinates, systems used in the 20th Century (and presumably before) had a different coordinate scheme, based on transmitting two angles.

In an 1888 interview in The Manufacturer & Builder (Vol. 24: No. 4: pages 85–86) Gray made this statement:

By my invention you can sit down in your office in Chicago, take a pencil in your hand, write a message to me, and as your pencil moves, a pencil here in my laboratory moves simultaneously, and forms the same letters and words in the same way. What you write in Chicago is instantly reproduced here in fac-simile. You may write in any language, use a code or cipher, no matter, a fac-simile is produced here. If you want to draw a picture it is the same, the picture is reproduced here. The artist of your newspaper can, by this device, telegraph his pictures of a railway wreck or other occurrences just as a reporter telegraphs his description in words.

By the end of the 19th century, the telautograph was modified by Foster Ritchie. Calling it the telewriter, Ritchie's version of the telautograph could be operated using a telephone line for simultaneous copying and speaking.The telautograph became very popular for the transmission of signatures over a distance, and in banks and large hospitals to ensure that doctors' orders and patient information were transmitted quickly and accurately.

Teleautograph systems were installed in a number of major railroad stations to relay hand-written reports of train movements from the interlocking tower to various parts of the station. The teleautograph network in Grand Central Terminal included a public display in the main concourse into the 1960s; a similar setup in Chicago Union Station remained in operation into the 1970s.

A Telautograph was used in 1911 to warn workers on the 10th floor about the Triangle Shirtwaist Factory fire that had broken out two floors below.

An example of a Telautograph machine writing script can be seen in the 1956 movie Earth vs the Flying Saucers as the output device for the mechanical translator.

Telautograph Corporation changed its name several times. In 1971, it was acquired by Arden/Mayfair. In 1993, Danka Industries purchased the company and renamed it Danka/Omnifax. In 1999, Xerox corporation purchased the company and called it the Omnifax division, which has since been absorbed by the corporation.

The Telephone Cases

The Telephone Cases, 126 U.S. 1 (1888), were a series of U.S. court cases in the 1870s and 1880s related to the invention of the telephone, which culminated in the 1888 decision of the United States Supreme Court upholding the priority of the patents belonging to Alexander Graham Bell. Those telephone patents were relied on by the American Bell Telephone Company and the Bell System—although they had also acquired critical microphone patents from Emile Berliner.

The objector (or plaintiff) in the notable Supreme Court case was initially the Western Union telegraph company, which was at the time a far larger and better financed competitor than American Bell Telephone. Western Union advocated several more recent patent claims of Daniel Drawbaugh, Elisha Gray, Antonio Meucci and Philip Reis in a bid to invalidate Alexander Graham Bell's master and subsidiary telephone patents dating back to March 1876. Had Western Union succeeded it would have immediately destroyed the Bell Telephone Company and then Western Union stood to become the world's largest telecommunications monopoly in Bell's place.

The U.S. Supreme Court came within one vote of overturning the Bell patent, thanks to the eloquence of lawyer Lysander Hill for the Peoples Telephone Company. In a lower court, the Peoples Telephone Company stock rose briefly during the early proceedings, but dropped after their claimant Daniel Drawbaugh took the stand and drawled: "I don’t remember how I came to it. I had been experimenting in that direction. I don’t remember of getting at it by accident either. I don’t remember of anyone talking to me of it".In this case the court affirmed several other lower court cases: Dolbear et al. v American Bell Tel. Co., 15 Fed. Rep 448, 17 Fed. Rep. 604, Molecular Te. Co. et al. v American Bell Tel. Co. 32 Fed. Rep 214, People's Tel. Co. et al. v American Bell Tel. Co., 22 Fed. Rep. 309 and 25 Fed. Rep. 725. Well reversing American Bell Tel Co. et al. v Molecular Tel. Co et al. 32 Fed Rep. 214.

Bell’s second fundamental patent expired on January 30, 1894, at which time the gates were then opened to independent telephone companies to compete with the Bell System. In all, the American Bell Telephone Company and its successor, AT&T, litigated 587 court challenges to its patents including five that went to the U.S. Supreme Court, and aside from two minor contract lawsuits, never lost a single one that was concluded with a final stage judgment.

Timeline of the telephone

This timeline of the telephone covers landline, radio, and cellular telephony technologies and provides many important dates in the history of the telephone.

Water microphone

A water microphone or water transmitter is based on Ohm's law that current in a wire varies inversely with the resistance of the circuit. The sound waves from a human voice cause a diaphragm to vibrate which causes a needle or rod to vibrate up and down in water that has been made conductive by a small amount of acid. As the needle or rod vibrates up and down in the water, the resistance of the water fluctuates which causes alternating current in the circuit. For this to work, the resistance of the water must vary substantially over the short distance the needle or rod vibrates. Acidulated water works well because only a small amount of acid is added. If one millimeter of acidulated water has a resistance of 100 ohms, two millimeters would have 200 ohms which would produce enough alternating current to transmit audio signals in thousands of feet of wire. Mercury will not work because the resistance of one millimeter of mercury is less than a tenth of an ohm and vibration of a needle in mercury would produce negligible alternating current.

Elisha Gray reasoned that a metal rod vibrating up and down in acidulated water would alternately lengthen and shorten the small distance between the bottom end of the rod and a metal plate at the bottom of the glass container holding the water. This is the invention described in Gray's caveat. When Alexander Bell's lawyer heard that Gray had described a vibrating rod in a liquid to vary the resistance, he added a claim for variable resistance in a draft of Bell's unfiled patent application and added an additional seven sentences that mentioned mercury as the liquid. The lawyer knew that Bell had experimented with a wire dipped in mercury to provide a flexible electrical switch.On March 10, 1876, when Bell and Watson tested their first successful water transmitter, Bell used a needle in the water to minimize the inertial mass moved by the diaphragm and relied on variable resistance in the meniscus of the water on the needle. The depth of the needle made little difference.

Other minor variations and improvements were made to the liquid microphone by Majoranna, Chambers, Vanni, Sykes, and Elisha Gray.

Although the water microphone was commercially impractical, the variable resistance feature inspired Thomas Edison to experiment with dry carbon (graphite and amorphous) to provide the variable resistance. The Edison transmitter with later improvements was used for more than 60 years.

History
Pioneers
Transmission
media
Network topology
and switching
Multiplexing
Networks

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.