In 1830 the great American scientist Professor Joseph Henry transmitted thefirst practical electrical signal. A short time before Henry had inventedthe first efficient electromagnet. He also concluded similar thoughts aboutinduction before Faraday but he didn’t publish them first. Henry’s place inelectrical history however, has always been secure, in particular forshowing that electromagnetism could do more than create current or pick upheavy weights — it could communicate.
In a stunning demonstration in his Albany Academy classroom, Henry createdthe forerunner of the telegraph. In the demonstration, Henry first built anelectromagnet by winding an iron bar with several feet of wire. A pivotmounted steel bar sat next to the magnet. A bell, in turn, stood next tothe bar. From the electromagnet Henry strung a mile of wire around theinside of the classroom. He completed the circuit by connecting the ends ofthe wires at a battery. Guess what happened? The steel bar swung toward themagnet, of course, striking the bell at the same time. Breaking theconnection released the bar and it was free to strike again. And whileHenry did not pursue electrical signaling, he did help someone who did. Andthat man was Samuel Finley Breese Morse.For more information on Joseph Henry, visit the Joseph Henry Papers Projectat:http://www.si.edu/archives/ihd/jhp/papers00.htm (external link)
From the December, 1963 American Heritage magazine, “a sketch of Henry’sprimitive telegraph, a dozen years before Morse, reveals the essentialcomponents: an electromagnet activated by a distant battery, and a pivotediron bar that moves to ring a bell.” See the two books listed to the leftfor more information.
In 1837 Samuel Morse invented the first workable telegraph, applied for itspatent in 1838, and was finally granted it in 1848. Joseph Henry helped Morse build a
telegraph relay or repeater that allowed long distance operation. Thetelegraph later helped unite the country and eventually the world. Not aprofessional inventor, Morse was nevertheless captivated by electricalexperiments. In 1832 he heard of Faraday’s recently published work oninductance, and was given an electromagnet at the same time to ponder over.An idea came to him and Morse quickly worked out details for his telegraph.As depicted below, his system used a key (a switch) to make or break theelectrical circuit, a battery to produce power, a single line joining onetelegraph station to another and an electromagnetic receiver or sounderthat upon being turned on and off, produced a clicking noise. He completedthe package by devising the Morse code system of dots and dashes. A quickkey tap broke the circuit momentarily, transmitting a short pulse to adistant sounder, interpreted by an operator as a dot. A more lengthy breakproduced a dash. Telegraphy became big businessas it replaced messengers, the Pony Express, clipper ships and every otherslow paced means of communicating. The fact that service was limited toWestern Union offices or large firms seemed hardly a problem. After all,communicating over long distances instantly was otherwise impossible. Yetas the telegraph was perfected, man’s thoughts turned to speech over awire.
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Bell continued harmonic telegraph work through the fall of 1874. He wasn’tmaking much progress but his tinkering gathered attention. Gardiner GreeneHubbard, a prominent Boston lawyer and the president of the Clarke Schoolfor The Deaf, became interested in Bell’s experiments. He and GeorgeSanders, a prosperous Salem businessman, both sensed Bell might make theharmonic telegraph work. They also knew Bell the man, since Bell tutoredHubbard’s daughter and he was helping Sander’s deaf five year old son learn
to speak.In October, 1874, Green went to Washington D.C. to conduct a patent search.Finding no invention similar to Bell’s proposed harmonic telegraph, Hubbardand Sanders began funding Bell. All three later signed a formal agreementin February, 1875, giving Bell financial backing in return for equal sharesfrom any patents Bell developed. The trio got along but they would havetheir problems. Sanders would court bankruptcy by investing over $100,000before any return came to him. Hubbard, on the other hand, discouragedBell’s romance with his daughter until the harmonic telegraph was invented.Bell, in turn, would risk his funding by working so hard on the telephoneand by getting engaged to Mabel without Hubbard’s permission.
In the spring of 1875, Bell’s experimenting picked up quickly with the helpof a talented young machinist named Thomas A. Watson. Bell feverishlypursued the harmonic telegraph his backers wanted and the telephone whichwas now his real interest. Seeking advice, Bell went to Washington D.C. OnMarch 1, 1875, Bell met with Joseph Henry, the great scientist andinventor, then Secretary of the Smithsonian Institution. It was Henry,remember, who pioneered electromagnetism and helped Morse with thetelegraph. Uninterested in Bell’s telegraph work, Henry did say Bell’sideas on transmitting speech electrically represented “the germ of a greatinvention.” He urged Bell to drop all other work and get on with developingthe telephone. Bell said he feared he lacked the necessary electricalknowledge, to which the old man replied, “Get it!” [Grosvenor and Wesson]Bell quit pursuing the harmonic telegraph, at least in spirit, and beganworking full time on the telephone.
After lengthy experimenting in the spring of 1875, Bell told Watson “If Ican get a mechanism which will make a current of electricity vary in its
intensity as the air varies in density when a sound is passing through it,I can telegraph any sound, even the sound of speech.” [Fagen] Hecommunicated the same idea in a letter to Hubbard, who remained unimpressedand urged Bell to work harder on the telegraph. But having at lastarticulated the principle of variable resistance, Bell was getting muchcloser.On June 2, 1875, Bell and Watson were testing the harmonic telegraph whenBell heard a sound come through the receiver. Instead of transmitting apulse, which it had refused to do in any case, the telegraph passed on thesound of Watson plucking a tuned spring, one of many set at differentpitches. How could that be? Their telegraph, like all others, turnedcurrent on and off. But in this instance, a contact screw was set tootightly, allowing current to run continuously, the essential element neededto transmit speech. Bell realized what happened and had Watson build atelephone the next day based on this discovery. The Gallows telephone, socalled for its distinctive frame, substituted a diaphragm for the spring.Yet it didn’t work. A few odd sounds were transmitted, yet nothing more. Nospeech. Disheartened, tired, and running out of funds, Bell’s experimentingslowed through the remainder of 1875.
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During the winter of 1875 and 1876 Bell continued experimenting whilewriting a telephone patent application. Although he hadn’t developed asuccessful telephone, he felt he could describe how it could be done. Withhis ideas and methods protected he could then focus on making it work.Fortunately for Bell and many others, the Patent Office in 1870 dropped itsrequirement that a working model accompany a patent application. OnFebruary 14, 1876, Bell’s patent application was filed by his attorney. Itcame only hours before Elisha Gray filed his Notice of Invention for a
telephone.Mystery still surrounds Bell’s application and what happened that day. Inparticular, the key point to Bell’s application, the principle of variableresistance, was scrawled in a margin, almost as an afterthought. Some thinkBell was told of Gray’s Notice then allowed to change his application. Thatwas never proved, despite some 600 lawsuits that would eventually challengethe patent. Finally, on March 10, 1876, one week after his patent wasallowed, in Boston, Massachusetts, at his lab at 5 Exeter Place, Bellsucceeded in transmitting speech. He was not yet 30. Bell used a liquidtransmitter, something he hadn’t outlined in his patent or even triedbefore, but something that was described in Gray’s Notice.
Bell’s patent, U.S. Number 174,465, has been called the most valuable everissued. If you have QuickTime or another way to view .tif files you canview the document at the United States Patent and Trademark site (externallink). Search for it by the number. Each page of the six page document isabout 230K. And yes, it is very hard to follow. Patents are meant toprotect ideas, not necessarily to explain them . . .
The Watson-built telephone looked odd and acted strangely. Bellowing intothe funnel caused a small disk or diaphragm at the bottom to move. Thisdisk was, in turn, attached to a wire floating in an acid-filled metal cup.A wire attached to the cup in turn led to a distant receiver. As the wiremoved up and down it changed the resistance within the liquid. This nowvarying current was then sent to the receiver, causing its membrane tovibrate and thereby produce sound. This telephone wasn’t quite practical;it got speech across, but badly. Bell soon improved it by using anelectromagnetic transmitter, a metal diaphragm and a permanent magnet. The
telephone had been invented. Now it was time for it to evolve.[pic]How the first telephone workedSimplified diagram of Bell’s liquid transmitter. The diaphragm vibratedwith sound waves, causing a conducting rod to move up and down in a cup ofacid water. Battery supplied power electrified the cup of acid. As the rodrose and fell it changed the circuit’s resistance. This caused the linecurrent to the receiver (not shown) to fluctuate, which in turn caused themembrane of the receiver to vibrate, producing sound.
This transmitter was quickly dropped in favor of voice powered or inducedmodels. These transmitted speech on the weak electro-magnetic force thatthe transmitter and receiver’s permanent magnets produced.
It was not until 1882, with the introduction of the Blake transmitter, thatBell telephones once again used line power. The so called local batterycircuit used a battery supplied at the phone to power the line and takespeech to the local switch. Voice powered phones did not go awaycompletely, as some systems continued to be used for critical applications,those which may have been threatened by spark. In 1964 NASA used a voicepowered system described as follows:
“A network of 24 channels with a total of more than 450 sound poweredtelephones, which derive their power solely from the human voice, providethe communications between the East Area central blockhouse (left) and thevarious test stands at NASA’s George C. Marshall Space Flight Center here.. .” The complete article is here:
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IV. The Telephone Evolves
At this point telephone history becomes fragmented and hard to follow. Fourdifferent but related stories begin: (1) the further history of thetelephone instrument and all its parts, (2) the history of the telephonebusiness, (3) the history of telephone related technology and (4) thehistory of the telephone system. Due to limited space I can cover only some
major North American events. Of these, the two most important developmentswere the invention of the vacuum tube and the transistor; today’s telephonesystem could not have been built without them.[pic]
Progress came slowly after the original invention. Bell and Watson workedconstantly on improving the telphone’s range. They made their longest callto date on October 9, 1876. It was a distance of only two miles, but theywere so overjoyed that later that night they celebrated, doing so muchbegan dancing that their landlady threatened to throw them out. Watsonlater recalled “Bell . . . had a habit of celebrating by what he called awar dance and I had got so exposed at it that I could do it quite as wellas he could.” [Watson] The rest of 1876, though, was difficult for Bell andhis backers.
Bell and Watson improved the telephone and made better models of it, butthese changes weren’t enough to turn the telephone from a curiosity into aneeded appliance. Promoting and developing the telephone proved far harderthan Hubbard, Sanders, or Bell expected. No switchboards existed yet, thetelephones were indeed crude and transmission quality was poor. Manyquestioned why anyone needed a telephone. And despite Bell’s patent,broadly covering the entire subject of transmitting speech electrically,many companies sprang up to sell telephones and telephone service. Inaddition, other people filed applications for telephones and transmittersafter Bell’s patent was issued. Most claimed Bell’s patent couldn’t producea working telephone or that they had a prior claim. Litigation loomed.Fearing financial collapse, Hubbard and Sanders offered in the fall of 1876to sell their telephone patent rights to Western Union for $100,000.Western Union refused.(Special thanks to William Farkas of Ontario, Canada for his remarks andcorrections)
In 1876 Ericsson begins.
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In1878, the Butterstamp telephone came into use. This telephone combinedthe receiver and transmitter into one handheld unit. You talked into oneend, turned the instrument round and listened to the other end. People gotconfused with this clumsy arrangement, consequently, a telephone with asecond transmitter and receiver unit was developed in the same year. Youcould use either one to talk or listen and you didn’t have to turn themaround. This wall set used a crank to signal the operator.
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The Butterstamp telephone.
On August 1, 1878 Thomas Watson filed for a ringer patent. Similar toHenry’s classroom doorbell, a hammer operated by an electromagnet strucktwo bells. Turning a crank on the calling telephone spun a magneto,producing an alternating or ringing current. Previously, people used acrude thumper to signal the called party, hoping someone would be around tohear it. The ringer was an immediate success. Bell himself became moreoptimistic about the telephone’s future, prophetically writing in 1878 “Ibelieve that in the future, wires will unite the head offices of theTelephone Company in different cities, and that a man in one part of thecountry may communicate by word of mouth with another in a distant place.”
Subscribers, meanwhile, grew steadily but slowly. Sanders had invested$110,000 by early 1878 without any return. He located a group of NewEnglanders willing to invest but unwilling to do business outside theirarea. Needing the funding, the Bell Telephone Company reorganized in June,1878, forming a new Bell Telephone Company as well as the New EnglandTelephone Company, a forerunner of the strong regional Bell companies tocome. 10,755 Bell phones were now in service. Reorganizing passed controlto an executive committee, ending Hubbard’s stewardship but not his overallvision. For Hubbard’s last act was to hire a far seeing general manager
named Theodore Vail. But the corporate shuffle wasn’t over yet. In early1879 the company reorganized once again, under pressure from patent suitsand competition from other companies selling phones with Edison’s superiortransmitter. Capitalization was $850,000. William H. Forbes was elected tohead the board of directors. He soon restructured it to embrace all Bellinterests into a single company, the National Bell Company, incorporated onMarch 13, 1879. Growth was steady enough, however, that in late 1879 thefirst telephone numbers were used.On November 10, 1879 Bell won its patent infringement suit against WesternUnion in the United States Supreme Court. In the resulting settlement,Western Union gave up its telephone patents and the 56,000 phones itmanaged, in return for 20% of Bell rentals for the 17 year life of Bell’spatents. It also retained its telegraph business as before. This decisionso enlarged National Bell that a new entity with a new name, American BellCompany, was created on February 20, 1880, capitalized with over sevenmillion dollars. Bell now managed 133,000 telephones. As Chief OperatingOfficer, Theodore Vail began creating the Bell System, composed of regionalcompanies offering local service, a long distance company providing tollservice, and a manufacturing arm providing equipment. For the manufacturerhe turned to a previous company rival. In 1880 Vail started buying WesternElectric stock and took controlling interest on November, 1881. Thetakeover was consummated on February 26, 1882, with Western Electric givingup its remaining patent rights as well as agreeing to produce productsexclusively for American Bell. It was not until 1885 that Vail would formhis long distance telephone company. It was called AT&T.[pic]On July 19, 1881 Bell was granted a patent for the metallic circuit, theconcept of two wires connecting each telephone. Until that time a singleiron wire connected telephone subscribers, just like a telegraph circuit. A
conversation works over one wire since grounding each end provides acomplete path for an electrical circuit. But houses, factories and thetelegraph system were all grounding their electrical circuits using thesame earth the telephone company employed. A huge amount of static andnoise was consequently introduced by using a grounded circuit. A metalliccircuit, on the other hand, used two wires to complete the electricalcircuit, avoiding the ground altogether and thus providing a bettersounding call.Depending on local conditions and economies, some independent telephonecompanies did not introduce two wire for decades after. Consider thisexample from the Magazine Telephone Company of central Arkansas: “After theend of WW II, the R.E.A. System was introduced to the area. Thiselectrification project induced noise into the one wire magneto system thatwas currently in use by the Telephone Company. Henry [Stone] converted themagneto system to a new system called common battery. Instead of just onewire, common battery required two metallic wires for each circuit.”For a short but well detailed history of an independent telco, visit theMagazine Telephone Company:
On February 28, 1885 AT&T was born. Capitalized on only $100,000, AmericanTelephone and Telegraph provided long distance service for American Bell.Only local telephone companies operating under Bell granted licenses couldconnect to AT&T’s long distance network. Vail thought this would continuethe Bell System’s virtual monopoly after its key patents expired in the1890s. He reasoned the independents could not compete since they would beisolated and without long distance lines. With licensed companies providinglocal service, Western Electric manufacturing equipment and AT&T providinglong distance, Vail’s structuring of the Bell System was now complete.
In 1964 the Bell System put its star crossed videotelephone into limited
commercial service between New York, Washington and Chicago. Despitedecades of dreaming, development and desire by Bell scientists, techniciansand marketing wonks, the videotelephone never found a market. [pic]GTE was then a poorly managed conglomerate of 23 regional phone companiesand a maker of, among other things, televisions and light bulbs. They hadtheir successes and failures. One notable achievement is below.
“Introducing a crimestopper so advanced Dick Tracy doesn’t have it yet.”
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In1971 General Telephone and Electronics (GTE Sylvania) introduced a datasystem called Digicom. It let dispatchers identifying patrol car locationson a screen, and allowed officers to run license plate checks. When apatrolman touched a spot on the digicom screen it lit up the same spot onthe dispatcher’s map. Produced by their Sociosystems Products Organization,I do not know how many units were actually installed by GTE, but itcertainly foreshadowed later developments. Today many police departmentsuse cellular digital packet data (CDPD) to run plates and communicate intext with their dispatchers. CDPD runs on existing cellular networks, withdata rates no more that 9.6 or 19.2 Kbs, adequate for most purposes butslow when you consider that in the year 2000, 29 years after this systemwas introduced, we are still laboring with creeping data rates. Click onthe image above or here to get the full picture and story. (It’s a hugegraphic file so be careful: 364K)
1968. Even the astute Japanese fell victim to developing picturephones asthis unflattering photograph shows, this model was probably developed byNippon Telephone and TelegraphIn 1982 the Bell System had grown to an unbelievable 155 billion dollars inassets (256 billion in today’s dollars), with over one million employees.By comparison, Microsoft in 1998 had assets of around 10 billion dollars.On August 24, 1982, after seven years of wrangling, the Bell System was
split apart, succumbing to government pressure from without and a carefullythought up plan from within. Essentially, the Bell System divested itself.Kaunas Technology University
Darbą atliko:Rima Jakučionytė,
Nerijus Kalinka
Tikrino:dėstytoja V.Šeštokova