In 1830 the great American scientist Professor Joseph Henry transmitted the
first practical electrical signal. A short time before Henry had invented
the first efficient electromagnet. He also concluded similar thoughts about
induction before Faraday but he didn’t publish them first. Henry’s place in
electrical history however, has always been secure, in particular for
showing that electromagnetism could do more than create current or pick up
heavy weights — it could communicate.
In a stunning demonstration in his Albany Academy classroom, Henry created
the forerunner of the telegraph. In the deemonstration, Henry first built an
electromagnet by winding an iron bar with several feet of wire. A pivot
mounted steel bar sat next to the magnet. A bell, in turn, stood next to
the bar. From the electromagnet Henry strung a mile of wire around the
inside of the classroom. He completed the circuit by connecting the ends of
the wires at a battery. Guess what happened? The steel bar swung toward the
magnet, of course, striking the bell at the same time. Breaking the
connection released thhe bar and it was free to strike again. And while
Henry did not pursue electrical signaling, he did help someone who did. And
that man was Samuel Finley Breese Morse.
For more information on Joseph Henry, visit the Joseph Henry Papers Project
at:
http://www.si.edu/archives/ihd/jhp/papers00.htm (e
From the December, 1963 American Heritage magazine, “a sketch of Henry’s
primitive telegraph, a dozen years before Morse, reveals the essential
components: an electromagnet activated by a distant battery, and a pivoted
iron bar that moves to ring a bell.” See the two books listed to the left
for more information.
In 1837 Samuel Morse invented the first workable telegraph, applied for its
patent in 1838, an
d was finally granted it in 1848. Joseph Henry helped Morse build a
telegraph relay or repeater that allowed long distance operation. The
telegraph later helped unite the country and eventually the world. Not a
professional inventor, Morse was nevertheless captivated by electrical
experiments. In 1832 he heard of Faraday’s recently published work on
inductance, and was given an electromagnet at the same time to ponder over.
An idea came too him and Morse quickly worked out details for his telegraph.
As depicted below, his system used a key (a switch) to make or break the
electrical circuit, a battery to produce power, a single line joining one
telegraph station to another and an electromagnetic receiver or sounder
that upon being turned on and off, produced a clicking noise. He completed
the package by devising the Morse code system of dots and dashes. A quick
key tap broke the circuit momentarily, transmitting a short pulse to a<
distant sounder, interpreted by an operator as a dot. A more lengthy break
produced a dash.
Telegraphy became big business
as it replaced messengers, the Pony Express, clipper ships and every other
slow paced means of communicating. The fact that service was limited to
Western Union offices or large firms seemed hardly a problem. After all,
communicating over long distances instantly was otherwise impossible. Yet
as the telegraph was perfected, man’s thoughts turned to speech over a
wire.
[pic]
Bell continued harmonic telegraph work through the fall of 1874. He wasn’t
making much progress but his tinkering gathered attention. Gardiner Greene
Hubbard, a prominent Boston lawyer and the president of the Clarke School
for The Deaf, became interested in Bell’s experiments. He and George
Sanders, a prosperous Salem businessman, both sensed Bell might make the
harmonic telegraph work. They also knew Bell the man, since Bell tutored
Hubbard’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, Hubbard
and Sanders began funding Bell. All three later signed a formal agreement
in February, 1875, giving Bell financial backing in return for equal shares
from any patents Bell developed. The trio got along but they would have
their problems. Sanders would co
before any return came to him. Hubbard, on the other hand, discouraged
Bell’s romance with his daughter until the harmonic telegraph was invented.
Bell, in turn, would risk his funding by working so hard on the telephone
and by getting engaged to Mabel without Hubbard’s permission.
In the spring of 1875, Bell’s experimenting picked up quickly with the help
of a talented young machinist named Thomas A. Watson. Bell feverishly
pursued the harmonic telegraph his backers wanted and the telephone which
was now his real interest. Seeking advice, Bell went to Washington D.C. On
March 1, 1875, Bell met with Joseph Henry, the great scientist and
inventor, then Secretary of the Smithsonian Institution. It was Henry,
remember, who pioneered electromagnetism and helped Morse with the
telegraph. Uninterested in Bell’s telegraph work, Henry did say Bell’s
ideas on transmitting speech electrically represented “the germ of a great
invention.” He urged Bell to drop all other work and get on with developing
the telephone. Bell said he feared he lacked the necessary electrical
knowledge, to which the old man replied, “Get it!” [Grosvenor and Wesson]
Bell quit pursuing the harmonic telegraph, at least in spirit, and began
working full time on the telephone.
After lengthy experimenting in the spring of 1875, Bell told Watson “If I
can get a mechanism wh
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] He
communicated the same idea in a letter to Hubbard, who remained unimpressed
and urged Bell to work harder on the telegraph. But having at last
articulated the principle of variable resistance, Bell was getting much
closer.
On June 2, 1875, Bell and Watson were testing the harmonic telegraph when
Bell heard a sound come through the receiver. Instead of transmitting a
pulse, which it had refused to do in any case, the telegraph passed on the
sound of Watson plucking a tuned spring, one of many set at different
pitches. How could that be? Their telegraph, like all others, turned
current on and off. But in this instance, a contact screw was set too
tightly, allowing current to run continuously, the essential element needed
to transmit speech. Bell realized what happened and had Watson build a
telephone the next day based on this discovery. The Gallows telephone, so
called for its distinctive frame, substituted a diaphragm for the spring.
Yet it didn’t work. A few odd sounds were transmitted, yet nothing more. No
speech. Disheartened, tired, and running out of funds, Bell’s experimenting
slowed through the remainder of 1875.
[pic]
During the winter of 1875 and 1876 Bell continued experimenting while
writing a telephone patent application. Although he hadn’t developed a
successful telephone, he felt he could describe how it could be done. With
his ideas and methods protected he could then focus on making it work.
Fortunately for Bell and many others, the Patent Office in 1870 dropped its
requirement that a working model accompany a patent application. On
February 14, 1876, Bell’s patent application was filed by his attorney. It
came only hours before Elisha Gray filed his Notice of Invention for a
telephone.
Mystery still surrounds Bell’s application and what happened that day. In
particular, the key point to Bell’s application, the principle of variable
resistance, was scrawled in a margin, almost as an afterthought. Some think
Bell was told of Gray’s Notice then allowed to change his application. That
was never proved, despite some 600 lawsuits that would eventually challenge
the patent. Finally, on March 10, 1876, one week after his patent was
allowed, in Boston, Massachusetts, at his lab at 5 Exeter Place, Bell
succeeded in transmitting speech. He was not yet 30. Bell used a liquid
transmitter, something he hadn’t outlined in his patent or even tried
before, but something that was described in Gray’s Notice.
Bell’s patent, U.S. Number 174,465, has been called the most valuable ever
issued. If you have QuickTime or another way to view .tif files you can
view the document at the United States Patent and Trademark site (external
link). Search for it by the number. Each page of the six page document is
about 230K. And yes, it is very hard to follow. Patents are meant to
protect ideas, not necessarily to explain them . . .
The Watson-built telephone looked odd and acted strangely. Bellowing into
the funnel caused a small disk or diaphragm at the bottom to move. This
disk 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 wire
moved up and down it changed the resistance within the liquid. This now
varying current was then sent to the receiver, causing its membrane to
vibrate and thereby produce sound. This telephone wasn’t quite practical;
it got speech across, but badly. Bell soon improved it by using an
electromagnetic 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 worked
Simplified diagram of Bell’s liquid transmitter. The diaphragm vibrated
with sound waves, causing a conducting rod to move up and down in a cup of
acid water. Battery supplied power electrified the cup of acid. As the rod
rose and fell it changed the circuit’s resistance. This caused the line
current to the receiver (not shown) to fluctuate, which in turn caused the
membrane of the receiver to vibrate, producing sound.
This transmitter was quickly dropped in favor of voice powered or induced
models. These transmitted speech on the weak electro-magnetic force that
the transmitter and receiver’s permanent magnets produced.
It was not until 1882, with the introduction of the Blake transmitter, that
Bell telephones once again used line power. The so called local battery
circuit used a battery supplied at the phone to power the line and take
speech to the local switch. Voice powered phones did not go away
completely, as some systems continued to be used for critical applications,
those which may have been threatened by spark. In 1964 NASA used a voice
powered system described as follows:
“A network of 24 channels with a total of more than 450 sound powered
telephones, which derive their power solely from the human voice, provide
the communications between the East Area central blockhouse (left) and the
various test stands at NASA’s George C. Marshall Space Flight Center here.
. .” The complete article is here:
[pic]
IV. The Telephone Evolves
At this point telephone history becomes fragmented and hard to follow. Four
different but related stories begin: (1) the further history of the
telephone instrument and all its parts, (2) the history of the telephone
business, (3) the history of telephone related technology and (4) the
history of the telephone system. Due to limited space I can cover only some
major North American events. Of these, the two most important developments
were the invention of the vacuum tube and the transistor; today’s telephone
system could not have been built without them.
[pic]
Progress came slowly after the original invention. Bell and Watson worked
constantly on improving the telphone’s range. They made their longest call
to date on October 9, 1876. It was a distance of only two miles, but they
were so overjoyed that later that night they celebrated, doing so much
began dancing that their landlady threatened to throw them out. Watson
later recalled “Bell . . . had a habit of celebrating by what he called a
war dance and I had got so exposed at it that I could do it quite as well
as he could.” [Watson] The rest of 1876, though, was difficult for Bell and
his backers.
Bell and Watson improved the telephone and made better models of it, but
these changes weren’t enough to turn the telephone from a curiosity into a
needed appliance. Promoting and developing the telephone proved far harder
than Hubbard, Sanders, or Bell expected. No switchboards existed yet, the
telephones were indeed crude and transmission quality was poor. Many
questioned 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. In
addition, other people filed applications for telephones and transmitters
after Bell’s patent was issued. Most claimed Bell’s patent couldn’t produce
a working telephone or that they had a prior claim. Litigation loomed.
Fearing financial collapse, Hubbard and Sanders offered in the fall of 1876
to 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 and
corrections)
In 1876 Ericsson begins.
[pic]
In1878, the Butterstamp telephone came into use. This telephone combined
the receiver and transmitter into one handheld unit. You talked into one
end, turned the instrument round and listened to the other end. People got
confused with this clumsy arrangement, consequently, a telephone with a
second transmitter and receiver unit was developed in the same year. You
could use either one to talk or listen and you didn’t have to turn them
around. This wall set used a crank to signal the operator.
[pic]
The Butterstamp telephone.
On August 1, 1878 Thomas Watson filed for a ringer patent. Similar to
Henry’s classroom doorbell, a hammer operated by an electromagnet struck
two bells. Turning a crank on the calling telephone spun a magneto,
producing an alternating or ringing current. Previously, people used a
crude thumper to signal the called party, hoping someone would be around to
hear it. The ringer was an immediate success. Bell himself became more
optimistic about the telephone’s future, prophetically writing in 1878 “I
believe that in the future, wires will unite the head offices of the
Telephone Company in different cities, and that a man in one part of the
country 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 New
Englanders willing to invest but unwilling to do business outside their
area. Needing the funding, the Bell Telephone Company reorganized in June,
1878, forming a new Bell Telephone Company as well as the New England
Telephone Company, a forerunner of the strong regional Bell companies to
come. 10,755 Bell phones were now in service. Reorganizing passed control
to an executive committee, ending Hubbard’s stewardship but not his overall
vision. 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 early
1879 the company reorganized once again, under pressure from patent suits
and competition from other companies selling phones with Edison’s superior
transmitter. Capitalization was $850,000. William H. Forbes was elected to
head the board of directors. He soon restructured it to embrace all Bell
interests into a single company, the National Bell Company, incorporated on
March 13, 1879. Growth was steady enough, however, that in late 1879 the
first telephone numbers were used.
On November 10, 1879 Bell won its patent infringement suit against Western
Union in the United States Supreme Court. In the resulting settlement,
Western Union gave up its telephone patents and the 56,000 phones it
managed, in return for 20% of Bell rentals for the 17 year life of Bell’s
patents. It also retained its telegraph business as before. This decision
so enlarged National Bell that a new entity with a new name, American Bell
Company, was created on February 20, 1880, capitalized with over seven
million dollars. Bell now managed 133,000 telephones. As Chief Operating
Officer, Theodore Vail began creating the Bell System, composed of regional
companies offering local service, a long distance company providing toll
service, and a manufacturing arm providing equipment. For the manufacturer
he turned to a previous company rival. In 1880 Vail started buying Western
Electric stock and took controlling interest on November, 1881. The
takeover was consummated on February 26, 1882, with Western Electric giving
up its remaining patent rights as well as agreeing to produce products
exclusively for American Bell. It was not until 1885 that Vail would form
his long distance telephone company. It was called AT&T.
[pic]
On July 19, 1881 Bell was granted a patent for the metallic circuit, the
concept of two wires connecting each telephone. Until that time a single
iron wire connected telephone subscribers, just like a telegraph circuit. A
conversation works over one wire since grounding each end provides a
complete path for an electrical circuit. But houses, factories and the
telegraph system were all grounding their electrical circuits using the
same earth the telephone company employed. A huge amount of static and
noise was consequently introduced by using a grounded circuit. A metallic
circuit, on the other hand, used two wires to complete the electrical
circuit, avoiding the ground altogether and thus providing a better
sounding call.
Depending on local conditions and economies, some independent telephone
companies did not introduce two wire for decades after. Consider this
example from the Magazine Telephone Company of central Arkansas: “After the
end of WW II, the R.E.A. System was introduced to the area. This
electrification project induced noise into the one wire magneto system that
was currently in use by the Telephone Company. Henry [Stone] converted the
magneto system to a new system called common battery. Instead of just one
wire, common battery required two metallic wires for each circuit.”
For a short but well detailed history of an independent telco, visit the
Magazine Telephone Company:
On February 28, 1885 AT&T was born. Capitalized on only $100,000, American
Telephone and Telegraph provided long distance service for American Bell.
Only local telephone companies operating under Bell granted licenses could
connect to AT&T’s long distance network. Vail thought this would continue
the Bell System’s virtual monopoly after its key patents expired in the
1890s. He reasoned the independents could not compete since they would be
isolated and without long distance lines. With licensed companies providing
local service, Western Electric manufacturing equipment and AT&T providing
long 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. Despite
decades of dreaming, development and desire by Bell scientists, technicians
and marketing wonks, the videotelephone never found a market. [pic]
GTE was then a poorly managed conglomerate of 23 regional phone companies
and a maker of, among other things, televisions and light bulbs. They had
their successes and failures. One notable achievement is below.
“Introducing a crimestopper so advanced Dick Tracy doesn’t have it yet.”
[pic]
In1971 General Telephone and Electronics (GTE Sylvania) introduced a data
system called Digicom. It let dispatchers identifying patrol car locations
on a screen, and allowed officers to run license plate checks. When a
patrolman touched a spot on the digicom screen it lit up the same spot on
the dispatcher’s map. Produced by their Sociosystems Products Organization,
I do not know how many units were actually installed by GTE, but it
certainly foreshadowed later developments. Today many police departments
use cellular digital packet data (CDPD) to run plates and communicate in
text with their dispatchers. CDPD runs on existing cellular networks, with
data rates no more that 9.6 or 19.2 Kbs, adequate for most purposes but
slow when you consider that in the year 2000, 29 years after this system
was introduced, we are still laboring with creeping data rates. Click on
the image above or here to get the full picture and story. (It’s a huge
graphic file so be careful: 364K)
1968. Even the astute Japanese fell victim to developing picturephones as
this unflattering photograph shows, this model was probably developed by
Nippon Telephone and Telegraph
In 1982 the Bell System had grown to an unbelievable 155 billion dollars in
assets (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 carefully
thought up plan from within. Essentially, the Bell System divested itself.
Kaunas Technology University
Darbą atliko:Rima Jakučionytė,
Nerijus Kalinka
Tikrino:dėstytoja V.Šeštokova