Telephone history
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Telephone history

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 demonstration, 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 the 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 (external link)

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 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 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 court bankruptcy by investing over $100,000

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 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] 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

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