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Speaking through a wire
One tells that a few years after the introduction of the telegraph
the operators entertained themselves, when there was not much to
do, marking the compass of the folksongs of the day with its telegraphic
manipulators. Many operators got to be so capable in this pastime,
that they easily recognized the song by the tips of the receiver
in the other end of the line. In 1854, Charles Bourseul, in France,
suggested the idea of connecting a diaphragm to one of contacts
of a telegraphic line, so that the vibrations of the diaphragm when
opening and closing the circuit could produce intermittent currents
in the line of the same frequency that the sound waves that acted
on the diaphragm. He explained in addition that a similar diaphragm,
placed near an electromagnet in the other end of the line, should
vibrate by the magnetic attraction and reproduce the primitive sound.
No practical application was derived from this idea; but in 1861,
Philipp Reis (1834 - 1874), in Germany, constructed a device that
made practically the same intention. Reis denominated to his instrument
"telephone" and he was able to transmit musical sounds
with great success; but the transmission of the language was imperfect
in general. We will see in the later developments of the idea, that
a small alteration on the telephone of Reis had made it work perfectly.
In 1885 a monument to the memory of the inventor in his native city
of Gelnhausen was elevated .
In 1874, Alexander Graham Bell, professor at the University
of Boston, was interested in the study of the "multiplex"
telegraph devices , a popular subject in that time, because of the
fast development of the telegraphic industry. He conceived the idea
to transmitting several dispatches by a single wire, by means of
a certain number of pairs of steel springs. We will give a brief
explanation of the Bell's harmonic telegraph , because this one
represented an important link in the development of the telephone.
When the manipulator in A is lowered, the spring of the transmitting
station is attracted by the electromagnet; but when it moves it
opens the circuit, so the spring will vibrate continuously with
its natural frequency while the manipulator is low. As an intermittent
current takes place in the telegraphic line with the same frequency
that the one of the vibrant spring , another spring in B, the other
end of the line, with the same frequency of vibration, would be
attracted intermittently by the electromagnet .Therefore it is possible
to be obtained that two similar springs vibrate to the unisonous
in the ends of a telegraphic line. Bell thought that it was possible
to connect to the ends of a simple telegraphic line a certain number
of these units so that several dispatches could be sent at the same
time , if each pair of springs were fit to a different vibration
frequency. Although he constructed different models of these multiple
telegraphs, he never obtained that they work satisfactorily.
The telephone, an accidental
discovery
During these tests Bell commented to several friends the possibility
of transmitting electrically the spoken word, and it is evident
that he knew the attempts done by Reis in that field. It was advised
to him, nevertheless, that he perseverase in the development of
his harmonic telegraph; and the talking telephone invented by Bell
owes partly its existence to an accidental discovery done during
these telegraphic experiments. His mechanic, Thomas A. Watson,
informed that he was in charge the June 2 , 1875 to make vibrate
one of the spring in the transmitting station of a short line in
an attic in Court street, in Boston, while the professor Bell was
attaching a spring in another room in the other end of the line.
Two parts that were put accidentally in contact by the vibration
of the springs got to solder themselves by the heat of the spark
that jumped between them, and Watson, treating to break this union
pulled the springs several times.
Professor Bell hurried from the
immediate room shouting: "What were you doing?",
Bell had heard the exact sound of the emitting spring reproduced
by the spring in the receiving end of the line.
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