Pages: (1)_(2)_(3)_(4)_(5)_(6)_(7)_(8)_(9) (10)
(11) (Communicating)
(Soundwaves) (Life
at Western Electric)
Tom Farley's Telephone
History Series
Credit me as the author, no restrictions on reproducing this work. Cite date as 1998 to 2006
Telephone History
Part 1 -- to 1830
"We picture inventors
as heroes with the genius to recognize and solve a society's
problems. In reality, the greatest inventors have been tinkerers
who loved tinkering for its own sake and who then had to figure
out what, if anything, their devices might be good for."
Jared Diamond
I. Introduction
On March 10, 1876, in Boston, Massachusetts, Alexander Graham
Bell invented the telephone. Thomas Watson fashioned the device
itself; a crude thing made of a wooden stand, a funnel, a cup
of acid, and some copper wire. But these simple parts and the
equally simple first telephone call -- "Mr. Watson, come
here, I want you!" -- belie a complicated past. Bell filed
his application just hours before his competitor, Elisha Gray,
filed notice to soon patent a telephone himself. What's more,
though neither man had actually built a working telephone, Bell
made his telephone operate three weeks later using ideas outlined
in Gray's Notice of Invention, methods Bell did not propose in
his own patent.
" .
. . an inspired black-haired Scotsman of twenty eight, on the
eve of marriage, vibrant and alive to new ideas." Alexander
Graham Bell : The Life and Times of the Man Who Invented the
Telephone
|
Intrigue aside for now, the story of the telephone is the
story of invention itself. Bell developed new and original ideas
but did so by building on older ideas and developments. Bell
succeeded specifically because he understood acoustics, the study
of sound, and something about electricity. Other inventors knew
electricity well but little of acoustics. The telephone is a
shared accomplishment among many pioneers, therefore, although
the credit and rewards were not shared equally. That, too, is
often the story of invention.
Telephone comes from the Greek
word tele, meaning from afar, and phone, meaning voice or voiced sound. Generally, a telephone is any device which conveys sound over a distance. A string telephone, a megaphone, or a speaking tube might be considered telephonic instruments but for our purposes they are not telephones. These transmit sound mechanically and not electrically. How's that?
Speech is sound in motion. Talking
produces acoustic pressure. Speaking into the can of a string
telephone, for example, makes the line vibrate, causing sound
waves to travel from one end of the stretched line to the other.
A telephone by comparison, reproduces sound by electrical means.
What the Victorians called "talking by lightning."
A standard dictionary defines the telephone as "an apparatus
for reproducing sound, especially that of the voice, at a great
distance, by means of electricity; consisting of transmitting
and receiving instruments connected by a line or wire which conveys
the electric current." Electrical current 1) operates the
telephone and 2) your voice varies that current to communicate.
With those two important points established, let's look at telephone
history.
Click here for a very large image demonstrating
how a telephone works
The telephone is an electrical
instrument. Speaking into the handset's transmitter or microphone
makes its diaphragm vibrate. This varies the electric current,
causing the receiver's diaphragm to vibrate. This duplicates
the original sound. Take
a look at this image to make this point much more clear.
Modern
telephones don't use carbon in their handsets. They use electret
microphones for the transmitter and piezoelectric transducers
for receivers but the principle described in the image linked
above is the same. Sound waves picked up by an electret microphone
causes "a thin, metal-coated plastic diaphragm to vibrate,
producing variations in an electric field across a tiny air gap
between the diaphragm and an electrode."[Britannica
definition] A piezoelectric transducer
uses material which converts the mechanical stress of a sound
wave upon it into a varying electrical signal.
Telephone history begins at the start of human history. Man
has always wanted to communicate from afar. People have used
smoke signals, mirrors, jungle drums, carrier pigeons and semaphores
to get a message from one point to another. But a phone was something
new. Some say Francis Bacon predicted the telephone in 1627,
however, his book New Utopia only described a long speaking
tube. A real telephone could not be invented until the electrical
age began. And even then it didn't seem desirable. The electrical
principles needed to build a telephone were known in 1831 but
it wasn't until 1854 that Bourseul suggested transmitting speech
electrically. And it wasn't until 22 years later in 1876 that
the idea became a reality. But before then, a telephone might
have been impossible to form in one's consciousness.
While Da Vinci predicted flight and Jules Verne envisioned
space travel, people did not lie awake through the centuries
dreaming of making a call. How could they? With little knowledge
of electricity, let alone the idea that it could carry a conversation,
how could people dream of a telephonic future? Who in the fifteenth
century might have imagined a pay phone on the street corner
or a fax machine on their desk? You didn't have then, an easily
visualized goal among people like powered flight, resulting in
one inventor after another working through the years to realize
a common goal. Telephone development instead was a series of
often disconnected events, mostly electrical, some accidental,
that made the telephone possible. I'll cover just a few.
There are many ways to communicate
over long distances. I have reproduced a nice color diagram which
shows the Roman alphabet, the international flag code, Morse
Code, and semaphore signaling. Click
here to view
II.
Early Telephone Development
For more information on Leyden
jars, including photographs and instructions on how to build
them, go this page at the Static Generator site:
http://www.alaska.net/~natnkell/leyden.htm
A static electricity web page is here:
http://www.sciencemadesimple.com/static.html
In 1729 English chemist Stephen Gray transmitted electricity
over a wire. He sent charges nearly 300 feet over brass wire
and moistened thread. An electrostatic generator powered his
experiments, one charge at a time. A few years later, Dutchman
Pieter van Musschenbroek and German Ewald Georg von Kleist in
1746 independently developed the Leyden jar, a sort of battery
or condenser for storing static electricity. Named for its Holland
city of invention, the jar was a glass bottle lined inside and
out with tin or lead. The glass sandwiched between the metal
sheets stored electricity; a strong charge could be kept for
a few days and transported. Over the years these jars were used
in countless experiments, lectures, and demonstrations.
In 1753 an anonymous writer, possibly physician Charles Morrison,
suggested in The Scot's Magazine that electricity might
transmit messages. He thought up a scheme using separate wires
to represent each letter. An electrostatic generator, he posited,
could electrify each line in turn, attracting a bit of paper
by static charge on the other end. By noting which
paper letters were attracted one might spell out a message. Needing
wires by the dozen, signals got transmitted a mile or two. People
labored with telegraphs like this for many decades. Experiments
continued slowly until 1800. Many inventors worked alone, misunderstood
earlier discoveries, or spent time producing results already
achieved. Poor equipment didn't help either.
Balky electrostatic generators produced static electricity
by friction, often by spinning leather against glass. And while
static electricity could make hair stand on end or throw sparks,
it couldn't provide the energy to do truly useful things. Inventors
and industry needed a reliable and continuous current.
In 1800 Alessandro Volta produced the first battery. A major
development, Volta's battery provided sustained low powered electric
current at high cost. Chemically based, as all batteries are,
the battery improved quickly and became the electrical source
for further experimenting. But while batteries got more reliable,
they still couldn't produce the power needed to work machinery,
light cities, or provide heat. And although batteries would work
telegraph and telephone systems, and still do, transmitting speech
required understanding two related elements, namely, electricity
and magnetism.
In 1820 Danish physicist Christian
Oersted discovered electromagnetism, the critical idea needed
to develop electrical power and to communicate. In a famous experiment
at his University of Copenhagen classroom, Oersted pushed a compass
under a live electric wire. This caused its needle to turn from
pointing north, as if acted on by a larger magnet. Oersted discovered
that an electric current creates a magnetic field. But could
a magnetic field create electricity? If so, a new source of power
beckoned. And the principle of electromagnetism, if fully understood
and applied, promised a new era of communication
In 1821 Michael Faraday reversed Oersted's experiment and
in so doing discovered induction.
He got a weak current to flow in a wire revolving around a permanent
magnet. In other words, a magnetic field caused or induced an
electric current to flow in a nearby wire. In so doing, Faraday
had built the world's first electric generator. Mechanical energy
could now be converted to electrical energy. Is that clear? This
is a very important point.
Faraday worked through different electrical problems in the
next ten years, eventually publishing his results on induction
in 1831. By that year many people were producing electrical dynamos.
But electromagnetism still needed understanding. Someone had
to show how to use it for communicating.
<http://www.eb.com:180/cgi-bin/g?DocF=macro/5006/18/5.html>
[Accessed 11 February 1999] 9 (back
to text)
"Piezoelectricity was first observed in 1880 when Pierre
and Jacques Curie put a weight on a quartz crystal and detected
a proportional electric charge on its surface. A year later the
converse effect was demonstrated -- that is when a voltage is
applied to a crystal, a displacement occurs which is proportional
to the voltage."
"Reversing the polarity of the voltages reverses the
direction of displacement. The term piezoelectricity is derived
from the Greek word piezein meaning to press. Hence, a
piezoelectric crystal is one capable of producing electricity
when subjected to pressure."
