17561 Messages Through Ages

8/6/2019 17561 Messages Through Ages

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Messages through

Ages

Breathing, drinking and eating is not all that is necessary to live; we

need to know and tell as well. We need to tell people around when we

are in danger or pain. When we hear somebody shouting or crying we

know she/he needs help. We talk to people around; see or show; read

or write; hear or speak; send or receive letters, almost everyday. It is

all to tell or to know. Without them we would be extremely lonely.

Today, we have paper and pen; books, encyclopedias, magazines,

newspapers and public libraries; post offices; transistor radio,

television sets, portable sound or video recorders; telephones, cell-

phones; Personal computers, Internet .. the list can be very long. But

we did not have them always. Some of them came only in the last

decade, some during the last century, some several hundred or

thousand years ago. Who made these facilities for the first time, when

and how, can be an interesting story to tell and know. This story is

made up of many stories about inventions and discoveries interwoven

into one another.

Let us know this story.

The Language

We all know how to cry or smile from the moment of our birth. A

newborn child cries whenever it needs feed or is uncomfortable. As

soon as it feels the reassuring pat of its mother when placed closed to

Messages through Ages a manuscript submitted to CBT -48

as an entry for book writing competition.1


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her breast it stops crying. Indeed, besides gesturing like smiling and

nodding, it is easiest to tell or to know through sounds. To tell and

know is to communicate; through sounds it is oral/audio

communication. It developed with the discovery of language, a shared

code of sounds. A language is something spoken or written. It is an

organized set of a number of sounds. These sounds convey a meaning

from the mind of the speaker to the mind of the hearer, and thus

connect them to each other.

It must have taken the primitive man thousands of years to invent

writing. (Some languages have never been written; say some of the

African languages.) Civilizations across the globe developed their own

languages. The more efficient was the language, faster did the

civilization develop. This was the reason why the Egyptian civilization,

the Sumerian civilization (ancestors of Iraqis), the Indus valley

civilization and the Chinese civilization are recognized to be the most

developed ancient civilizations. They saw the dawn of graphic

communication, which includes communication through drawings and

letters, first of all. We can claim so because some samples from these

civilizations, dating as far back as 5500 years ago have survived. One

of the earliest mode of graphic communication we know is: Hieroglyphs

picture writing used by Ancient Egyptians. Hieroglyphs were little

pictures representing words. They would denote the word bird by a

little picture of a bird but clearly without further development this

system of writing could not represent many words. The way round this

problem adopted by the ancient Egyptians was to use the spoken

sounds of words. For example, the English sentence I hear a barking

dog might have been represented by the following sequence of

pictures:

an eye, an ear, bark of tree + head with crown, a dog.




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The Egyptians had a base 10 system of

hieroglyphs for numerals, that is, they had

separate symbols for one unit, one ten,

one hundred, one thousand, one ten

thousand, one hundred thousand, and one

million.

Similarly, in Mexico and Guatemala, Mayan Glyphs (drawings

representing words) were used and Sumerians; Babylonians; Assyrians;

Hittite and Persians used Cuneiformwedge shaped characters.

In ancient China a character denoted an idea

or complete word. The character had a

meaning

but gave no clue to its

pronunciation. A sample of some

characters from a writing dated

around VII-III centuries BC is illustrated here. The first character

represents a chicken, the second a sheep, third a bat, followed by the

tortoise and the fish.

The oldest script that was adopted to write in ancient India is perhaps

Indus script; it refers to short strings of symbols associated with the

Harappan civilization that is still undeciphered. A later widely used

script is known as Brahmi.

Sanskrit is another

language developed by

the Indus Valley

civilization (Ancient India).

Its oldest known form is




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Vedic or Vedic Sanskrit, so-called because it was the language of the

Vedas. The Vedas probably date back to about 1500 B.C. or earlier,

much before Brahmi was developed. The Brahmi alphabet is the

ancestor of most of the Indian scripts including Sanskrit.

Most of the common systems for writing in the world were based (and

are still) on symbols determined by sounds rather than words. As we

know, a letter of an alphabet can be a vowel or a consonant. In an

alphabet, each vowel represents a single sound and each consonant

represents a combination of sounds. With such systems, far fewer

symbols are required. The earliest alphabet was invented in Ugarit --

the modern country of Syria, during the 2nd Millennium BC. It was

derived from a previous Cuneiform writing system. The original

alphabet was invented by Semitic peoples (people who live primarily in

areas of the Middle East and northern Africa and speak Semitic

languages such as Arabic and Hebrew) and only contained consonants.

To make it easier to remember the symbols, they were taken from

words beginning with the sound represented.

Both oral and graphic communication could be deployed across

distances and time. While a written message could be carried across a

distance and survive the vagaries of time, vocal communication was

far more economical. Some primitive civilizations, like the Africans had

discovered communication through drums. Sounds of drums could be

heard farther away, and the same sounds could be relayed still further.

But, sending a written message had its own advantages; no one could

eavesdrop. A postal service was first used in China in 900 B.C.

Ancient languages crossed borders along with travelers and migrants.

Thus many modern languages have common ancestors and therefore

have some similarities. Today, while there are borders across which

different languages are used, for many languages there are no borders.

For example, the languages used in science. The language of




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chemistry, physics and mathematics are almost universal. Languages

have been developed to talk to electronic devices, the computers.

They are used to tell a computer, how a problem can be solved or how

it should respond. These languages known as computer languages are

far more accurate and precise then any other language our ancestors

had ever known. Languages have also been developed to enable

people who cannot speak, listen or see.

Imprint

For graphic communication, something to write upon/with is necessary.

Some samples of the ancient writings, that have survived, are in the

form of clay tablets or papyrus (something to write upon invented by

Egyptians, made from the stalks of a plant called papyrus. Sheets were

made by cutting the stem of the plant into strips. These strips were

soaked in several baths to remove some of the sugar and starches.

These strips were then laid in rows horizontally and vertically. Then it

was beaten together, activating the plant's natural starches and

forming a glue that bound the sheet together. Separate sheets were

glued together to form a roll.), while others are engravings on rocks,

bones or wood. As graphic communication advanced beyond chiseling

pictures into stone or wedging pictographs into wet clay, the Chinese

invented and perfected Indian Ink. Originally designed for blacking

the surfaces of raised stone-carved hieroglyphics, this ink was a

mixture of soot from pine smoke and lamp oil mixed with the gelatin of

donkey skin and musk. Other cultures also developed inks using thenatural dyes and colors derived from berries, plants and minerals. In

early writings, different colored inks had ritual meaning attached to

each color.




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The other necessity for writing is an instrument to write with. The

Greeks introduced the earliest instrument of writing that approached

the pen. They employed a writing stylus, made of metal, bone or ivory,

to place marks upon wax-coated tablets. The tablets made in hinged

pairs, closed to protect the scribes notes. Thus the first examples of

handwriting (purely text messages made by hand) originated in

Greece. A scholar from Greece, Cadmus invented the written letter -

text messages on paper sent from one individual to another.

Invention of Paper

Nobody knew paper 1900 years ago! A Chinese, Tsai Lun, invented

paper in 105 AD. He experimented with a wide variety of materialsand refined the process of macerating the plants fibers until each

filament was completely separate. The individual fibers were mixed

with water in a large vat and then a screen was submerged in the vat

and lifted up through the water, catching the fibers on its surface.

When dried, this thin layer of intertwined fiber became paper. Tsai

Luns thin, yet flexible and strong paper with its fine, smooth surface

was known as Tsai Ko-Shi , meaning: Distinguished Tsais Paperand he became the patron saint of papermaking. It took about a

hundred years for the use of paper to spread across central Asia.

Books followed soon after. To produce books required printing. The

very first books were printed in China, by stamping of seals

(something like rubber stamps used nowadays) on paper.

The utility of books prompted people to improve the technique of

making paper. The pioneers of this venture were mostly the Asians. Japanese discovered a method to make paper from waste paper.

Egyptians used cloth rags to make paper. This knowledge gradually

made its way to the western countries through the Muslim world - to




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Baghdad, Damascus and Cairo and ultimately to Europe in the 12th

century.

The Europeans quickly grasped the merits of printing on paper. They

improvised methods for making paper on a large scale. The earliestpaper in Europe was made from recycled cotton and linen. This was

an impetus for the trade of old rags. When this source became

insufficient curious attempts were made to source new materials - the

most macabre of which was the recycling of Egyptian mummies to

create wrapping paper! They also experimented with fibers such as

straw, cabbage, wasp-nests and finally wood. Ultimately this quest

ended when inexpensive and replaceable materials for papermaking

the long soft fibers of softwoods such as spruce, were discovered. A

paper mill, that is an industry to produce paper on a large scale, was

established for the first time in England in the year 1495.

The instrument used for writing that dominated for the longest period

in history (over one-thousand years) was the quill pen. Introduced

around 700 A.D., the quill was a pen

made from a bird feather. Thestrongest quills were those taken

from living birds in the spring from

the five outer left wing feathers. The

left wing was favored because the

feathers curved outward and away

when used by a right-handed writer. Goose feathers were most

common; swan feathers were of a premium grade being scarcer and

more expensive. For making fine lines, crow feathers were the best,

followed by the feathers of the eagle, owl, hawk and turkey.

Pencil was most likely invented in England, after some shepherds in

Borrowdale found small pieces of a charred oak tree that had fallen




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during a storm, useful for marking sheep, sometime in 1564. Soon

thereafter small pieces of this material were encased in wood to

produce a sturdy and clean writing instrument that needed no ink.

Many people have wondered why the core of a pencil is called lead.

The answer perhaps lies in the fact that Greeks and Romans used small

disc shaped pieces of lead to write, way back in 20 B.C. Thats why

material discovered by shepherds was initially known as plumbago

(imitation Lead), until a Swedish scientist, W. Scheele, found it to be a

form of carbon and gave it the name graphite (from the Greek word

Graphis for writing). Fountain pens and the ballpoint pens came

much later, the earliest surviving fountain pens date to the early 18th

(or possibly later 17th) century; they are made of metal, or cut quills

used as nibs. From the beginning of the 19th century, the number of

fountain pen designs patented and produced began to multiply. Three

major advances paved the way for the fountain pens widespread

acceptance: the invention of hard rubber (a naturally-derived plastic,

resistant to chemicals, easily machined, and relatively cheap); the

availability of iridium-tipped gold nibs; and improved inks, not laden

with clogging sediment. But, all these three factors fell into placelater, sometime around 1870 - 1880.

To produce many copies of a document in a short time, a machine to

print is necessary. Printing has a long history. Chinese printers were the

first to structure printing in a way that hinted at mass-production in the

8th century. They used wooden blocks with characters carved into

them, which were then inked and stamped on paper. Extending the

Chinese monopoly on printing, in the 11th century Pi Sheng created a

primitive form of moveable type (made of wood), which allowed for the

letters to be rearranged. In a neighboring country Korea, moveable

metal type was tried in the early 15th century but it was not very

successful due to the large number of characters in Korean script. In




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Europe printing developed a bit later. Till the beginning of the 15th

century, they followed the method introduced by Chinese -- block

printing.

As the methods for casting metals became known, the invention of amachine to print became possible. An innovator in Germany, Johann

Gutenberg spent over ten-years developing the western-style

moveable type. He then developed a method using lead and tin alloys

to mold moving type for individual letters of the

Roman script. He also invented a machine, the

printing press that was based on the design of

presses used by farmers to make olive oil. The

first printing press used a heavy screw to force a

printing block against the paper below and the ink

used was a mixture of turpentine, lampblack and

linseed oil. Invented by 1450 such a printing press

made the mass publication and circulation of literature easy and

economical. In the later models, as machines became more popular,

inking was carried out by rollers. These rollers would pass over the face

of the type and move out of the way onto a separate ink-bed to pick up

a fresh film of ink. A sheet of paper was slid against a hinged plate,

which was rapidly pressed onto the type and then swung back,

allowing it to be removed and the next sheet inserted in its place.

The invention of the printing press with loose type cleared the way for

the gradual proliferation of the printed word in the 15th century. An

obvious second step after the invention of the printing press was a

machine that could make hand written documents look like the printed

documentsa typewriter.




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The invention of a practical typewriter had to wait till 1867 although all

the skills needed to make one were available in

the eighteenth century. One may wonder why

wasnt a typewriter built earlier. After all a

clock, has a mechanism that is far more

complex than that of a typewriter and clocks

were common in Europe by that time. The

answer is simple enough. There was no need

for typewriters in a world where cheap labor

was abundant and where machines were

expensive. So, even though an Englishman,

Henry Mill, had got a patent for typewriter in

1714, it was not until nineteenth century, when

industrial production was automated and

boomed, that a practical typewriter was

produced. A young engineer, Christopher Latham Sholes, designed the

first practical typewriter in the United States of Americaan under

populated country, where labor was scarce, in 1867. They were

marketed in 1873. The action of the type bars in the early typewriterswas very sluggish, and tended to jam frequently. To fix this problem,

Sholes found out a list of the most common letters used in English, and

rearranged his keyboard from an alphabetic arrangement to one in

which the most common pairs of letters were spread fairly far apart on

the keyboard. The typewriter soon took its rightful place among the

great inventions for communication.

Patent

A patent is the grant of a legal property right to the inventor, issued

by the government of a nation. It gives an inventor the right for a

limited period to stop others from making, using or selling products

based on the invention without obtaining the permission of the




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inventor. It is a deal between an inventor and the state that allows

the inventor a short-term monopoly in return for allowing the

invention to be made public.

Now, we use ballpoint pens that can be as cheap as a 50p coin. Wemay have a photocopying machine available at our street corner.

Newspapers are published by printing presses that can print several

thousand pages every second. Some of them are printed in remote

locations simultaneously.

Instant Messaging

Till about 1780 instant remote communication was difficult. While an

audio message could be sent at the speed of sound (about 300m/s)

with the help of drums, there was no surety that it would reach its

destination uncorrupted. A written message could be sent from one

city to another only as fast as a horse rider could travel, because it

could be sent only through couriers. Often it would take weeks before it

reached its destination. After the invention of the steam engine in 1698

and the establishment of railways, travel from one place to another

became faster. Messages could then be received far more quickly. But,

not from places farther away from a railway stations or a river. Other

solutions were called for. One such solution was the system of

semaphores.

The system of semaphores was made up of a series of towers that had

movable arms on which flags could be mounted. Messages were coded

using a set of flags. People known as spotters were stationed on each

such tower, they used a telescope to see the nearest semaphore and

relay the message further by putting up similar flags on their tower.

The first semaphore line was established in France between Paris and

Lille in 1792. It was used to carry dispatches for a war between France

and Austria. A message to Lille would pass 193 km through 15




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semaphores in only nine minutes. The speed of the line varied with the

weather. Many governments of several nations saw merit in this

system and the American Government was keen to adopt it for

nationwide communication in 1837. It was this opportunity that led a

young American inventor Samuel Fineley Breese Morse to invent the

Telegraph.

Telegraph is one of the most significant inventions in the history of

communication. Long distance, instantaneous communication was not

always possible prior to its establishment. Its implementation

revolutionized many facets of human life. News could travel much

faster, and people could receive messages quickly. It was the first

communication system invented after the discovery of electricity and

the invention of electromagnets.

The Story of Electricity and Magnetism

A Greek philosopher Thales of Miletus, who lived about 600 BC, is

said to have discovered that amber acquires a power to attract light

objects when rubbed. Another Greek philosopher, Theophrastus, in a

treatise written about three centuries later, told that some other

substances also possess this power. Similarly, ancient Greeks as well

as Chinese knew magnets. But, it was not until AD 1600, when an

English physician William Gilbert studied both of them in detail and

his observations were available in printed form, that the facts about

electricity and magnetism became widely known. Gilbert was the first

person to apply the term electric (Greek elektron, amber) to the

force that such substances exert after rubbing. He also distinguishedbetween magnetic and electric action.

The first machine for producing an electric charge was invented in

1672 by a German scientist Otto von Guericke. It consisted of a sulfur

sphere turned by a crank on which a charge was induced when the




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hand was held against it. The French scientist Charles Francois de

Cisternay Du Fay was the first to discover that there are two different

types of electric charge: positive and negative. The earliest device to

store electric charge, the Leyden jar, was invented in 1745 at the

University of Leiden in the Netherlands. It consisted of a glass bottle

with separate coatings of tinfoil on the inside and outside. One

sensed a violent shock by touching both coatings of the foil

simultaneously.

Benjamin Franklin, an American scientist, spent much time to study

electricity. Through his famous kite experiment he discovered that the

atmospheric electricity that causes the phenomena of lightning and

thunder is identical with the electrostatic charge on a Leyden jar.

Franklin suggested that electricity is a fluid existing in all matter,

and that its effects can be explained by excesses and shortages of

this fluid.

Alessandro Volta, an Italian scientist invented the first

device capable of producing an electric current

(electricity), a battery. He found that if pieces of twodifferent metals were separated with a cardboard disk

soaked in brine (salt solution), an electric current flows through the

wires connected to these metal pieces. In 1800, he announced a new

electrical device,the Voltaic Pile. This device was made of alternating

disks of zinc and copper with each pair separated by brine soaked

cloth. This was the first battery.

In 1819, a Danish scientist Hans Christian Oersted discovered, thatwhen an electric current is passed through a coil of metal wire it

behaved like a magnet. Later in 1825, a British electrician, William

Sturgeon invented the electromagnet. The first electromagnet was a

horseshoe-shaped piece of iron that was wrapped with a loosely




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wound coil of several turns. When a current was passed through the

coil; the electromagnet became magnetized and when the current

was stopped the coil was de-magnetized.

The invention of the printing press, the postal service and the librarieshad made it possible for people across countries to know the results of

experiments conducted by scientists in different countries many years

ago. So in 1832, when young Samuel Morse set himself the task to

invent an efficient and fast messaging system, he knew about all the

discoveries and inventions related to electricity. After all, he was well

educated in science. He also knew that electric current travels at a

phenomenal speed. Although he did not understand electromagnetsthat well, he could find scientists who helped him in this regard.

Morse also came to know that another American inventor Joseph Henry

had sent a message via a wire in 1830. The experiment involved

sending an electric current over a one-mile long wire, where it hit an

electromagnet, and subsequently caused a bell to ring. Samuel Morse

took Henrys idea and expanded upon it. He began sending electric

currents along lines to an electromagnet in 1835 but instead of strikinga bell his device would move a marker that produced written codes on

paper. This led to the development of Morse code, the system of

dashes and dots by

which telegraph

signals were sent and

decoded. In 1838, the

US Government

funded a telegraph

line between

Baltimore, and

Washington two

important cities of




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USA. This led to the widespread recognition of telegraph services.

After sometime it was found that experienced people could decode the

sounds produced by a new kind of telegraph machines called

sounders. This gave rise to the vocation of telegraph operators.

These telegraph operators had the status something like that of

computer programmers today. They could write down messages by

listening to the pattern of clicks. Experienced operators could even

sleep through the night shift and would wake up by the clicks of a

message from their desired address.

Soon telegraph wires were visible across USA, mostly following railway

lines. This method for instantaneous remote communication proved

useful for many industries including the railways. Telegraph stations

were set up. Poles were erected along the railway tracks, for the

telegraph wires. The managers of railways used telegraph to regulate

the movement of trains. Messages about current events and business

transactions were also sent via the telegraph. It was useful for the

army too. By the 1850s, engineers had begun to lay underwater

telegraph lines for short distances. By the late 19th century, many

cities across the world were crisscrossed by a maze of electric wires.

Originally, telegrams were sent through two copper wires connected to

the two terminals of a battery. However, it was later discovered that

the second wire could be eliminated because the earth can also serve

as an electrical conductor. An underwater wire was laid across the

Atlantic Ocean to carry messages through telegraph in 1866. In 1874

the famous American inventor Thomas Alva Edison had found a way to

send four telegraph messages at once.

Till about fifty years ago the landline telegraph consisted of three

parts: a battery, a key, and an electromagnet all connected by wire.

The battery supplied the electric current, the key used to complete or

break the circuit and the electromagnet used to pull on a piece of




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metal when electricity passes through it. Later the key was replaced by

a keypad of a teleprinter, a kind of typewriter. Through the teleprinter

messages could be typed in plain English.

Today we do not see telegraph anywhere but it was indeed theinformation superhighway of the yesteryears.

Recording Images

We see a new scene almost every other moment we are awake. It may

be people around us or the places and machines. Often we want to tell

others what we have seen, but words seldom suffice. There is an old

saying A picture says more than a thousand words. Although people

had learnt to draw and paint pictures from time immemorial, the need

for a device that could accurately record the picture of a scene, a

camera, was always felt. The earliest form of a camera invented is

often called Camera Obscura. A Chinese philosopher Mo-Ti (5th

century BC) was perhaps the first person to mention this type of

device. He formally recorded the creation of an inverted image formed

by light rays passing through a pinhole into a darkened room. He called

this darkened room a collecting place or the locked treasure room.

Aristotle (384-322 BC), a famous Greek philosopher, also understood

the optical principle of the camera obscura. He viewed the crescent

shape of a partially eclipsed sun projected on the ground through the

holes in a sieve, and the gaps between leaves of a plane tree.




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The earliest Camera Obscuras were large rooms that were used to

observe a solar eclipse. A convex

lens was used into the aperture in

the 16th century to improve theimage quality; a mirror was added

to reflect the image down onto a

viewing surface. This device was

often used as an aid for drawing for artists. Soon thereafter, in 1807,

another kind of camera known as Camera Lucida was invented. No

darkroom was needed for this kind of camera. The paper was laid flat

on the drawing board, and the artist would look through a lens

containing the prism, so that he could see both the paper and a faint

image of the subject to be drawn. He would then fill in the image.

Obtaining a direct recording of an image that did not require the skills

of an artist was not possible till certain chemical substances that

changed their properties when they are exposed to light became

known. A German scientist discovered in 1727 that if he mixes three

chemicals: chalk, nitric acid, and silver in a flask, the side of the flaskfacing sunlight gets darkened. In 1800, a scientist from England,

Thomas Wedgwood, made the first sun pictures by placing opaque

objects on leather treated with a chemical called silver nitrate.

However, these pictures survived only under candles light, under any

stronger source of light they detoriated very fast. It was not until 1826

when a French scientist Nicphore Nipce, combined the camera

obscura with photosensitive paper that it was possible to obtain a

permanent image. Soon thereafter, in 1834, another English scientist,

Henry Fox Talbot, used paper impregnated with silver nitrate or silver

chloride. When exposed in a camera, this paper turned black where

light struck it, creating a negative image of the subject. This was made

permanent by fixing with hypo. The images so obtained were of course




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only black and white. (The story of development of photography is very

aptly detailed on the website

http://www.scphoto.com/html/history.html.)

These early development led to many other discoveries and inventionsthat made it possible for newspapers to carry photographs by 1880.

Way back in 1900 one could purchase a camera and shoot pictures

using photography films produced by the company Eastman Kodak.

Cameras to record a sequence of pictures that can be projected with

the help of projectors-- known as the Magic Lantern, were invented

much later. It was the invention of this kind of camera that led to

cinema.

Through wires

By the later part of the nineteenth century, wires for sending messages

were a common sight in England and USA. The basic necessity for

telegraph was electric power. In the beginning telegraph messages

were sent using an electric battery but soon other more economical

sources were available. For example, in 1831 Michael Faraday, a British

scientist discovered the electromagnetic induction. This is a method for

producing a steady electric current. Faraday attached two wires

through a sliding contact to a copper disc. By rotating the disc between

the poles of a horseshoe magnet he obtained a continuous direct

current. This was the first electric generator, it led to the establishment

of the first electric power station in 1888.

The success of telegraph had started igniting young minds in Europe

and America. Many people thought about the possibility of talking

through wires, but no body knew how voice could be converted into

electric current and vice versa. One such young man was Alexander

Graham Bell. His father was a speech teacher who had worked out a

system called visible speech. This system used symbols to represent




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all of the sounds that people make while speaking. He hoped to use

this sound alphabet for teaching the art of speaking to deaf people.

Deaf people have trouble speaking clearly because they cannot hear

what they are saying. Young Alexander Bell was fascinated by his

fathers work. When he was sixteen years old his father challenged him

to build a machine that could make speech sounds. He therefore

studied the larynx, the voice-producing organ, of a lamb. Soon he

developed a voice box that made different sounds using levers. He also

studied how the mouth changes shape while making vowel sounds.

From books he came to know that a learned German scientist, Herman

von Helmholz, had used electrically operated tuning forks to reproduce

certain sounds of human speech.

Graham Bell started his efforts in the direction of the invention of

telephone by attempting to develop a harmonic telegraph, a device

that would allow several telegraph operators to send messages on the

same wire at the same time. Thus he developed an idea for the

telephone. By October 1874, Bells research had progressed to the

extent that he could inform his future father-in-law, Gardiner Greene

Hubbard, about the possibility of a multiple telegraph. Hubbard

resented the absolute control on telegraph services exerted by the

Western Union Telegraph Company in USA at that time. He instantly

saw in the Bells efforts a potential for breaking such a monopoly, so

he gave Bell the financial backing he needed. Bell proceeded with his

work on the multiple telegraph. But he did not reveal to Hubbard that

he and Thomas Watson, a young electrician whose services he had

enlisted, were also exploring an idea that had occurred to him that

summer. The idea was to develop a device that would transmit speech

electrically. They were working on a device that used steel reeds that

could be set in vibration by electromagnets. One day Watson tightened

an adjustment screw of his device a little too much. This prevented the




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reed from vibrating, so he plucked the reed to try to set it in motion

again. Bell sitting in another room next to his instruments heard a

sound coming from the reeds in the device near him. He rushed to

Watson to find how it happened. What excited him the most was the

fact the sound was not produced by an on and off electric current as

was the case with electric telegraph it was a continuous sound. Soon

thereafter Bell experimented with vibrating membranes instead of

reeds. He was prompted to do so by his knowledge of the human ear.

Within a few weeks he was successful in transmitting the sounds of

human voice through system that was composed of a microphone and

a speaker. The microphone was like a funnel. One end open the other

end pointing to a membrane connected to a rotor that had to follow the

vibrations of the membrane. This vibrating rotor was connected to a

coil to induce an electric current that could reproduce the voice sent

into the funnel. Bells microphone changed sound waves into an

electric current whose intensity changed quickly. The electric current

can travel much faster and it is easier to transmit it across long

distances than sound.

Graham Bell was not the only person who was trying on such an idea.Another American inventor Elisha

Gray was working on similar lines. In

fact he also smelt success just at

the same time. But on February

14 1876 when Bells father in law

filed an application for the

preliminary patent of Bells

invention, Elisha Gray was just a

few hours too late. Nevertheless

Bell had to face many problems

similar to the ones faced by many other inventors at that time. Nobody

was initially interested in his invention. When he offered his patent for




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100,000 American Dollars, the response was What shall we do with a

toy like that? This occurred in 1877. The telephone invented by

Graham Bell was not immediately accepted for conversation, it was

more commonly used to send and listen to music. But after some

improvements it became popular for conversations. The first regular

telephone line from Boston to Somerville, two towns in USA, was

completed in 1879. One can gauge the immediate success of

telephones by the fact that by the end of 1880 there were 47,900

telephones in the United States.

Early telephones were leased in pairs to subscribers. The subscriber

was required to put up his own line to connect with another. The facility

that one subscriber of the telephone service can connect to any other

subscriber was possible only after many other inventions. For example,

an American, Almon B. Strowger, invented a switch that could connect

one line to any of 100 lines by using relays and sliders (kind of electric

switches) in 1889. This switch became known as The Strowger

Switch, it was used in some telephone offices well over 100 years

later. Another famous American inventor, Thomas Alva Edison invented

the carbon microphone that helped the transformation of speech into

electric current much more effectively. The carbon-based microphone

Edison invented was used in telephones till early 1990s.

Today, there are telephones almost everywhere. The total number of

telephone subscribers in the world exceeds one billion. One can even

send the picture of a document through telephone using a special kind

of instrument, the facsimile (fax) machine. The instrument used to

converse need not always be connected through wires; it can be

without them also.




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Without wires

Telephone invented by Alexander Graham Bell had its limitations. It

could only be used to communicate with persons located at places

connected through telephone wires. A telephonic conversationbetween two persons one at sea and other on a mountain was

impossible. Communication without wires that is wireless

communication became possible only after the discovery of

electromagnetic waves.

The discovery of electromagnetic waves

In 1831, a British scientist Michael Faraday discovered that changing

electric current in a coil of wire can induce a current in a nearby coil.

The current induced in the second coil is proportional to its number of

turns. James Clerk Maxwell, a compatriot of Faraday, was a

theoretician. A theoretician is a scientist who does not work with

instruments or devices rather he dabbles with mathematical

formulations of observations. In 1865, as a result of his studies, he

discovered the mechanism of interaction between electricity and

magnetism. He suggested that a change in electric current can start

a train of waves, the electromagnetic waves, that radiate into space

just like light waves. According to him, the only difference between a

light wave and an electromagnetic wave is a characteristic of waves

the wavelength. Not all scientists accepted Maxwells ideas; after

all there was no proof of the existence of electromagnetic waves. The

Berlin Academy of Science offered a prize to anyone who could prove

that electromagnetic waves exist. In 1879, Heinrich Rudolf Hertz, aGerman scientist took the challenge in 1886.

Hertz knew the work of Faraday. He devised a simple experimental

setup made up of two devices. The first device had two coils placed

near one other. He passed electric current from a battery into the first




23/38

wire coil. The second coil had many more turns than the first coil. As

per the discovery of Faraday the voltage developed in the second coil

was much higher than that of the battery. This current was led to a

pair of capacitors. (A capacitor is a pair of metal plates that can

accumlate electricity until they can hold no more.) As soon as the

capacitors were charged to their capacity they discharged by sending

an electric spark between two small metallic balls. The second device

had similar balls connected to a wire that was bent into circle and it

was placed at a distance from the first device. He demonstrated that

whenever an electric spark was generated in the first device a spark

can be observed in the second device also, even though the two were

not connected through any wires. The only way these two devices

could communicate with one another was through electromagnetic

waves. This proved Maxwells ideas.

The invention of a practical communication device, using

electromagnetic waves, came a bit later. Not before it was discovered

that out of various electromagnetic waves, only those having

wavelength more than a meter could be used for remote wireless

communication. For example, light waves could not be used for

communication because most common objects obstruct them. They

cannot pass through a wall of a building. Electromagnetic waves that

can go across walls and hence can be used for long distance

communication are called radio waves. They can be transmitted

without wires or through wires, just like electricity. It was also found

that radio waves having nearly equal wavelength interfere with one

another, if received simultaneously at a particular location. Therefore

radio waves of a particular wavelength can be used to communicate to

people at a particular location only if nobody else is transmitting radio

waves of the same wavelength. Many inventors in different countries

tried simultaneously to invent a communication device using radio




24/38

waves. For example, in 1893 a scientist born in Hungary, Nikola Tesla,

made the first public demonstration of such a system. He described

and demonstrated in detail the principles of radio communication. The

apparatus that he used contained almost all the elements that were

used later. In 1894, an Indian scientist, Jagdish Chandra Basu, also

demonstrated publicly the use of electromagnetic waves in Kolkata. He

was not interested in patenting his work, so his work is not recognized

internationally. In the same year a British physicist, Sir Oliver Lodge,

demonstrated the reception of Morse code signalling using radio waves

with the help of a detecting device -- a coherer. This coherer was a

tube filled with iron filings. It was invented by an Italian, Temistocle

Calzecchi-Onesti, in 1884 to drain off electricity during lightening.

Edouard Branly of France and Alexander Popov of Russia later produced

improved versions of the coherer. Many people claim that Popov was

the first person to develop a practical communication system.

The inventor who is generally recognized as the inventor of wireless

telegraph is Gugliemo Marconi, an Italian. He began by building an

apparatus similar to the one used by Hertz. He added a telegraph key

to the spark generator, so that he could send signals corresponding to

the dots and dashes of the Morse code. To check whether it was a

practical communication device Marconi moved his appratus outdoors

to try its transmission- reception over long distances. During these

experiments he made a lucky discovery: When one terminal of the

generator and receiver were connected to the ground, communication

was possible across longer distances. He also discovered the need for

antenna (aerials); they transmit signals from the transmitter to space

and from space to the receiver equipment. By 1895, Marconi had

developed a device with which he could send signals across a few

kilometers. Marconi got a patent for his inventions in 1896, the worlds

first patent for radio communication. After patenting his invention


http://en.wikipedia.org/wiki/1896http://en.wikipedia.org/wiki/1896


25/38

Marconi established a company called Marconis Wireless Telegraph

Company in London. In 1898 Marconi successfully transmitted signals

across the English Channel. The most dramatic use of wireless was for

rescuing ships in distress. Several ships were equipped with wireless

telegraphy equipment, they could send or receive distress messages

from ships sailing nearby.

Till the beginning of the twentieth century, wireless communication

was limited to telegraphy. Many people dreamt of wireless telephony at

that time, but the technology to achieve that was not available.

Sound waves are continuous waves, their frequency is much lower

than that of electromagnetic waves. (Frequency is anothercharaceristic of a wave

very closely related to its

wavelength). For wireless

communication a sound

signal has to be converted

into a radio wave. It was

soon found that any

electric signal can be

carried on a radio wave

(modulation of electromagnetic waves). All that was necessary for

wireless communication of sound was an equipment that could

generate electric current having frequency of the radio waves. Several

inventors invented such devices. The most notable amongst them was

Nikola Tesla, who invented the alternating current and Ernst

Alexanderson who built the first alternator that could produce

alternating current having frequency about 50 thousand cycles.

Although the exact time when the human voice was first transmitted

by radio is debateable, it is claimed that speech was first transmitted

across the American continent, from New York City to San Francisco, in




26/38

1915. During the First World War radiotelephony between ground and

aircraft was also tried. The first ship-to-shore two way radio

conversation occurred in 1922. However, a public radiotelephone

service for people at sea was inaugurated in 1929. At that time

telephone contact could be made only with ships within 2000 km of

shore. Today every large ship wherever it may be on the globe can be

contacted using wireless equipment.

The invention of wireless really revolutionized communication when

voices/sounds could be broadcasted from local facilities, called radio

stations and received by anybody who had a radio set. By 1920s

amatuer radio operators in USA could set up their own radio stations

that broadcasted music and news. These programs could be picked up

by any body within a distance of 30-50 km, having a radio,a device

that can be tuned to receive radio waves of a particular frequency.

They could be purchased from the local market or assemled at home.

Soon political leaders, like the president of the country, could deliver

speeches through such equipment.

Broadcast of radio programs became extremely popular after the

invention of vacuum tube amplifiers and superhetrodyne circuits by

Edwin Armstrong and the easy availability of electricity. Today, one can

catch radio programs being transmitted by a nearby radio station using

a low cost pocket sized transistor radio. But that is because of yet

another invention, that of semiconductor diodes and transistors.

The invention of radio gave rise to a spurt for the invention of many

electronic devices and designing of electric circuits involving them,which ultimately led to the invention of television. The story of

invention of television is a bit different from the stories of earlier

inventions. Television was not invented by one inventor, many

inventors from various parts of the world contributed. Therefore, its

story is to be told slightly differently.




27/38

Television, in a way, is an extension of our sense of vision. The process

of televising a visual consists of three steps. Seeing it through a

camera; transmitting it to remote places and finally producing its

image on the screen of a TV. The camera used for television is different

from a photography camera. A photography camera cannot be used for

televising because it does not produce any electrical signals. Finding a

method to convert the image of a visual into a electric current was

indeed the first challenge for the potential inventors of television. The

discovery that led to the invention of television was the discovery of

the chemical element Selenium. A Swedish scientist, Jacob Berzelius,

discovered it in the early nineteenth century. It produces an electric

current when light falls on it and is therefore called a photosensitive

element (photo = light). This discovery led to invention of several

devices that could convert an image into an electric current and

reproduce the image. One such device was invented by a German

engineer, Paul Nipkow, in 1884. This device the Nipkows disk was an

electromechanical device, and hence was not very successful.

For the later developments it was necessary to know what exactly is an

electric current. Nobody knew it till 1897! Electric current became

known to be a flow of electrons after an English scientist, J.J. Thomson,

discovered electrons -- the tiny negatively charged particles in atoms.

The invention of cathode ray tube (CRT) by a German scientist, Karl

Ferdinand Braun, was perhaps crucial for the development of an

electronic television. In 1897, after electrons had been discovered

Braun, like many other scientists of the day was intrigued. Braun

discovered that a stream of electrons emanating from a negatively

charged electrode (cathode) inside a glass tube from which most of the

air had been removeda cathode ray tube (CRT)could be focused to

a point at the end of the tube. If the end of the tube were coated with a

fluorescent material, it would glow wherever the stream of electrons hit




28/38

it. Braun also used a magnet outside the tube, which interacted with

the electrons in the beam to move it back and forth. By moving the

magnet, he could trace patterns on the screen. Braun also used a

magnet outside the tube, which interacted with the electrons in the

beam to move it back and forth. By moving the magnet, he could trace

patterns on the screen.

It was later discovered that an image projected/focussed on the

screen of a CRT can be scanned, read like the text written on a paper,

by moving its beam over each point of the image. Cathode rays were

moved using electromagnets because it was already known that the

strength of an electromagnet can be varied by changing the electriccurrent flowing through it. Scanning an image to produce electric

signal was therefore now possible. Inventors tried coating the screen of

a CRT with selenium and found that the characterstics of electric

current produced depends

on the image focussed on

the screen. The first

electronic device that was

close to the modern TV was

invented by a Russian

inventor, Vladimir Zworykin,

in 1923. He called it

iconoscope, it laid the foundations for early television cameras.

However, the inventor who is most often credited for the invention of

television is John Logie Baird, a Scottish engineer. He achieved thetransmission of simple face shapes in 1924 using Nipkows disc. Baird

demonstrated 'television' publicly in London on March 25, 1925.




29/38

The details of a scene in front of the camera can be transmitted either

through wireless transmitters ( very similar to those used for

broadcasting sounds) or through a cablelike telephone. An image of

the scene can be produced on the screen of a television set by feeding

into its CRT the electrical signal received. The main difference between

the picture tube of a television set and that used in a television camera

is the coating on their screens, while a photoconducting material, say,

selenium, is used for coating the screen of the CRT inside a camera,

chemicals known as

phosphors were (and

are still) used on the

screen of a TV. A

small dot of phosphor

produces a dot of

light when cathode

rays fall on it. This

light lasts only a fraction of second. Such light dots produce a transient

image on the screen. A sequence of such transient images produce a

movie.

The earliest TV broadcasts were limited to live performances in front of

a TV camera. The method/device to record and store TV programs were

not known. This became possible after the invention of Video tape

recorders (VTR). In 1951, the first video tape recorder (VTR) captured

live images from television cameras by saving the information in the

electrical impulses produced onto a magnetic tape. Such tape

recorders were found very useful by organizations engaged in

television broadcast, because a performance can be recorded at one

time and broadcasted later as many times as desired. Portable video

recorders that can be carried to any place were invented much later, in

the last few decades.




30/38

Colour television was invented a bit later. Till about 1956 could only

black and white pictures could be televised. The invention of devices

that could transmit and receive color television programs is credited to

an American company, Radio Corporation of America (RCA). Another

limitation in the television broadcasting was the fact that

electromagnetic waves used for televising can travel only in a straight

line, a few hundred kilometers. A TV programme broadcasted by a TV

station, say in Moscow, cannot be therefore received in Delhi. The

invention of rockets and artificial satellites overcame this limitation.

With satellites placed in the sky signals can be broadcast in the

direction of a satellite that can relay them back to a different location

on the earth. With the invention of rockets, it is now possible to place

satellite at almost any point in the sky. Satellite television is infact

responsible for the cable TV, we are all familiar with.

Networks

Towards the middle of the twentieth century some poeple could read

books, magazines, newspapers printed in distant places; talk across

oceans using telephones; listen or watch public performances through

radio, television or cinema and send messages, letters or pictures

instantaneously through post and telegraph. However, there were

limitations; one was not always free to communicate widely and

independently. Often one had to be at a particular place in order to

converse with another person using a telephone; one had to be at the

mercy of a publisher for wide circulation of a document or of a

Government organization to broadcast a message or story. Only in the

past few decades it has become possible to freely communicate at a




31/38

nominal cost. It is now possible to do so through networks across the

world. The word network is perhaps not very familiar to youngsters.

A network is an interconnected system of things or people. Each thing

or person in a network can communicate with each other. The postal

and telephone services are possible only because of networks.

A devices that is most widely networked is computer. You may be

familiar with one kind of its kind, the personal computer (PC).

The invention of Computer

The story of invention of computer differs from the story of invention

of television. It was invented not by any individual, rather through

large commercial establishments. Several groups of people working

for a large business houses made it possible. The earliest computer

was somewhat like a programmable calculator, it could only make

mathematical calculations. A German inventor, Konrad Zuse, is often

credited with the invention of the first electronic computer is. He

made the world's first electronic, fully programmable digital computer

in 1941, with recycled materials donated by his colleagues in

university. Five years later in 1946, John Mauchly and J Presper Eckert

developed the ENIAC I (Electrical Numerical Integrator And

Calculator) under a project sponsored by the U.S. military. This

computer covered 167 square meters of floor space, weighed 30tons, consumed 160 kilowatts of electrical power. In one second, it

could perform 5,000 additions, 357 multiplications or 38 divisions.

Later computers became significantly smaller. This became possible

due to the invention of a device, the transistor. Three American




32/38

scientists, John Bardeen, William Shockley, and Walter Brattain,

invented transistor while working for the Bell Telephone Laboratories

in U.S.A. (A business house established by Graham Bell -- the inventor

of Telephone). They invented it accidentally while studying the

behavior of crystals of germanium to find something to replace

vacuum tubes as mechanical relays in telecommunications. The

vacuum tubes, used at that time in various devices for

communication, consumed lots of electricity and produced

unneccesary heat. A transistor is made from semi-conductor

materials. A semiconductor material is a kind if material that can

conduct electricity as well as stop its flow (insulator). Chemical

elements germanium and silicon are two examples of semiconductor

materials. A transistor is the first device discovered to be capable of

acting as a transmitter, converting sound waves into waves of

electric current, and a resistor, controlling electric current. No doubt

transistors soon replaced vacuum tubes in the computers. Computers

made up of transistors were more reliable and consumed much less

electricity.

The next step was the integration of many electric devices into a tiny

small crystal of silicon, an integrated circuit (IC). Till 1959, it was

believed that to make a computer more efficient it is necessary to

increase the number of electrical components in it. After the

invention of integrated circuits, hundred of transistors, resistors,

capacitors and connecting wires, could be put into a single

component the chip. A chip is made on a single crystal of a

semiconductor material.The technology for making an IC was

invented by two American engineers Jack Kilby, working for a

company named Texas Instruments and Robert Noyce, the co-founder

of the Fairchild Semiconductor Corporation. Further development of

computer was due to the development of an IC specifically designed




33/38

for computers. In 1971, a microprocessor as an IC, the Intel 4004 was

introduced by a company Intel. Three employees of Intel are said to

be responsible for the invention of this chip: Federico Faggin, Ted

Hoff, and Stan Mazor. In this IC all the parts that made a computer

think (i.e. central processing unit, memory, input and output controls)

are on a single chip.

The person who can perhaps be called the inventor of personal

computers is Douglas Engelbart. He invented or contributed to

several interactive devices and features: the computer mouse,

windows, computer video teleconferencing, email, the Internet and

more. His contributions were complemented by several computer

companies like Apple computers and IBM who introduced Personal

computers in the market. However, the real revolution in PC was the

handiwork of a few computer whizkids: Bill Gates and Steve Jobs who

developed software that is really user friendly.

A computer is not always a desktop PC. There are other kinds of

computers as well. While they may look different there are some

similiarities between all kinds of computers. Inside all of them is asmall device known as a microprocessor (an IC that has billions of

transistors inside it, which help it do its task by stopping or allowing

the electric current through them.) A microprocessor is somewhat like

a brain. All computers have memory to remember information and

instructions (the programs, software). All of them need some software

(education?) to enable them to perform their functions and of course

electricity.

All computers operate digitally, that is signal

used in them are coded digitally. The digits

used are not the same we are all familiar

with, they are binary digits. Any number,

letter of a language, picture or sound or




34/38

letter of a language can be coded in the binary form. The smallest unit

of the memory of a computer is therefore a bit (an acronym for binary

digit). A bit is a device made up of a single transistor, that has only two

possible states, ON (often indicated by the numeral 1) or OFF

(indicated by 0). To store or convey more information, bits are

organized into larger units called bytes -- the commonly used unit of

information in a computer. Each byte contains 8 bits and can represent

only a single character or command. However, to do any thing useful,

lots of bytes are necessary. A brief letter may require just a few

thousand bytes(kilobytes), but to store a postcard size colour

photograph may require several million bytes(megabytes).

One can process, acquire or communicate any kind of information at

an astounding speed using a computer connected to the Internet. The

Internet is a network of many networks of computers. Millions of a

computers known as the server computers located worldwide are

connected to each other through cables (both underground and across

oceans) and satellites, 24 hours a day. These server computers are

capable of communicating with hundreds of other computersconcurrently. One can acquire ones own little corner on the internet

having a unique address at a very low cost and put there any

information one wants to communicate with anybody who is

interested. The Internet has information on almost all topics. Most

people connect their computers at home to the internet through

telephone using a device called modem -- a device that can convert

digital signals into electrical signal commonly used in telephones.Today

one can speak, typewrite, read, draw, print, view pictures, movies, or

enjoy music all on a single device, the PC. One can give oral

commands to a computer or dictate documents that can be written

and printed through a computer. One can also chat with friends or

send/receive messages (email) that may include besides text, pictures




35/38

or music and are delivered within minutes regardless of the distance.

One can find the locations on the Internet where information about a

topic exists, through the facility of search engines (Google, Yahoo.).

Quite often the information available through internet is more than

that available at any library anywhere. It is not always neccesary to

purchase a computer for doing all this. People can often use computers

at commercial outlets, the cyber cafs, that charge a small fee per

hour of usage. Computers are therefore useful not only to a student to

find useful information for a school project, or to send an e-mail to a

friend, they are the ultimate machines for communication.

Another kind of networks that has added to our freedom are the

Automated Teller Machines (ATM) of banks. These machines provide us

the freedom to withdraw money from our bank account, even from

places farther away from branch of the bank where we hold our

account, almost 24 hours a day. Each bank has its own network of

ATMs based on computers. These networks maintains information

about the accounts of each client of a bank in the memory of a central

computer.When a person visits an ATM to withdraw money it can findout how much money is available in his/her account and can dispense

money as well as pass the details of the transaction to the central

computer instantaneously.

Cell phones have provided us the freedom to call/receive telephone

calls from any place: a garden, on a train or in a different city. They are

also based on networks of many radio transmitters/receivers. Each cell

phone company has its own network of this kind. These networks are

cellular akin to the body of a living organism. The area covered by a

cell phone company, a city, a state or a country for its services is

divided into zones that are called its cells. The network of a cellular

company is made up of many such cells. Each cell has a radio




36/38

transmitter/receiver and a computer, located at a place known as its

base station that can broadcast and receive radio waves within a cell.

The invention of the Cell phone

The basic concept of cellular phones began in 1947, when some

engineers in USA looked at crude mobile (car) wireless phones that

were used in USA at that time. The number of the users of such phones

was very small because the number of frequencies available for them

were limited. It was realized that if transmission of radio waves was

limited to a small area, small cells a frequency can be reused in

another remote cell, thus increasing the traffic capacity of mobile

phones substantially. However at that time, the technology to do sowas nonexistent.

In USA, anything to do with wireless communication is decided by a

department known as Federal Communications Commission (FCC).

Since a cell phone is a type of two-way radio, in 1947, an American

company AT&T proposed that the FCC allocate a larger number of

frequencies of electromagnetic waves capable of radio communication

to make mobile telephone service feasible. But FCC declined this

request.

This position was reconsidered in 1968. AT&T and Bell Labs then

proposed the present form of cellular system. In this system many

small, low-powered, broadcast towers, each covering a 'cell' a few

kilometers in radius collectively cover a large area. Each tower uses

only a few of the total frequencies allocated to the system. As the

phones travel across the area, calls are passed from tower to tower.

Dr Martin Cooper, a general manager at an American company

Motorola, is considered the inventor of the portable cellphone

handset. Cooper made the first call on a portable cell phone in April

1973. He made the call to his rival, Joel Engel. Motorola was the first




37/38

company to incorporate technology into portable device that was

designed for use even outside of an automobile. By 1977, AT&T and

Bell Labs had constructed a prototype cellular system.

Each base station can communicate with other base stations. Base

stations are prominent by the size of their antenna above some

buildings in major cities and towns. A cell phone handset is a low

power radio transmitter/receiver and a kind of computer. It can

transmit as well as receive electromagnetic waves of certain frequency

from its closest base station when it is powered on. It transmits a

signal to the base station of its parent company every few seconds to

enable computers attached to these transmitters/receivers maintain

latest information about all the handsets distributed/registered by a

company present in a cell. This is done with the help of computers,

that can communicate this information from one base station to

another. Thus base station of each cell knows the location of every

powered on handset at any instance of time. One can say a cell phone

is a Personal Telephone.

We can call the present century is the Century for freedom to

communicate.

The last word

That was the story to tell and to know. How did you like it? Now that

you know this story, here are a few questions for you. You would have

observed that although our ancestors belonged to the Indus valley

civilization, one of the most advanced ancient civilizations, there is

hardly any Indian who invented or discovered anything that is useful

for communicating today. Why is it so? Will it always be so? Would you

like to invent? Are there any terretories in communication yet to be

explored?




38/38

References:

1. http://inventors.about.com/library/inventors/bl_history_of_communication.htm2. http://www.mediahistory.umn.edu/time/alltime.html

3. http://www.kids.net.au/encyclopedia-

wiki/ti/Timeline_of_communication_technology

4. Communication and Broadcasting, Harry Henderson, Universities Press, 1999

5. The Telecom Story, M. Sundararajan, National Book Trust, 2004

Documents

17561 Messages Through Ages