An Encyclopedia of the History of Technology part 74 doc

PART FOUR: COMMUNICATION AND CALCULATION
712
A station agent telegraphed the page number with his first signal, and the
number of the word on the page with his second. Phrase and place-name
vocabularies, each again of 92 by 92 items, were developed; to distinguish
them, an initial signal indicated the code; the second, the page; and the third,
the item on the page.
No public excitement over the semaphore system occurred until 1 September
1794, when Condé was recaptured. The Convention then ordered the extension
of the line from Lille to Ostend, and a second line to be built to Strasbourg, which
was completed in 1798 with 46 towers at a cost of 176,000 francs. Despite the
practical success of these telegraph lines, they did not bring in revenue, but rather
entailed great expense; maintenance and service in the eighth year of use cost
Figure 15.2: Three stages in the evolution of the telegraph: (a) Chappe’s 1794
semaphore; (b) von Soemmering’s 1809 electrolytic telegraph.
INFORMATION
713
434,000 francs. Napoleon, losing enthusiasm for the venture, reduced the
appropriation to 150,000 francs a year, and cancelled a planned Paris-Lyon line.
Claude Chappe thought that his system might benefit business, as well as give
an advantage in war. During the Restoration, interest in the telegraph increased
and Chappe’s dream was at last realized—but he committed suicide in 1805,
despondent over the slow progress and suffering from bladder trouble. However,
his brothers continued to perfect the system; Abraham worked at overcoming the
fog problem, anticipating British use of hydrogen fires during the Second World
War. Semaphore systems remained in use well into the nineteenth century, even
after the electric telegraph was developed (see p. 714).
Figuier, writing in the 1860s, claimed that aerial telegraphers could send a
dispatch in two minutes from Lille to Paris (a distance of 240km (150 miles),
requiring 22 stations); in three minutes from Calais (270km (168 miles) and 33
stations); in eight minutes from Brest (600km (373 miles) and 54 stations); and in

twenty minutes from Toulon (more than 1000km (620 miles) and 100 stations).
The equivalent rates of speed would be, respectively, 7200, 5400, 4500 and
3000kph; even the worst case is three hundred times better than the then fastest
system—a relay of horses and riders, such as the famed Pony Express in the USA.
The electric telegraph
The idea of the electric telegraph preceded its practical possibility by many
decades. Chappe’s semaphore had demonstrated the need for rapid
Figure 15.2: (c) Cooke and Wheatstone’s 1837 5-needle telegraph.
PART FOUR: COMMUNICATION AND CALCULATION
714
communication of messages, but until electricity was better understood, little
progress was possible. There were attempts to do the job with static electricity,
but the high voltage and very low current characteristic of this form of
electricity did not allow reliable transmission beyond a few metres.
The inventor of the earliest electric telegraph did not wait upon the
epochmaking discoveries of Oersted, Faraday and their contemporaries (see
Chapter 6). In Germany, S.T. von Soemmerring observed that electric current
passed through an acid solution caused bubbles to appear (electrolytic
decomposition of water into its elements, hydrogen and oxygen). He invented
a telegraph system using this principle in 1809, which used 26 parallel wires to
transmit letters of the alphabet a distance of up to two miles (Figure 15.2 (b)).
He even designed an ingenious alarm to alert the receiving operator (this was
really the first relay, although not electromechanical). However, the expense of
so many conductors made the system economically impracticable.
André-Marie Ampère, in 1820, invented the galvanometer which enabled
electricity to be measured, and suggested using a galvanometer needle for
telegraphy. W.F.Cooke and Charles Wheatstone invented a five-needle
telegraph, which was patented in 1837 (Figure 15.3 (c)). Although still a
parallel data-communication system like Soemmerring’s, this reduced the
number of wires to only six, by representing alphabetic characters with a 2-

out-of-5 code. By 1839, they had set up a 13-mile telegraph for the British
railways using this system. It was not long before the cost of multiple
conductors stimulated reduction of the number of needles to two, and finally
to one. So the needle telegraph became the first serial data-communications
system, with codes defined by sequences of needle deflections to make up
each character.
Samuel F.B.Morse, already a noted American painter, became interested in
the possibilities of electrical communication in the 1830s. He built a telegraph
system in 1835: the sender used notched metal strips to encode the alphabet,
and the receiver was an electromagnetically-driven pendulum with a pencil
attached which wrote the coded signals on a moving roll of paper. Morse’s
knowledge of electricity was rudimentary, but by 1837 he had patented the
telegraph, replaced the type-bar sender with what we now call a telegraph key,
and simplified the receiver to a pen which put marks (dots and dashes) on
paper tape. Early telegraphs used two wires, but it was soon found that one
would do, the earth acting as the return path.
With some government support, Morse started a telegraph service between
Washington and Baltimore in 1844. When the line was extended to New
Jersey, it attracted customers in the financial community who appreciated the
commercial value of instantaneous communications. The visual receiver was
replaced by a sounder, because operators could transcribe aurally transmitted
codes to paper faster than the marks on paper tape. This early human-factor
discovery shows the importance of inventor-user interaction in bringing an
INFORMATION
715
idea to practical fulfilment. The so-called Morse code was actually the work of
Morse’s assistant, Alfred Vail.
The telegraph was one invention which did not have be marketed; the
public was eager and ready to pay for good communications. By 1852, more
than 18,000 miles of wire covered the eastern third of the USA, with service

provided by many small companies. In 1856, Western Union was created, and
extended the telegraph to the west coast in 1861 with government support; a
message cost senders $1 per word.
There had been several attempts to develop submarine cables for
telegraphy, but the first, under the English Channel, ruptured in 1850.
Improvements in cable-making, and the development of specially equipped
cable-laying ships, enabled construction of a reliable link from Dover to Calais
in 1851. A much more audacious undertaking, a transatlantic cable, was
proposed by an American, Cyrus W.Field, in 1856, and was successfully laid
by HMS Agamemnon between 1857 and 1858. However, a few months
afterwards, operator error put 2000 volts across the cable which rendered it
unusable.
It was not until after the American Civil War, in 1865, that Field attempted
another link; this time, the cable was spun out from a single ship, Brunel’s
Great Eastern. This sail-and-steam leviathan carried almost 5000km (3,100
miles) of cable weighing over 5000 tonnes. However, after laying 2000km
(1250 miles) between Ireland and Newfoundland, a defective length snapped;
after ten days’ unsuccessful grappling, the spot was marked and the attempt
abandoned. Another cable was manufactured by the Telegraph Construction
and Maintenance Company of the UK, and laid by the Great Eastern in 1866:
the commercial communications link so long sought between Europe and the
United States was at last established.
The first telecommunications network—organizational rather than
physicalwas that of the Associated Press, begun in the 1840s by a group of
New York newspapers to share telegraph expenses. Many technical
improvements were made in both the United States and Europe, including the
paper-tape perforator of Wheatstone (1855), and the multiplex telegraph of
Emile Baudot (1874). However, the most radical departure, which led the way
to the modern era of telegraphy, was the invention of the teletypewriter (or
teleprinter) by E.E. Kleinschmidt in the US in 1928. This allowed operators to

compose messages using a typewriter-like keyboard to punch paper tape,
which was then torn off and fed into a tape reader for transmission. At the
receiving end, the message was printed out on paper strips (later, directly on a
roll of paper). Thus, the days of the telegraph operator, sending with a
lightning touch on the key, and listening to the clicks of the sounder were
ended. However, Morse is still used in radiotelegraphy, where it can get a
message through static and difficult transmission conditions when
electromechanical and electronic alternatives are unworkable.
PART FOUR: COMMUNICATION AND CALCULATION
716
Telex
The sending and delivery of a telegram has always been a hybrid type of
service, part electronic and therefore very rapid, part manual and therefore
slow and labour-intensive. The sender had to go to a telegraph office and
print out his message in capital letters on a special form; the clerk had to
count the words and compute the amount due from a tariff schedule; then
the telegraph operator had to key in the message. At the other end, the
reverse took place; the message would be printed out on a paper strip, cut
into segments and pasted on a form, and then had to be delivered by hand to
the recipient.
By the time most customers had their own telephones (the 1930s in the US
and Canada; later elsewhere), the US telegraph carrier Western Union would
accept outgoing telegrams over the phone, and read incoming telegrams to
recipients who were phone subscribers. However, the unique feature of the
telegram among public telecommunications services has always been the
delivery of a written message, providing legal proof to sender and receiver.
Most customers would insist on physical delivery even though the message
had been read to them over the telephone; in such cases, telegraph officers
would resort to the postal system.
For business users, the whole system seemed archaic. In the US they turned

increasingly to the telephone whenever written proof was not essential. In
Europe, with its many languages and complex cross-border tariffs, the
telephone did not have the same ease of use or economy. Therefore, when the
first telex network was put into service in Germany in 1933, a great unmet
demand was released. From its start, with only nineteen subscribers in Berlin
and Hamburg, telex service had an explosive growth. In Germany
subscriptions grew at more than 100 per cent annually up to the Second World
War; similar growth, but at lower rates, was experienced in other European
countries. By the early 1980s, the number of telex subscribers world-wide
exceeded 1.5 million, more than half of them in Europe.
Today, telex is a world-wide, switched public teleprinter service. Therefore it
is like the telephone, in that subscribers are loaned terminal equipment, can
dial up other subscribers themselves, can receive messages, and are charged on
the basis of time and distance. However, unlike the telephone, messages must
be keyed in and received on teleprinters. Up to the 1970s, the usual practice
was to keypunch a series of messages on paper tape, dial up the recipient’s
teleprinter, and put the strip of tape in the sender’s teleprinter; this store-and-
forward process has been greatly enhanced by the use of computers in telex
officers, and by microprocessors and electronic memory capability in terminal
equipment. Also, in store-and-forward operation, the same message may be
sent to many recipients (a type of message broadcasting), and re-dialling done
automatically when receiving terminals are busy.
INFORMATION
717
One of the greatest advantages of telex is that teleprinter equipment and
service available to subscribers is uniform throughout most of the world.
Unfortunately, a faster service, Teletype, was introduced in the US side-by-side
with Western Union’s telex, and until the FCC forced AT&T to relinquish their
public switched message service, conversion was difficult. However, since
Western Union took it over, computers do this conversion without customers

having to worry about it. The international telex system uses the five-level
Baudot code, which requires a shift from letters to numerals and back again, and
there is no provision for indicating letter-case. The speed of transmission is very
slow: 50 bits per second, equivalent to 66 words per minute (a word is defined to
be six characters, including space). In international practice, the telex system still
has these limitations, but within certain countries faster and more flexible
equipment is allowed. In the early 1980s, a completely new public switched
message service was introduced called teletex. It operates at 2400bps, 40 times
faster than telex, and allows upper-and-lower-case letters, formatting codes and a
host of other features: teletex can best be described as communicating word
processing. However, new equipment is required in both central offices and
subscribers’ premises; total cost is higher for low-volume users; and in the mid-
1980s teletex service was only available in a few countries. Therefore, it is
unlikely to displace telex in international use until the 1990s.
THE TELEPHONE
In addition to an understanding of electromagnetism, a knowledge of acoustics
and human hearing was essential to the development of the telephone.
However, with the exception of Bell, most of the early experimenters were
physical scientists, engineers or dedicated tinkerers, rather than biologists,
physicians or psychologists.
Acoustic transmission
The science of acoustics developed out of the theory and practice of music, and the
refinement of musical instruments. An understanding of the laws of harmony
started with Pythagoras in ancient Greece. Shorthand symbols had been used to
record Greek and oriental speech (ekphonetics), and between the fifth and seventh
centuries AD a system was developed to show melodic movement using symbols
called neumes. The staff was created in the ninth century—a single coloured line.
Guido d’Arezzo suggested using three and four lines, the latter becoming the
standard for recording Gregorian chants. Today’s five-line staff appeared in the
eleventh century, but did not come into general use until the seventeenth century;

some composers would like to have six or even eight lines.
PART FOUR: COMMUNICATION AND CALCULATION
718
In 1796 a German student, G.Huth, musing on ways to overcome the
disadvantages of Chappe’s semaphore (see p. 711), such as excessive operating
cost and interruption of service by fog and rain, hit upon the ideas of using
large speaking-tubes (megaphones). Specially selected and trained operators
would listen to the message from one tower, and turning their megaphones in
the direction of the next, repeat the message immediately. Huth wrote that
‘this… difference might deserve a different name. What could be more
appropriate…than the word derived also from the Greek: Telephone or
Fernsprecher?’
Actually, Huth’s idea was less practical than the semaphore, because visual
signals are usable over much further distances than voices or even whistles or
drum beats. The speaking voice, even using a megaphone or electronic
amplification, is audible only up to a few hundred metres; a human whistle,
screams and yodelling carry further. Mechanically aided sound-generation
systems, such as noisemakers and musical instruments are also useful; African
drums can carry messages for many kilometres. Today, aerosol-powered
shriekalarms can carry at least a kilometre, and police and ambulance sirens
can be heard over a radius of several kilometres even in noisy cities.
Sounds also can be sent through hollow tubes, and through denser matter
(liquids or solids) they can be transmitted much further and at higher speeds
than in air. In 1838, Romershausen proposed a telephone which would
transmit speech through narrow tubes. Modern hydrophones listen in on the
cries of dolphins and whales, and detect other underwater sounds over a range
of frequencies far beyond human hearing.
Electrical speech transmission
However, although such means could carry intelligible messages, there is less
privacy, greater interference from noise, and greater annoyance to the public at

large than in visual signalling. What was needed to make sound transmission a
practicable means of communication, just as with the telegraph before it, was a
better understanding of the nature and application of electricity. In 1837, about
the time that Cooke and Wheatstone were building the first commercial
telegraph system, Professor Page in Salem, Massachusetts, discovered that an
iron rod which was suddenly magnetized or demagnetized would emit sounds;
this came to be called Page’s effect, but no practical applications emerged.
In 1854, Charles Bourseul in France predicted the coming of speech
transmission, and outlined a method for its realization that was correct except
in one critical feature: he expected that it would be achieved using make/break
circuity (like the relay and telegraphy, which is digital) rather than with circuits
capable of handling continuous current (which is analogue). Philip Reis in
Germany constructed a telephone along the lines suggest by Bourseul in 1861,
INFORMATION
719
but was able to transmit only tones rather than speech. In 1868, Royal
E.House, who had invented a printing telegraph in 1846, patented what he
called an electrophonetic telegraph, but did not realize its capabilities to
transmit speech. Ironically, we are today on the threshold of ISDN (Integrated
Services Digital Network) which will transmit all signals—speech, video, text
and data—digitally.
The breakthrough came in 1876 when Alexander Graham Bell and Elisha
Gray almost simultaneously—and independently—filed patents for successful
speaking telephones. Although, after long patent litigation, Bell was awarded
priority, Gray’s system was technically superior. Bell was an early example of
the brain drain from the Old World to the New. His parents had emigrated
from Scotland to Canada after having lost two sons to tuberculosis, and Bell
later settled in Boston where he became a teacher of the deaf. From this
background, rather than as a physical scientist or engineer, Bell approached
the problem: as a teacher trying to find better ways to teach deaf students to

speak. For this purpose he had invented a special notation for recording
speech. Bell’s earliest working models used no external source of electricity,
and transmitter and receiver were almost identical. This system—the voice-
operated telephone—is still used over short distances. Switched telephone
systems require external power.
On 7 March 1876 the famous command, ‘Mr Watson, come here. I want
you!’ was uttered by Bell to his assistant, who instead of only hearing Bell’s
voice from the other room, heard it over the primitive induction device with
which they were experimenting. This, the first transmission of a human
voice over wire, happened only three days after the first telephone patent had
been issued to Bell. He had filed for this patent on 14 February, only three
hours before Gray had filed a caveat that he was working on a similar
device. Bell’s patent was probably the most valuable ever granted, giving
birth to what has become the world’s largest private service organization, the
Bell Telephone Company.
Bell Telephone was formed only a year afterwards, the first two telephones
being leased to a Boston banker. Also in 1877, Bell, who had married the deaf
daughter of his first backer, Thomas Sanders, went to England on his
honeymoon; mixing business with pleasure, he gave many demonstrations,
and presented Queen Victoria with a pair of telephones. However, although
the British Post Office’s chief engineer recommended obtaining rights to
manufacture and use the new technology, the Post Office claimed that this was
not necessary to protect its monopoly—because the telephone was just another
form of telegraph.
In 1883, Edison discovered what eventually became the basis for signal
amplification in both wire and wireless communication—he observed that
when he added another element (electrode) to a light bulb, that current could
flow across the evacuated space between filament and electrode. This came
PART FOUR: COMMUNICATION AND CALCULATION
720

to be called the Edison effect, but was only a laboratory curiosity until 1904,
when Fleming invented the two-element rectifying diode: shortly afterwards,
in 1906, Lee de Forest added a third element which enabled small voltage
changes to control the flow of large currents, giving birth to the triode and
the age of radio.
THE GRAMOPHONE
All sounds, whether voice, music or simply noise, depend upon physical
vibration of some medium—if our ears had the ability to detect extremely low
frequencies and faint sounds, we might even hear the ripples in a calm lake
and not just the roar of ocean waves. Unlike the extremely limited ability of
our eyes to sense the immense range of the electromagnetic spectrum directly
(less than one per cent), we can hear about ten per cent of the sound spectrum
which is inherently limited because physical molecules must vibrate to emit
and transmit sound.
It has been reported that a visitor entering an ancient Chinese temple is
greeted with the Chinese equivalent of ‘close the door’ upon entering and,
when he does, ‘thank you’. The mechanism for this automatic doorman is said
to be a pointed object which moves over a serrated strip when the door is
opened, and then moves backwards when it is closed, the Chinese for ‘thank
you’ being the reverse of ‘close the door’. If true, this invention is similar to
noisemakers, where one stick is rubbed over another which has a regular
pattern of notches cut into it; however, the ability to cut notches so that a
semblance of the human voice is reproduced strains credulity. Practical systems
for the automatic recording and reproduction of sound have become available
only recently, and voice synthesis and recognition are still in their infancy.
Mechanical sound recording and reproduction
Techniques of recording vibrations occurred before means were found to
reproduce them. In 1857, Leon Scott de Martinville, designed a device for
tracing soundwaves on a cylinder covered with lampblack, which he called a
‘phonautograph’; however, he could not find a way to replay the sound. In

1877, Charles Cros in France outlined a scheme to convert Scott’s waveform
trace into a physical groove by photoetching, and play the sound back by a
point attached to a diaphragm which followed the groove. He dubbed this
device the ‘paleophone’, but lacked funds to put the idea into practice.
The first machine actually built which could both record and reproduce
sound was Edison’s 1878 cylinder phonograph, for which he filed the first
detailed patent application in England. This had been preceded by an 1877
INFORMATION
721
patent for a means to record Morse code by making indentations on paper
stretched over a disc or cylinder, and another which outlined a method for
transmitting the human voice over telegraph wires.
The seminal 1877 Edison patent contained in its specifications not only
details of his original tinfoil-on-cylinder model, but also claimed disc recording,
wax materials, electromagnetic (rather than acoustic) recording and
reproduction, mass production of recordings and amplification. Unfortunately,
Edison failed in his efforts to make the equivalent claims in the US. As a
consequence, a tangle of litigation marred the early decades of the
phonograph, just as it did the contemporary invention of the telephone. In fact
Bell, with his brother and Charles Tainter, patented a rival system, the
graphophone, in the mid-1880s which used removable waxed-paper cylinders.
The US patent, dated 19 February 1878, was titled ‘Phonograph or
Speaking Machine’. The drawing showed a spiral-grooved cylinder wrapped
with tinfoil; on one side was a short horn (the mouthpiece) containing a
diaphragm to which a rounded needle (the stylus) was fastened at right angles;
opposite, a larger horn with an upward-facing opening was similarly outfitted
(the speaker). Thus, when Edison spoke his famous ‘Mary had a little lamb’
into the mouth-piece, he was startled to hear his voice reproduced on the other
side a fraction of a second later. Bell’s first telephone (see above) was similar in
its simplicity, being able to act either as sender or receiver.

In 1888, Edison also patented a wax-cylinder machine, but one year earlier,
Emile Berliner had patented his gramophone; although depicted in the drawing
as a cylinder machine, by the time he built his first model a year later, it was a
disc machine. Another innovation introduced by Berliner was lateral recording
of sounds in spiral grooves. Scott’s tracings had been lateral, but Edison and his
followers had employed vertical (hill-and-dale) recording. By 1895, Berliner had
combined his flat disc, Scott’s lateral recording method and Bell and Tainter’s
wax coating, and formed the basis of the modern mass-production recording
industry. Edison never exploited the alternatives of his 1878 British patent,
sticking with cylinders almost until the First World War; reluctantly, in 1912 he
brought out a disc phonograph. He was right about some of the advantages of
the cylinder: it provides identical grooves over the entire surface, rather than
spiralling to a smaller and smaller radius; and hill-and-dale recording can handle
a much greater dynamic range without shortening recording time.
The original application of the graphophone and phonograph was not in
entertainment but in business. In the late 1880s, the North American
Phonograph Company was formed to rent out both types of cylinder machines
to record dictation (for a similar machine see Figure 15.3); however, the
graphophones proved unreliable, and the confusion of offering two
incompatible machines to customers led to failure of the company. Rather, it
was as an entertainment medium that the phonograph and gramophone scored
their early successes. In 1888, Gianni Bettini in New York used a phonograph