THE
MUSEUM OF
TECHNOLOGYThe Great War and WWII
[1850-1980]
Registered Charity No 1140352
THE
MUSEUM OF
TECHNOLOGY
The Great War and WWII
[1850-1980]
Registered Charity No 1140352
Home: Telegraphy: Telegraphy, a Brief History
Jungle Drums, Indian Smoke Signals, the Penny Post, a Ships Telegraph.
All these were means of conveying a message from one place to another
without actually going there in person. The ships telegraph sends a
signal from the bridge to the engine room by mechanical means to
instruct the engineers whether to go forward, fast or slow. The Penny
Post
is hand written and would be conveyed on horseback. The former is quick
but limited in information the later is full of information but is very
slow. At this time nobody would have considered
sending messages using electricity along a wire. Such things were
incomprehensible.
Many people have been responsible for the evolution of the ‘The Talking Wire’ only the key players are mentioned here.
In the late 1780,s Luigi Galvani (1737-1798)
made frogs legs jump using
an electric charge, static electricity could be generated by a static
generator and stored for a short time in “Leyden” jars, this could be
fed along a length of metal and positioned on a dead frog, it was noted
that the legs of the animal jumped in response. He called this ‘animal
electricity’. The idea of sending a signal with electricity and
producing a response via a line of metal was evident, the experiment
was acclaimed as a breakthrough in medicine, namely the effect of an
electric charge on a mortal body ‘Electrophysiology’ Galvani had also
provided a response to the presence of this strange phenomenon called
electricity, he called it an electric fluid.
A breakthrough came in 1800 when Alesandro Volta (1745-1827) created
electricity using a chemical composition called a “Volta Cell” which
not only produced a charge but also maintained it for a period of time.
He was sceptical about Galvani’s ‘animal electricity’. Volta
also
created the first battery, effectively a string of cells giving higher
voltages. In 1776 he remotely operated (fired) a pistol in
Milan
from a Leyden jar in Como, the current travelled along a wire suspended
on wooden boards.
In 1820
Hans Christian Oerstead (1777-1851)
noticed, by accident, that a
compass needle deflected when placed near a wire carrying an electric
current, creating more turns in a coil over the needle increased the
sensitivity. This device was called a “Multiplier”. The success of the
Multiplier for measuring current led to it being renamed “Galvanometer”
after Galvani’s experiments with frogs legs.
The combination of the battery and Galvanometer heralded the start of
Telegraphy, the remaining problem of power losses over long distances
still
remained, the electromechanical relay would solve this.
Joseph Henry (1797-1878)
invented the electromechanical relay
in 1835. A coil of wire wound round a metal core carries a small amount
of
power that magnetises and pulls in a lever closing a switch which can
carry a large amount of power, (sometimes called an amplifier), if
placed
at regular intervals along the wire it is possible to send a signal
around the globe. Using the natural resistance of earth as one path for
the signal, only one wire is needed.
Charles Wheatstone (1802-1875) built a Five needle Telegraph
in 1837, after William Cooke (1806-1897) had observed a similar
experiment in Heidelberg in 1836, from an idea by Baron Pawel Schilling
demonstrated around 1832. The device pointed directly to characters in a matrix
but only 20 letters were used, omitting the letters C,J,Q,U, and X.
Wheatstone's telegraph was commissioned by the Great Western Railway in 1837, being the first
commercial service in the world, operating from Euston to Camden Town. One
drawback was the cost of cabling the five needle system which required six wires
to operate or five wires and a common earth. Within 3 years this was reduced to 3 wires for a
two needle system because as wires were damaged
the five wire system ceased to work. The new two-needle system,
requiring a coding book, was first installed on the Paddington to West
Drayton line and was fully operational by 1839, leading to its use on
nearly all lines running out of London. By 1846 the telegraph covered
most of the main lines in England as far as Edinburgh.
The success enabled Cooke to form his own company
the ‘Electric Telegraph Company’ using Wheatstones patents freely, he
eventually bought out Wheatstone enabling him to develop other
scientific ideas, one of which was his successful Printing Telegraph.
By 1852 the company had become responsible for establishing over 6000
miles of telegraph lines in Great Britain. The general public at this
time were largely excluded from using the service as it was primarily
for the railways, if the public wanted to use the system they had to go
to the nearest Telegraph office located near a railway station. With
the introduction of Morse code telegraphy became more popular and
whereas the railways were using specialist methods of communication the
systems for general public communication started to use Morse code.
Other companies would ensue, after 1851 when telegraph lines were
established with the continent, the coding feature of Morse’s invention
was taken over by the railways and other commercial lines in Britain.
Prior to Cooke and Wheatstones work, Samuel Finley Breese
Morse (1791-1872)
commenced work on his telegraph system in 1832.
Morse was an artist and was commissioned to do a painting in New York. Whilst there he received a letter from his father stating ‘your wife is dead’, no more information was received. Morse returned home to New Haven, he had been unaware that his wife was sick. He was so moved that he abandoned his painting to develop a means of long distance communication. In 1836, helped by Alfred Vail (1807-1859), he improved his system which used just one wire and went into operation in 1846. The message was received on paper tape using a stylus to indent marks on the paper, known as a morse register, replaced by the morse sounder when it became possible to follow the clicks of the register. Morse developed a code so that the marks could be read as dots and dashes.
Some claim Morse Code should be called Vail Code. Although the original dots and dashes were attributed to Morse, the code eventually used was created by Vail. Morse’s code used numbers only, Vial's code was completely different expanding it to alphanumeric characters. Morse also had problems with his system in achieving distances of more than a few hundred yards, a problem which Vail helped solve. Vail also invented the 'morse key' around 1848 along with many other ideas. Vail became disillusioned with Morse receiving all the praise and decided to leave his company, he left Morse with the message ‘I have made up my mind to leave the telegraph to take care of itself since it cannot take care of me’.
Even though Morse introduced Morse Code in the early 1840’s it was later adopted by Wheatstone with his Single Needle System which now also required only one wire.
Without the great financial help provided to Wheatstone, and with Morse lagging behind by 4 years, the Wheatstone system became the commercial success. This, even though Wheatstone’s needle was cumbersome needing the movement of a handle to move the needle left or right . Morse Code replaced the needle movement with dots and dashes (short or long periods or marks).
Many variations of equipment were developed including the ABC Telegraph, Morse Inkers and the Double Plate Sounder and most signficantly for modern communication the Baudot Character Printer using a 5 bit code and requires 5 wires,.
Eventually undersea cables surrounded the world all sending Morse code, characters were converted on a keyboard to a paper tape consisting of two holes side by side, one side a dot the other side a dash, converted back at the other end. As undersea cables were often busy, the tape was queued until its allotted time day or night. Morse’s system had became world wide. Wheatstone’s system still exists in various forms in signal boxes in the UK, but never became universal.
Morse Code as an
international means of communication declined in the 1980’s, being
officially made oboslete by the French navy in 1997. However it
continues in widespread use by Radio Amateurs who value its ability to
achieve communication in difficult conditions and with low
power.
Three letters SOS (Save Our Souls) persist to this day ... --- ... and,
in your mobile phone, you may be familiar with SMS ...--...
Both Wheatstone Telegraphs and Morse Code required expert
operators
to intrepret the signals into alpanumeric characters. Machines like the Baudot Character Printer de-skilled the task by allowing characters
to be typed and printed, they could be used by low paid operators but
they required five wires to operate. Eventually
electro-mechanical machines such as the Creed Teleprinter were
made which, using a rotor, could take the five bits of information
and send them in series along a single wire with series to parallel
conversion occuring at the receiving end. The ideal combination of cost
and usability had been achieved. Electro-mechanical machines
were replaced in the 1970's with computers, the 5 bit Baudot Code grew
into 7 bit ASCII code allowing 128 characters to be coded. Today ASCII
is replaced by Unicode, a 32 bit code which can encode every
characterof every language of the world, but the basic principles of
the modern Internet age are still those of Wheatstone and Morse.
More Telegraphy from the Museum of Technology
© The Museum of Technoloy, the Great War and WWII, 2009