| Part 1 – Whispering Wires | |
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The Development of the Electric Telegraph
Before the Electric Telegraph
Sending written messages in the early nineteenth century was a luxury reserved for the wealthy, businesses or the Government. Ordinary people had only two options – either to carry the message themselves or send it with someone else. How quickly these messages reached their destination was entirely dependent on the speed and length of time a horse could travel.
During the first quarter of the nineteenth century all the major towns and cities of the British Isles were linked by an efficient and highly organised system of horse-drawn coaches which operated to strict timetables. Operators gave their coaches fanciful names such as `Flyer’, `Rocket’ or `Lightning’ to suggest speed. In addition there were the mail coaches. The cost of sending a letter was borne by the recipient and the charge varied according to the distance the letter had to be carried. Although coaches changed horses at regular intervals it was still a relatively slow method of communicating. In 1835, the journey from London to Edinburgh took forty-eight hours.
In 1839 the cost of sending a letter in Britain was:
|
up to 20 miles 5d (32km, 2p) |
up to 120 miles 9d (193km, 4p) |
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up to 30 miles 6d (48km, 2.5p) |
up to 170 miles 10d (274km, 4p) |
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up to 50 miles 7d (80km, 3p) |
up to 230 miles 11d (370km, 5p) |
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up to 80 miles 8d (129km, 3p) |
up to 300 miles 1/- (483km, 5p) |
The development of the railway network, which began in earnest in the 1830s, made an enormous difference to the speed of communications. Not only could passengers travel from place to place more quickly, so too could the mail. Within a relatively short time Britain was covered with a web of railway lines which made it possible to travel to almost any part of the country within a day. Horse-drawn coaches soon fell victim to competition from the railways and within a few years had disappeared completely.
In 1840 a flat-rate postal service, the Penny Post, was introduced by the Postmaster General, Sir Rowland Hill. For the first time a letter could be sent anywhere in Great Britain for a penny (about 0.5p) using a prepaid postage stamp. Although it was still a relatively expensive service, it made a message carrying system available to a much wider section of the population than before.
Written messages destined for overseas were carried mainly by sailing ships which depended on the force and direction of the wind to reach their destination quickly. However, steamships were beginning to replace sailing ships, cutting voyage times and making the world seem a slightly smaller place. The first ship to cross the Atlantic under continuous steam power was the 714 tonne Sirius in 1838.
The Development of the Electric Telegraph
A series of major discoveries in the latter half of the eighteenth and early part of the nineteenth centuries sparked an intense interest in electricity. In 1746 van Muschenbroek, a Dutch physicist, developed the Leyden jar, a device which could store and discharge electricity. In the same year the Abb Nollet demonstrated one of the effects of electricity. He arranged a circle of monks, each connected to his neighbour by an iron wire, and then applied an electrical current to the `circuit’. The hysterical movements of all the monks proved that the current had travelled around the `circuit’. It was noted that all the monks felt the shock simultaneously, from which it was deduced that the time the electricity took to travel round the circuit was so small as to be negligible.
There were also some attempts to use electricity to send messages but the methods used were usually cumbersome, unreliable and invariably impractical.
In 1816, Francis Ronalds, who was fascinated by electricity, developed an electric telegraph (using static high voltage electricity) and succeeded in sending messages through eight miles of iron wire suspended above his garden in London. He showed that the transmission of electrical signals was instantaneous, although it is unlikely his equipment would have worked over long distances. He realised the potential of his telegraph for sending vital military messages between London and Portsmouth and offered to demonstrate it to the Admiralty. They declined, saying that they had no intention of using anything other than their mechanical semaphore.
This employed two wooden semaphore arms which could be arranged in a variety of different positions, each one corresponding to a letter of the alphabet or a figure. Although it remained in use until 1847 it was slow (a short message could take up to fifteen minutes) and could not be used at night or during poor visibility. Sending messages over long distances required a series of towers. Each one received a message from the previous station and then re-transmitted it to the next one. Like Chinese whispers there was always the risk of errors creeping in and distorting the original message.
In 1819 Hans Oersted, a Danish scientist, showed that when a wire carrying an electrical current was placed near a magnetised needle, the needle moved. He had discovered the electromagnetic effect which was to have the most profound influence on the development of telecommunications.
A few years afterwards William Sturgeon, a Lancashire shoemaker, succeeded in making the first electro-magnet but it was a Russian, Baron Pawal Schilling who realised the potential of the electromagnet in telegraphy. In 1832 he demonstrated an electric telegraph, using electromagnets to attract iron needles, to Czar Nicholas in Berlin. He simplified his system so that it used only one needle, but died before he could develop his telegraph further.
Meanwhile, in Britain William Cooke abandoned medicine and instead directed his attention to electrical telegraphy. His interest may have resulted from watching his father and Francis Ronalds transmit messages from the coach house to the tool shed at the end of the garden when he was a boy. In 1836 he attended a lecture in Heidelburg at which one of Baron Schilling’s needle telegraphs was demonstrated. It must have made a tremendous impression on him for within three weeks he had made a telegraph of his own. He was not convinced that his telegraph would be able to transmit over long distances so he arranged a meeting with the noted physicist Professor Wheatstone, who was interested in both sound and electricity. From this single meeting developed a working partnership which culminated in the demonstration of the first working electric telegraph in the world.
Cooke and Wheatstone’s telegraph employed five iron needles which when not in use rested in a vertical position. Each needle could be moved either to the left or the right by electromagnets. To transmit a letter of the alphabet two switches were pressed which caused two needles to move and point to the appropriate letter. By pressing different combinations of switches any one of twenty letters could be transmitted. Unfortunately J, C, Q, U, X and Z had to be omitted making it difficult to send some words. Alternative methods were adopted to spell words such as `queen’, `quiz’ or `axe’. Despite its shortcomings, the advantage of their equipment was that it could be used by unskilled operators.
Cooke’s business acumen played a crucial role in the success of their telegraph. He realised the potential of an almost instant method of sending messages for the new railway companies, and in 1837 he arranged a demonstration between Euston and Camden stations, a distance of 1.5 miles (2.4km). There were problems in insulating the iron wires which carried the signal. The wires were covered with cotton and buried in iron pipes beside the railway line. While the wires remained dry there was no problem but if they became wet the insulation failed. Nevertheless, the equipment clearly impressed the Directors of the Great Western Railway who allowed a trial to take place between Paddington and West Drayton. The trial was a partial success. The company did not accede to Cooke’s request to extend it to Bristol, but did agree an extension as far as Slough, provided railway messages were carried free of charge. Cooke overcame the insulation problems by suspending the wires from iron posts using glass insulators. This extension was paid for by Cooke and Wheatstone and to recover some of the expense they offered the public the opportunity to send messages at a shilling (5p) a time.
Although the five needle telegraph was easy to operate it required six wires. It was soon replaced by a single needle instrument. Each letter of the alphabet was given a code of right and left needle movements, and in this way messages could be transmitted. However, this required skilled operators.
In 1844 the first public telegraph line opened along the railway line between London and Gosport. It provided the Admiralty with a direct link to the naval base at Portsmouth.
Slowly, the advantages and potential of the electric telegraph were being realised. However, it was the use of Cooke and Wheatstone’s telegraph to apprehend a criminal that caught the public imagination.
The Cords that Hung John Tawell
On New Year’s Day 1845 John Tawell travelled by train to Slough with one purpose in mind to murder his mistress. They met and he emptied the contents of a phial of poison into her drink. Rather naively he expected that when she finished her drink she would expire conveniently at his feet. Instead his victim let out a bloodcurdling scream and in his panic he ran out into the street to make his escape.
Neighbours also heard the scream and, opening their doors to find out what the commotion was about, saw him hurrying up the road looking very agitated. Tawell made his way to the station where a train was about to depart for London. Settling back in his seat, as the train sped along the tracks, he was convinced he had escaped and that once in London he could disappear in the crowds.
Meanwhile, the murder had been discovered and news soon reached the station of the man who had aroused suspicion. As he sat in the train he could not have known that travelling along the wires beside the speeding train flashed a message which would arrive in London long before he did. The message read:
A MURDER HAS JUST BEEN COMMITTED AT SALT
HILL AND THE SUSPECTED MURDERER WAS SEEN
TO TAKE A FIRST CLASS TICKET TO LONDON
BY THE TRAIN WHICH LEFT SLOUGH AT 7.42
PM. HE IS IN THE GARB OF A KWAKER WITH A
GREAT COAT ON WHICH REACHES NEARLY DOWN
TO HIS FEET. HE IS IN THE LAST
COMPARTMENT OF THE SECOND CLASS
COMPARTMENT.
There was some confusion at Paddington about the word `KWAKER’. The telegraphist thought it was an error but after it was transmitted a third time he realised that it represented the word `QUAKER’, the five needle telegraph being unable to transmit the letters `Q’ or `U’.
Immediately the police were summoned and were at the station when the train pulled in.
Tawell walked out of the station, quite unaware that he was being watched, and caught an omnibus. The conductor who collected his fare was a policeman in plain clothes who also followed Tawell when he left the bus. At his lodgings the constable confronted him and asked if he had just come from Slough. Tawell answered `no’ and was promptly arrested. He was later tried, found guilty of murder and hanged.
The American Dimension
Cooke and Wheatstone are generally credited as having developed the first working electric telegraph, but at almost the same time Samuel Morse, working in America, was developing his own. At first he concentrated on designing a machine which could record the incoming message on a moving paper tape, but he simplified his equipment so that the receiver made only a sound. He also devised a code which still bears his name. Morse’s telegraph and code were soon adopted throughout the world and it is his name that is most associated with the electric telegraph.
Preparatory Activities
Make a list of all the different ways of communicating (not just those used today). Beside each one ask pupils to write any advantages or disadvantages that they can think of.
(Although it is still possible to send an international telegram, there is now no inland telegram service in the British Isles. It may be necessary to explain to pupils what a telegram is).
Extension Activities
Read the story about the arrest of the murderer John Tawell. Ask pupils why they think the police did not arrest him when he stepped off the train in London.
Identify the Thief
Police have just received this telegram.
Great Western Railway Telegram A MURDER HAS JUST BEEN COMMITTED AT SALT
HILL AND THE SUSPECTED MURDERER WAS SEEN
TO TAKE A FIRST CLASS TICKET TO LONDON
BY THE TRAIN WHICH LEFT SLOUGH AT 7.42 PM.
THIEF WEARS RING
AND CARRIES BAG. HE SMOKES CIGARS, HAS A
BEARD AND HANKERCHIEF IN TOP POCKET. HE
CARRIES UMBRELLA AND WEARS HAT. HE IS IN
THE LAST COMPARTMENT OF THE SECOND CLASS
COMPARTMENT.
The police go to the station. When the train arrives they watch the people who get off the train. Which person do you think they arrest?
Make a Working Telegraph
You will needIt is perfectly possible to construct a telegraph using miniature light bulbs. However, the incandescent bulb was not invented until 1870 and so the early pioneers had to use other ways of detecting an electrical current. This telegraph is a simplified version of that developed by Samuel Morse.
Bend a strip of steel and mount it on a block of wood to make the tapper or switch. (You could use a press button switch instead.) Use screw-eyes and brass cups as terminals.
For the sounder, wind the one metre length of wire around the nail to make an electromagnet. Fasten a strip of steel so that its free end rests about 2mm above the nail head.
Use two 1.5 volt batteries, making contacts from bent paper clips secured with screw eyes and brass cups.
When the circuit is completed, the nail is magnetised attracting the steel strip with a loud click. When the circuit is broken the steel strip returns to its normal position.
Because the nail is made of steel it will become partially magnetised after use. This may prevent the steel strip from returning to its normal position when the circuit is broken. Slightly increasing the gap between the nail and the strip usually has the desired effect.
In a Few Words
Telegrams were expensive to send so most people only sent one when they had an urgent message to send.
Every word cost money, even those which made up the address, so people tried to make their messages as short as possible. It was important, though, that the message was clear.
You have invited a friend to stay at your cottage in the country.
The full directions are: get off the train at Woolcombe. Turn left outside the station and walk as far as the crossroads. Turn right. You will pass a church and a Post Office. A little further on you will pass the village pond. Turn left by the pond and the third cottage on the right is Honeysuckle Cottage.
Your friend must leave in a few hours. You will have to send the directions in a telegram. What should the telegram say? Try to make your message as short as possible.
Work out how much your telegram cost to send. Could you have saved any money by making it shorter?
Keeping it Short
The year is 1860. Imagine that an aunt is meeting you at the railway station. They have never seen you before. There is no time to write to them and you do not have a photograph. You will have to send a telegram instead.
Write a telegram describing yourself so that your aunt you will be able to recognise when you arrive at the station. You have enough money to send 20 words. Six of these will be used for the address, so your message can only contain fourteen words.
Can you describe yourself in only fourteen words?
Show your telegram to a friend. Do they think it describes you in enough detail?
Completing the Circuit
Put together a circuit like the one in the picture.
You will needMake a gap in the circuit using either a block of wood and two drawing pins or with a piece of card and sticky tape. The gap should be about 5cm wide. Because the circuit is not complete the bulb should not light up.
Lay the blade of a pair of scissors across the gap. Does the bulb light up?
Test lots of different materials. Record whether they make the bulb light up.
Those which make the bulb light up are called conductors. Those which do not make the bulb light up are called non-conductors or insulators.
What might insulators be useful for?
Codes
Telegraph messages were usually sent using Morse code. Each letter
of the alphabet was represented by either a dot or a dash. [A dot was made
by tapping the sender very quickly; a dash by holding down the sender for a
little longer.]
Here is the Morse code.
You do not need an electric telegraph to be able to send messages
in Morse code. You can use any two things which make different sounds. For
example, you could use a drum and a triangle. One beat on the drum could
stand for a dash and one beat on the triangle for a dot.
Work with someone else. Try sending a short message in Morse code.
What other codes do we use today?
AlternativelyMake a simple telegraph using a battery, wire, switch and bulb. Use Morse code to send a simple message. Press the switch for a short time to show a `dot’ and hold it down longer for a `dash’.
[When Morse code was first used there were no electric light bulbs. The `dots’ and `dashes’ were represented by clicks when an electromagnet attracted a piece of sprung steel.]
Newspaper Article
You work for a newspaper. The Editor has sent you to watch a demonstration of the new electric telegraph invented by Cooke and Wheatstone. You are excited by what you see.
Write an article for the front page of the newspaper. You could say what the machine does, what it looks like and perhaps how it works. You might say whether you think it will catch on. You can draw a picture if you like.
Advert for Telegraph
Write an advert for the newly invented electric telegraph to persuade people to use it. Keep your advert simple and eye-catching.
Planning a Telegraph Route
The map shows three towns, A, B and C. There are also hills, areas of marshy land and a lake. You have to link the three towns with a telegraph line as cheaply as possible.
