Technology & Medicine › Industrial revolution
Electric telegraph
1837 (Cooke & Wheatstone; Morse); Morse code line 1844· Invention or discovery· Communication & computing
Mostly agreedGood evidence; some details, dates or numbers uncertain.
Electric pulses sent through wires carried coded messages almost instantly over long distances.
See it on the Technology & Medicine map →How it works
A battery at one end sends current down a wire; at the other end it moves a needle or clicks an electromagnet. Cooke and Wheatstone patented a needle telegraph in Britain in 1837. In America, Samuel Morse, with Alfred Vail, developed a simpler system and the dot-dash code; the Washington–Baltimore line opened on May 24, 1844, with 'What hath God wrought'. By 1861 a line crossed the United States.
Why it mattered
For the first time, messages traveled faster than people, enabling news wires, railway control, national markets and near-real-time prices.
How we know
Patents and court cases, the original 1844 message tape at the Library of Congress, and company and railway records.
Still unknown or debated
Who invented it is contested: Schilling in Russia, Gauss and Weber in Germany, Cooke and Wheatstone, Morse and Joseph Henry all have claims; Vail's share of Morse code is debated.
Inside this (2)
Connections (7)
▸Railways were signalled by the Electric telegraphWell documented
The connection
Trains sharing tracks needed to know whether the line ahead was clear. Cooke and Wheatstone's first commercial telegraph ran beside the Great Western Railway, and railways became the telegraph's first big customer. Wires followed rail lines, and telegraph signalling let busier, faster railways run safely.
When and how
Paddington to West Drayton, west London, 1838–39; telegraph-based 'block' signalling spread from the 1840s.
How we know
Railway company records, and the 1845 arrest of murderer John Tawell, caught after a telegraph message outran his train to London.
Debates and open questions
Whether railways would have grown so fast without the telegraph, or the telegraph without railway rights-of-way, is a chicken-and-egg question.
▸Electric telegraph spanned the ocean with the Transatlantic telegraph cableWell documented
The connection
Land telegraphs already linked cities in minutes, but news between Europe and America still took about ten days by ship. An ocean cable needed gutta-percha, a tree latex, for insulation, plus William Thomson's theory of signal delay and his sensitive mirror galvanometer to read faint, smeared pulses.
When and how
Cyrus Field's Atlantic Telegraph Company, 1856; William Thomson, later Lord Kelvin, in Glasgow; the first lasting undersea cable crossed the English Channel in 1851.
How we know
Thomson's published papers on signal delay, company records, and the 1858 exchange between Queen Victoria and President Buchanan.
Debates and open questions
Whether the 1858 cable failed mainly because electrician Wildman Whitehouse applied excessive voltage, or from poor manufacture and storage, is still argued.
▸Electric telegraph led to the TelephoneWell documented
The connection
The telegraph was the big market, and inventors including Bell and Gray were trying to send several messages at once on one wire using different tones, a 'harmonic telegraph'. Working on that, Bell realized a wire could carry the full shape of a voice. Early phone networks reused telegraph-style wires, poles and switchboards.
When and how
Boston, 1874–76, Bell with assistant Thomas Watson; Chicago, Elisha Gray, co-founder of the telegraph-equipment maker Western Electric.
How we know
Bell's notebooks and patent grew out of his harmonic telegraph work; telegraph giant Western Union entered the phone business with Gray's and Edison's designs, then settled with Bell in 1879.
Debates and open questions
The story that Western Union turned down Bell's patent for $100,000 is often retold, but the evidence for it is thin.
▸Electric telegraph went wireless as RadioWell documented
The connection
Radio began as 'wireless telegraphy': Marconi sent Morse code dots and dashes without wires, aiming at places the telegraph could not reach, above all ships at sea. Operators used telegraph skills and codes. Voice and music came later, once vacuum tubes made them possible.
When and how
Marconi's experiments near Bologna, Italy, in 1895; his company in Britain from 1897; ship-to-shore stations spread worldwide in the 1900s.
How we know
Marconi's 1896 patent covered 'transmitting electrical impulses and signals', and his company's early business was ship and transatlantic telegrams.
Debates and open questions
Whether radio grew mainly out of telegraphy or out of physicists' work on Hertz's waves is a matter of emphasis; both strands mattered.
▸Electric telegraph foreshadowed The Internet (TCP/IP)Mostly agreed
The connection
The telegraph was the first network to send messages as electrical signals, faster than any messenger, and it introduced ideas the Internet reuses: coded messages, addresses, and relay offices that stored each message and forwarded it toward its destination. Writer Tom Standage called it 'the Victorian Internet.'
When and how
Telegraph: Britain and the US, 1837–1844. Internet: Cerf and Kahn's 1974 design, building on 1960s packet switching, itself a faster form of telegraph-style 'store and forward' message switching.
How sure are we?
1960s papers by packet-switching pioneers present their designs as improvements on message switching, the method telegraph networks used; the rest of the link is analogy.
Debates and open questions
'Foreshadowed' is a judgment call: some see the telegraph as a true ancestor, others as a loose analogy, since packets and routers were genuinely new inventions.
▸Volta's electric battery powered the Electric telegraphWell documented
The connection
Early telegraphs needed steady current to push signals through miles of wire. Improved batteries descended from Volta's pile, such as Daniell's cell (1836), supplied it. Telegraph offices kept rooms of jars filled with zinc, copper and acid; generators replaced them on big lines only late in the century.
When and how
Britain and the US, 1837–1870s; John Frederic Daniell's cell, London, 1836; William Grove's cell, 1839, used on early Morse lines.
How we know
Telegraph manuals and company records describe the battery rooms, the cell types and their upkeep in detail.
Debates and open questions
How much battery cost and upkeep, rather than wire and labor, limited the telegraph's early growth has not been well measured.
▸The alphabet was encoded as dots and dashes by the Electric telegraphWell documented
The connection
Because an alphabet breaks language into a few dozen letters, it is easy to code. Morse code gave each letter a pattern of short and long electric pulses, so any message could travel over a single wire. Languages with thousands of characters, like Chinese, needed codebooks that turned each character into a number.
When and how
United States, 1838 to 1844: Samuel Morse and Alfred Vail developed the code; the first US intercity line ran from Washington to Baltimore in 1844.
How we know
Morse and Vail's code tables survive, and the 1844 message 'What hath God wrought' is well documented.
Debates and open questions
How much of the letter code was Vail's work rather than Morse's is disputed.