General knowledge · Culture & customs

Morse code

1844; international version standardised 1865

Communication — dots and dashes over the telegraph wire

A method of encoding text as two signal lengths, dots (dits) and dashes (dahs), named after the American artist and inventor Samuel Morse, though the alphabetic code itself was largely the work of his engineer Alfred Vail. Vail set the shortest signals against the commonest letters — E is a single dot, T a single dash — after counting type in a New Jersey print shop. Friedrich Gerke's German revision became the basis of International Morse, standardised in Paris in 1865, and the code served as the world's maritime distress language until 1999.

How to spot them

▸Dots and dashes, dits and dahs; E is one dot and T one dash
▸'What hath God wrought', the first message sent over an American telegraph line
▸Three dots, three dashes, three dots — the distress signal that stands for no words at all
▸Dropped as the maritime distress standard in 1999 for GMDSS

Key facts

'What hath God wrought', sent from Washington to Baltimore on 24 May 1844 (1844)

The words were chosen from Numbers 23:23 by Annie Ellsworth, daughter of the Patent Commissioner

Alfred Vail counted printers' type in a New Jersey newspaper office to decide the signal lengths (1840)

So the commonest English letters got the shortest signals: E a single dit, T a single dah

· · · — — — · · · , a distress prosign that is not an abbreviation for anything

'Save Our Souls' is a later backronym; it was chosen simply for being unmistakable

Friedrich Gerke's 1848 German revision, standardised internationally at Paris in 1865 (1865)

Only E, H, K and N survived unchanged from the original American version

Jeremiah Denton blinked T-O-R-T-U-R-E at the camera on North Vietnamese television in 1966 (1966)

A prisoner of war signalling what was being done to him

Retired as the maritime distress standard in 1999, in favour of a satellite system (1999)

The last US commercial transmission signed off with the 1844 message and the prosign SK

The opening of Beethoven's Fifth matches the letter V, which the BBC used for 'Victory'

Three short and one long

Key ideas

Element lengths are relative, not absolute: a dash is three dits long, the gap between elements one dit, between letters three and between words seven. So the code can be sent at whatever speed the receiver can follow.

Quick-fire facts

•Samuel Morse was a professional portrait painter before he turned to telegraphy
•The alphabetic code was largely devised by Alfred Vail in 1840; Morse's own first plan sent only numbers, to be looked up in a codebook
•The famous first public message, 'What hath God wrought', was sent from the US Capitol to Baltimore on 24 May 1844
•The original American (or 'railroad') version differs from International Morse, which grew from Friedrich Gerke's 1848 revision
•International Morse was standardised at the Paris conference of 17 May 1865 that created the International Telegraph Union
•SOS was introduced in German regulations in 1905 and agreed internationally at Berlin in 1906; it is a single prosign, not an abbreviation
•The previous distress call was CQD, sometimes glossed as 'come quick, danger'; the Titanic sent both in 1912
•Morse code ceased to be the maritime distress standard on 1 February 1999, replaced by the Global Maritime Distress and Safety System
•Proficiency was required for amateur radio licences worldwide until the World Radiocommunication Conference of 2003 made it optional
•The French Navy's last Morse transmission, in January 1997, ended: 'Calling all. This is our last call before our eternal silence'

Drill it — 9 cards

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Sources

Tom Standage — The Victorian Internet
Library of Congress — Samuel F. B. Morse Papers at the Library of Congress Digitised papers and essays on the invention of the telegraph; cited without URL