The encyclopedia · Software & IT · Technical decision · 1837-1844
Morse code won the wire by giving frequent letters the shortest signals.
Alfred Vail gave the shortest dot-dash codes to the most common English letters, so Morse's telegraph sent messages fast and cheap and became the world's code.
Samuel Morse · Alfred Vail
the move
Samuel Morse's telegraph needed a way to turn letters into electrical pulses. Alfred Vail improved the original idea and settled on short and long marks, dots and dashes, to spell each letter.
To make the code efficient, Vail tried to measure how often each letter appears in English. He found the answer in the type-cases of a local newspaper's compositors, then assigned the shortest sequences to the most frequent letters, so an E was one dot and a rare letter a long group.
Because it cut the strokes needed per message, the code was cheaper and faster on the wire. In 1844 Morse sent the famous 'What hath God wrought' test message, and the system spread as the standard telegraph alphabet.
why it works
- Shortest codes for E and T save strokes on almost every message
- Frequency came from typesetting evidence, not guesswork
- Fewer strokes meant faster, cheaper messages on a costly line
- It was simple and it worked, so operators and armies adopted it
what transfers
When a channel is expensive, code for the things you say most; frequency-weighted encoding buys speed for free, and it becomes the standard.
what came after
The code became the universal telegraph alphabet, then international Morse via the 1851 Berlin conference, and stayed in use for radio, aircraft and ships long after the telegraph. It is a textbook case of coding a channel for the frequencies of its traffic.
references
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