High-speed digital communication
The telegraph required a new way of writing messages.
For reasons none of us can identify, our navigator was recalling this week that a requirement for his original merchant marine license was to learn the Morse code. In this, each letter of the alphabet (plus each of several auxiliary items) is matched with a specific sequence of long and short tones, or clicks, or flashes of a light. Boy Scouts used to learn it also (we don’t know if they still do), as well as professional and amateur radio operators. It has now been superseded by other codes almost everywhere, and has something of the status of the slide rule.
But consider the situation in the mid-nineteenth century, when the electric telegraph started to become a practical proposition. One could transmit an electric signal for long distances over a wire, but almost all that was received was a “signal on” or “signal off.” There was no question of sending a written message, like a letter; or a spoken one, as by a human messenger. A new way of representing information had to be developed. Various methods were invented to output actual letters, but they depended on complicated mechanisms and often on stringing several wires together between stations. If you’re going to string miles of wire, you want to keep the stringing simple. What finally emerged was a digital encoding of text.
[We point out that it is not a binary encoding, as digital computers have used since their beginning. It could be thought of as a ternary system, with the three values “dot,” “dash” and “off,” the only example of such a system that we know of ever in practical use.]
Morse was still a very important system even after the invention of analog encoding of sound for transmission over wires (the telephone). In modern terms, it requires a very small bandwidth, low power and is robust against interference. It easily migrated to radio (wireless telegraphy) and maintained itself there for the same reasons. A series of dots and dashes will get through even when the ionosphere makes hash of any spoken message.
[One of our consultants remembers a science fiction story from the middle of the 20th century in which a spaceship on its way to, he thinks, Jupiter encounters serious interference, such that a spoken message was unintelligible; but one of the crew sings a Morse message over the voice radio, and is understood. It is characteristic of the genre of the time to mix an essentially 1940s communication technology with a propulsion technology not evident even in the 2020s.]
What interests us, however, is something that we’ve not seen pointed out before. There had been previous encodings of messages for transmission over distance. Naval ships had been using sequences of flags to convey orders and reports within fleets, and there were accepted meanings of signals even among merchant ships. But these were governed by code books and limited to what could be foreseen in advance. When Admiral Nelson at Trafalgar wanted to say something not covered by his book, he had to spell it out letter by letter, clumsily. Morse code was the first generally applicable, generally used way of transforming any text for transmission by high-speed digital means. It must have meant a profound change in the way some people processed information. We would be very interested in a psychological study of nineteenth-century Morse operators.
