Remus Carey uses Morse Code to communicate at various points in his career. Although it is falling out of use due to various technological advances and other means of reliable communication, there is one particular episode within the Sarnian series where he has to fall back on this most universal of languages, as his only means of sending a message.
Morse Code alphabet
Each character is built up using a series of dots and dashes with the most often used in English represented by some of the simplest combinations, such as a single dot for E, a single dash for T and, most famous of all, three dots for S and three dots for O (so the emergency code SOS — Save Our Souls — is
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Although it my look seem entirely illogical translating the alphabet into such a confusing combination of symbols, it was originally developed for use on the telegraph where it was only possible to send an electrical current over a wire, turning it on and off every time the operator completed a circuit at the sending station.
In the original implementation, developed by Samuel Morse and others, when the circuit was complete it would make indentations in a piece of paper at the receiving station, which would indicate to the operator which number the sender was spelling out, and enable them to look up the corresponding message in a code book.
Alfred Vail went on to expand the system to include all of the letters in the English alphabet, and the system was later upgraded to swap out the paper for a buzzer.
So, when the circuit was complete it would cause a buzzer to sound at the receiving station. By varying the length of time that the circuit was complete it was possible to control how long the buzzer sounded for, and thus use the code above to spell out individual letters. Likewise, by using the same combinations with a flashing light, it was possible to communicate silently — particularly over the sea.