SOS is a Morse code distress signal (· · · — — — · · ·) that is internationally recognised as a request for help. Contrary to what some people may believe, SOS does not stand for “Save our Ship” or “Save Our Souls”. The letters "SOS" don’t, in fact, stand for anything. They just happen to be the letters that correspond to the Morse code signal comprised of three dots, three dashes, and then three more dots.

Morse Code was developed by Samuel Morse in 1835. Using a series of dots and dashes to represent the letters of the alphabet, telegraphers could communicate messages by sending pulses of electric current through telegraph wires. Dots are an electrical pulse of one unit of measurement. Dashes are represented by an electrical pulse of three units of measurement.

Each letter of the alphabet, along with Arabic numerals and some punctuation, was assigned a unique combination of dots and dashes to represent it. The letter “E” and the letter “T” are the shortest, with E being assigned a single dot and T a single dash. Two letters of the alphabet are a series of three, with O consisting of three dashes, and S consisting of three dots.

Germany was the first country to adopt the SOS distress signal, which it called the Notzeichen signal, as one of three Morse code sequences included in national radio regulations which became effective on 1 April 1905.In 1906, the first International Radiotelegraph Convention met in Berlin, which produced an agreement signed on 3 November 1906 that become effective on 1 July 1908. The convention adopted an extensive collection of Service Regulations, including Article XVI, which read: "Ships in distress shall use the following signal: · · · — — — · · · repeated at brief intervals".

Even though the SOS signal was internationally ratified in 1908, old habits die hard. The British continued to use an alternative “CQD” signal (CQ ”sécu", from the French word sécurité, followed by D for “Distress”) that was established by the Marconi International Marine Communication Company in 1904; and indeed on 15 April 1912, a full 4 years after the adoption of the new international standard, the RMS Titanic initially used CQD as their distress call six times before beginning to intersperse it with SOS.

The Cunard liner RMS Slavonia, on the day it was wrecked on 10 June 1909, is the earliest-reported ship to have transmitted the SOS distress call.

With the development of audio radio transmitters, there was a need for a spoken distress phrase, and "Mayday" (from French m'aider "help me") was adopted by the 1927 International Radio Convention as the spoken equivalent of SOS.

SOS has expanded beyond the audible. Due to its simplicity, SOS can be communicated by flashlight with three short bursts of light, followed by three longer bursts, followed again by three shorter bursts of light.

Finally, SOS has been used on numerous occasions to communicate distress in the sand. In 2012, 5 stranded snorkelers were rescued off the northeastern coast of Australia after creating an SOS message on a sandbar.

The best thing about the SOS signal is that no matter where you live, or what language you speak, everybody now understands SOS signals. Just keep in mind that the letters aren’t actually short for anything.

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References

https://en.wikipedia.org/wiki/SOS
https://www.sporcle.com/blog/2017/10/what-does-sos-stand-for/
http://edition.cnn.com/2014/04/24/world/australia-sos-ocean-rescue/

Images

1. SOS
2. Morse Code Image © Jim Lambert | Dreamstime.com
3. Samuel F.B. Morse circa 1860. Brady-Handy Photograph Collection/Library of Congress, Washington, D.C.
4. The only known picture of Titanic's wireless radio room, taken by the Catholic priest Francis Browne.
5. Cunard liner RMS Slavonia on the day it was wrecked on 10 June 1909
6. Sandbar SOS. Image: RACQ CQ RESCUE/EPA