SOS is a really versatile distress call. You can shout it; you can tap it out in Morse code; you can honk it on a horn; you can signal it with flashes of light; you can spell it out on the beach with debris from your wrecked ship. Explaining where SOS came from and what it means are maritime archivist Christian Ostersehlte from the German Maritime Museum, and Paul Tyreman from PK Porthcurno, the Museum of Global Telecommunications. Find more information about the topics in this episode at theallusionist.org/sos.  There are a couple of category B swears in this episode. The music is by Martin Austwick. Hear Martin’s own songs at palebirdmusic.com or search for Pale Bird on Bandcamp and Spotify, and he’s @martinaustwick on Twitter and Instagram.  The Allusionist's online home is theallusionist.org. Support the show by becoming a patron at patreon.com/allusionist. Stay in touch at twitter.com/allusionistshow, facebook.com/allusionists how and instagram.com/allusionistshow. This episode is sponsored by: • Skillshare, the online learning community with thousands of inspiring classes for creative and curious people. Explore your creativity at Skillshare.com/allusionist and get a free trial of Premium Membership. • Bombas, makers of the most comfortable socks in the history of feet. Give a pair when you buy a pair, and get twenty percent off your first purchase at bombas.com/allusionist. • Squarespace, your one-stop shop for building and running a sleek website. Go to squarespace.com/allusionist for a free trial, and get 10 percent off your first purchase of a website or domain with the code allusionist. Support the show: http://patreon.com/allusionist See omnystudio.com/listener for privacy information.