An international code for relaying messages by wire or radio is called Morse Code. These signals are called dots and dashes. The dots are the short signals and the dashes are the long ones. The code was invented by Samuel Morse to use on his telegraph. The international signal used when someone was in trouble was SOS. These letters stood for three short signals, three long signals, three short signals. It is still used today; however, now by radio telephone, the distress call is "Mayday."

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