Episode Details

On July 12, 1999, the United States sent its last commercial Morse message, repeating the 1844 words What hath God wrought, and in January 1997 the French Navy signed off with a call before its eternal silence. Yet the code never went quiet. Samuel Morse first planned to send only numbers keyed to heavy code books, but Alfred Vail counted the metal type in a Morristown, New Jersey print shop and gave the shortest codes to the most common letters, a variable length scheme that worked like data compression a century before computers. Operators soon ignored the paper tape and read the clicks by ear.

Vail's American Morse had odd gaps inside letters, so in 1848 Friedrich Clemens Gerke's Hamburg alphabet cleaned it up and became the basis of the 1865 international standard, though American railroad telegraphers kept the old code into the 1950s. Timing runs in ratios of one, three, and seven dits. Each operator's timing quirks form a fist that Allied intelligence used in World War II to track units. The code lives on in aviation beacons, amateur radio, and assistive switches such as sip and puff tubes.

• Theodore Roosevelt McElroy set the copying record of 75.2 words per minute in 1939.
• At high speed operators hear whole words as melodic shapes rather than single dots and dashes.
• A Morse signal fits in roughly 100 to 150 hertz, letting it punch through static that swamps voice.
• In 1966 prisoner of war Jeremiah Denton blinked the word torture in Morse during a North Vietnamese propaganda broadcast.
• In 2004 the International Telecommunication Union added the @ symbol so email addresses could be sent.