Morse code most common letter in English, the letter "E", has the shortest code: a single dot. Because the Morse code elements are specified by proportion rather than specific time durations, the code is usually transmitted at the highest rate that the receiver is capable of decoding. The Morse code transmission rate ("speed") is specified in "groups per minute", commonly referred to as "words per minute". Morse code is usually transmitted by on-off keying of an information carrying medium such as electric current, radio waves, visible light or sound waves. The current or wave is present during time period of the dot
American Morse code which supplanted American Morse. American Morse Code was first used on the Baltimore-Washington telegraph line, a telegraph line constructed between Baltimore, Maryland, and the old Supreme Court chamber in the Capitol building in Washington, D.C. The first public message "What hath God wrought" was sent on May 24, 1844, by Morse in Washington to Alfred Vail at the Baltimore and Ohio Railroad (B&O) "outer depot" (now the B&O Railroad Museum) in Baltimore. The message is a Bible verse from Numbers 23:23, chosen for Morse by Annie Ellsworth, daughter of the Governor of Connecticut. The original paper tape received by Vail