What is the Morse code?

In 1835, the American painter-turned-scientist Samuel F.B. Morse devised a code composed of dots and dashes to represent letters, numbers, and punctuation. Telegraphy—the long-distance transmission of a message—uses an electromagnet, a device that becomes magnetic when activated and raps against a metal contact. A series of short electrical impulses repeatedly can make and break this magnetism, resulting in a tapped-out message. Morse secured his patent on the code in 1837, and several years later established a communications company with machinist and inventor Alfred Vail. In 1844, the first long-distance telegraphed message was sent by Morse in Washington, D.C., to Vail in Baltimore, Maryland. This was the same year that Morse took out a patent on the telegraphy, although he did not acknowledge the unpatented contributions of Joseph Henry, who invented the first electric motor and working electromagnet in 1829 and the electric telegraph in 1831. Still in use today by the military, the maritime service, and by amateur radio operators, the International Morse Code now uses sound or a flashing light to send messages.

Morse code messages used to be transmitted to and from telegraph offices like this one. In larger cities, big telegraph exchange rooms were filled with telegraph machines manned by large staffs.