The May 2024 issue of IEEE Spectrum is here!

Close bar

Book: The History of Radio, in Pictures and Words

A coffee-table book from the American Museum of Radio and Electricity chronicles five centuries of progress

0 min read

MORSE’S MAGNET: In the 1800s, electromagnetism became increasingly important, as in the telegraph, where closing and opening a circuit remotely activated an electromagnet. In this 1837 Samuel Morse demonstration telegraph, a “port-rule” transmitter [foreground] transmits the numbers 1 through 9 to the pen register receiver [rear]. A codebook translated numbers into messages. For example, “8732” might mean “reply requested.”
The Conversation (0)