Morse Code.

Samuel F. B. Morse demonstrated a simple but stunning invention in 1837. It was a machine that could send a clicking signal across a wire. Using his code that related clicking patterns to letters of the alphabet, Morse could transmit messages wherever he could string his telegraph cable. The new technology was promising enough to encourage Congress to foot the bill for a test line between Baltimore and Washington in 1843, and within a year the experiment had proved successful. The challenge was to cover the country with telegraph cable.

Messages in Minutes.

Before the telegraph, the only way people could communicate with others in distant places was to send them letters or to travel to meet them. The telegraph allowed a person to transmit a message over hundreds and, eventually, thousands of miles in the space of perhaps an hour. By the 1850s...