150 years ago, nine words changed the world

On March 10, 1876, a 29-year-old Scottish immigrant named Alexander Graham Bell sat in a modest laboratory at 5 Exeter Place in Boston and did something no human being had ever done: He spoke into a wire, and someone in the next room heard his voice. His exact words, recorded in his laboratory notebook: “Mr. Watson — Come here — I want to see you.” His assistant, a 22-year-old mechanic named Thomas Watson, came running.

That was it. Nine words, shouted through a crude device that used...