Encyclopedia of Radio 3-Volume Set

E

EARLY WIRELESS

Induction and Conduction before 1900

Although Marconi, Lodge, Popov, and their contemporaries were the first electricians to make practical use of electromagnetic waves for communication, varied forms of wireless telegraphy had existed for 50 years before their work at the end of the 19th century. Most of the wireless inventors of this early era were Americans.

Henry and Morse

Joseph Henry, at Princeton University, conducted numerous experiments with induction, or the tendency of a primary electric current in a conductor to stimulate a secondary current in another conductor nearby. During one group of experiments in 1842, which Henry called “induction at a distance,” he measured secondary current as far as 200 feet away from ...