Dec. 12: Inventor Guglielmo Marconi amazes a London assemblage in 1896 with a demonstration of wireless communication across a room. Five years later to the date, Marconi sends the first signal across an ocean.

Marconi was the son of an Italian country gentleman and Irish whiskey heiress Anne Jameson. He took an early interest in physics, especially electricity. His neighbor in Bologna, physics professor Augusto Righi, encouraged Marconi to study the work of Heinrich Hertz.

In the attic of his villa, Marconi replicated Hertz’s experiments on “Hertzian waves,” detecting sparks in one circuit with another circuit a few meters away. By 1895 the young man extended the range to 2 kilometers.

Marconi tried to interest the Italian Ministry of Posts and Telegraphs in transmitting messages without wires, but the burocrati weren’t buying. In England, however, a maternal cousin introduced Marconi to William Henry Preece, engineer-in-chief of the British post office.

Preece had studied as a graduate student under Michael Faraday and was working with his own wireless devices as early as 1892. He arranged for a demonstration of Marconi’s advanced apparatus at Toynbee Hall, a center of social reform in East London.

The post-office engineer advertised the event and invited the press. Press is the operative word, because there were obviously no electronic media yet.

Marconi tapped a telegraph key in one part of the room, and Preece walked around with a receiver box. Every time Marconi hit the key, a bell rang. Look, Ma: no wires!

Tickle me, Guglielmo. The crowd was impressed. Marconi was 22 years old.

Marconi received the world’s first patent for a system of wireless telegraphy. He founded what would become the Marconi Wireless Telegraph Company in 1897 and opened the world’s first radio factory at Chelmsford, England, in 1898.

The young inventor kept working on improvements. He sent radio signals a distance of 12 miles in 1897 and across the English Channel (21 miles) in 1899. The following year, he received the famous patent No. 7777 for “tuned or syntonic telegraphy.” The concept was fundamental: Use different frequencies to allow simultaneous transmissions without interfering with one another. The improved signal quality also increased the range of radio transmission.

Still, there was the issue of the curvature of the Earth. Many people believed that would limit radio to local use. Marconi set out to prove them wrong.

And that he did. Assistants telegraphed a prearranged signal, the letter S (three clicks in Morse Code), from Poldhu in Cornwall, southwestern England, to Marconi at Signal Hill, St. John’s, Newfoundland, at 4:30 a.m. GMT on Dec. 12, 1901. (An attempt the previous night had failed when a windstorm knocked down the antenna, which was held aloft by a balloon.)

By sending a signal more than 2,100 miles across the Atlantic, Marconi convincingly demonstrated the practicality of worldwide wireless communication. And in 1909, he shared the Nobel Prize for physics with Karl Ferdinand Braun of Germany, whose modifications to Marconi’s transmitters made them strong enough to be practical.

Marconi predicted the advent of radar in a lecture to the American Institute of Radio Engineers in 1922. His own research progressed from short-wave radio to microwaves, and in 1932 he opened the world’s first microwave radiotelephone link. It connected Vatican City with the pope’s summer palace at Castel Gandolfo.

Marconi actively supported and then served in Benito Mussolini’s Fascist government of Italy. Mussolini rewarded him in 1929 with the noble title of marchese, and when Marconi died in 1937, Mussolini gave him a state funeral.

Photo: Inventor Guglielmo Marconi took wireless telegraphy from across-the-room demo to across-the-ocean success in just five years. Courtesy: Pack Brothers

This article first appeared on Wired.com Dec. 12, 2008.