On This Day: Marconi Receives First Trans-Atlantic Radio Signal

Last updated: February 15, 2023

On Dec. 12, 1901, at a site set up in St. John’s, Newfoundland, Guglielmo Marconi revolutionized international communications when he heard three little clicks—the “S” in Morse code—sent by his colleagues from a transmitter in Cornwall, England.

Marconi’s Breakthrough

As a student at the University of Bologna, Guglielmo Marconi studied the theories of Heinrich Hertz, a pioneer in wireless radio transmission. In 1896, soon after graduation, Marconi moved with his Irish-born mother to England, where he set up his first company with an English cousin.

Marconi experimented with sending signals in England, and to France and Ireland. He gained international fame in 1899, when he transmitted the results of the America’s Cup sailing race to a New York newspaper from the deck of a ship.

In 1901, he began working on a way to transmit radio signals across the Atlantic Ocean. He built powerful stations in Poldhu, Cornwall, England and South Wellfleet, Cape Cod, Mass. He later moved his North American station to Signal Hill, St. John’s, Newfoundland, located much closer to England, when he estimated that the signals could not reach Cape Cod.

Many scientists believed that radio signals could not be transmitted such a long distance. The prevailing theory was that a signal could not travel along the curvatures of the Earth for more than a few hundred miles; instead, the signal would continue into space.

At Signal Hill, Marconi and his assistant George Kemp held a telephone receiver and a wire antenna in the air with a kite. On Dec. 10, the Poldhu sent a message, but Marconi could not receive it. Two days later, using the fourth kite of the experiment, Marconi and Kemp at last heard a signal.

“The answer came at 12:30 when I heard, faintly but distinctly, pip-pip-pip,” Marconi later wrote. “I handed the phone to Kemp: ‘Can you hear anything?’ I asked. ‘Yes,’ he said. ‘The letter S.’ He could hear it. I knew then that all my anticipations had been justified. The electric waves sent out into space from Poldhu had traversed the Atlantic—the distance, enormous as it seemed then, of 1,700 miles—unimpeded by the curvature of the earth.”

The New York Times called Marconi’s transatlantic experiment in 1901, “the most wonderful scientific development of recent times.”

How the Experiment Succeeded

Related Events

Though Marconi’s experiment had succeeded, he was wrong to believe that the signal had traveled along the curvature of the Earth. Instead, as his critics believed, the signal was headed into space until it struck an atmospheric layer of ions that deflected back down toward St. John’s.

In studying Marconi’s success, American engineer Arthur Kennelly and British physicist Oliver Heaviside independently theorized the existence of the ionosphere, which became known as the Kennelly-Heaviside layer.

Lawsuits and Patent Disputes

Sources in this Story

  • PBS: Guglielmo Marconi
  • IEEE: History Center: Reception of Transatlantic Radio Signals, 1901
  • PBS: Marconi receives radio signal over Atlantic, 1901
  • BNET (Social Research): Marconi's error: the first transatlantic wireless telegraphy in 1901
  • The New York Times: Wireless signals across the ocean
  • Newfoundland and Labrador Heritage: Marconi
  • University of Oxford: Museum of History of Science: Wireless World: Marconi & the making of radio
  • Encyclopedia Britannica: Guglielmo Marconi
  • PBS: Who Invented Radio?
  • The Nobel Foundation: Nobel Prize for Physics 1909

Marconi’s experiment sparked numerous patent battles and other legal disputes. The Anglo-American Telegraph Company, which held a monopoly on telegraph transmissions in Newfoundland, threatened to sue if Marconi continued to receive telegraph transmissions, so Marconi, at Canada’s invitation, moved to a new site on Cape Breton Island.

Marconi had more prolonged difficulty over the patent that made his success possible. In 1900, he received a patent, No. 7777, from the British government for “tuned or syntonic telegraphy,” which allowed for transmissions at different frequencies; thus, signals could be sent on different wavelengths and not interfere with each other.

The patent, which became known as “four sevens” even in countries where the patent number was different, was based closely on the patented work of Oliver Lodge, Nikola Tesla and John Stone. The U.S. Patent Office repeatedly rejected Marconi’s application until 1904, when the “powerful financial backing for Marconi,” may have influenced the Patent Office, according to PBS.

Tesla sued Marconi in 1915, one of many lawsuits brought over the “four sevens” patent. It wasn’t until 1943, after Marconi and Tesla’s deaths, that the U.S. Supreme Court ruled in favor of Tesla. The decision was due in large part to a lawsuit brought by the Marconi Company against the U.S. government.

Key Player: Guglielmo Marconi

Marconi continued working on wireless telegraphy and radio technology for the remainder of his life. He served in the Italian military during World War I, working to improve its wireless communication. In the 1920s, he conducted experiments from a yacht, the Elettra, that he sailed through the Atlantic and Mediterranean.

He received many honors during his life, including the 1909 Nobel Prize for Physics. He was particularly celebrated in his native Italy, where he was made a marchese, named to the senate and appointed president of the Academy of Italy. Marconi was a member of the Fascist Party and enjoyed a close relationship with Prime Minister Benito Mussolini; in 2002, historians uncovered evidence that he kept Jews out of the Academy at Mussolini’s behest.

Marconi died of a heart attack on July 20, 1937. Watch newsreel footage of his funeral procession through Rome with Mussolini in attendance.

The University of Oxford and its Museum of History of Science hosts the Marconi Collection, featuring an archive of objects and documents belonging to Marconi and his telegraph companies.

Leave a Reply

Your email address will not be published. Required fields are marked *

linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram