HUMANITIES & SOCIAL SCIENCES LIBRARY / NEW YORK PUBLIC LIBRARY / SCIENCE PHOTO LIBRARY HUMANITIES & SOCIAL SCIENCES LIBRARY / NEW YORK PUBLIC LIBRARY / SCIENCE PHOTO LIBRARY
Marconi radio valve. This is a Marconi transmitter valve of the type M.T.6. Marconi patented his radio equipment in 1896, founding a company in 1897 to build the new equipment. The thermionic valve, or vacuum tube, first developed in 1906, is a device used to amplify or modify a voltage, in this case to transmit a radio signal. Photograph courtesy of the Radio Corporation of America, New York, USA, formed in 1920 from the American Marconi Company. Photographed for The March of Commerce (1927), volume 4 of The Pageant of America: A Pictorial History of the United States, a 15-volume series that commemorated 150 years since the founding of the USA in 1776.
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