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 |