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Professional and personal files including Armstrong's correspondence with professional associations, other engineers, and friends, his research notes, circuit diagrams, lectures, articles, legal papers, and other related materials. Of his many inventions and developments, the most important are: 1) the regenerative or feedback circuit, 1912, the first amplified radio reception, 2) the superheterodyne circuit, 1918, the basis of modern radio and radar, 3) superregeneration, 1922, a very simple, high-power receiver now used in emergency mobile service, and 4) frequency modulation - FM, 1933, static-free radio reception of high fidelity. More than half the files concern his many lawsuits, primarily with Radio Corporation of America, over infringement of the Armstrong patents. Litigation continued until 1967. Other files deal with his work in the Marcellus Hartley Research Laboratory at Columbia University, 1913-1935, and with the American Expeditionary Forces in France during World War I, his Air Force contracts for communications development, Army research during World War II, the Radio Club of America, the Institute of Radio Engineers, FM development at his radio station at Alpine, N.J., the use of FM in television, his involvement in Federal Communications Commission hearings and legislation, and his work with the Zenith Radio Corporation. Also, letters to H.J. Round

Correspondence, manuscripts, documents, notebooks, memorabilia, a tape cassette, photographs, and printed materials. The collection is primarily correspondence files, both personal and professional, along with book reviews, awards and diplomas, letters of condolence on his death, clippings, and correspondence, manuscripts and printed materials relating to THE STREAM OF HISTORY. The correspondence relates specifically to the third edition. The manuscripts are typed and holograph inserts for the third edition and possibly for the second edition as well. Among the manuscripts are twenty-two notebooks containing holograph notes and drafts of chapters. The printed material consists of one copy of THE STREAM OF HISTORY, 1934 edition.