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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, documents and manuscripts from late seventeenth and eighteenth century France, especially from the French Revolution, collected by Sam Schaefler. Authors include J.B. Colbert Torcy and the Duchesse Du Lude. Many of the items from the French Revolution represent the work of the Committee of Public Safety and the Committee of General Security. French Revolutionary leaders represented in the collection include François-Antoine Boissy D'Anglas, Jean-Baptiste-Noel Bouchotte, Pierre Joseph Cambon, Lazare Carnot, Jean-Marie Collot D'Herbois, l'Abbʹe de Fauchet, Philippe-Antoine Merlin de Douai, Jean Victor Moreau. C.A. Prieur-Duvernois, and Antoine Joseph Santerre. In addition, the collection includes a letter from the Danish physicist Hans Christian Oersted to Sir John Herschel, a letter by the French poet Romain Rolland, a document of the Philadelphia Artists' Fund Society of 1846 with signatures of its officers, and an autograph letter and a photograph of Henry Wadsworth Longfellow.